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@ -3,7 +3,7 @@
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这是我们的 LAMP 系列教程的开始：如何在 Ubuntu 上安装 Apache web 服务器。
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这些说明适用于任何基于 Ubuntu 的发行版，包括 Ubuntu 14.04, Ubuntu 16.04, [Ubuntu 18.04][1]，甚至非 LTS 的 Ubuntu 发行版，例如 Ubuntu 17.10。这些说明经过测试并为 Ubuntu 16.04 编写。
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这些说明适用于任何基于 Ubuntu 的发行版，包括 Ubuntu 14.04、 Ubuntu 16.04、 [Ubuntu 18.04][1]，甚至非 LTS 的 Ubuntu 发行版，例如 Ubuntu 17.10。这些说明经过测试并为 Ubuntu 16.04 编写。
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Apache (又名 httpd) 是最受欢迎和使用最广泛的 web 服务器，所以这应该对每个人都有用。
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@ -11,9 +11,9 @@ Apache (又名 httpd) 是最受欢迎和使用最广泛的 web 服务器，所
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在我们开始之前，这里有一些要求和说明：
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* Apache 可能已经在你的服务器上安装了，所以开始之前首先检查一下。你可以使用 "apachectl -V" 命令来显示你正在使用的 Apache 的版本和一些其他信息。
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* 你需要一个 Ubuntu 服务器。你可以从 [Vultr][2] 购买一个，它们是[最便宜的云托管服务商][3]之一。它们的服务器价格每月 2.5 美元起。
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* 你需要有 root 用户或具有 sudo 访问权限的用户。下面的所有命令都由 root 用户自行，所以我们不必为每个命令都添加 'sudo'。
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* Apache 可能已经在你的服务器上安装了，所以开始之前首先检查一下。你可以使用 `apachectl -V` 命令来显示你正在使用的 Apache 的版本和一些其他信息。
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* 你需要一个 Ubuntu 服务器。你可以从 [Vultr][2] 购买一个，它们是[最便宜的云托管服务商][3]之一。它们的服务器价格每月 2.5 美元起。（LCTT 译注：广告 ≤_≤ ）
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* 你需要有 root 用户或具有 sudo 访问权限的用户。下面的所有命令都由 root 用户执行，所以我们不必为每个命令都添加 `sudo`。
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* 如果你使用 Ubuntu，则需要[启用 SSH][4]，如果你使用 Windows，则应该使用类似 [MobaXterm][5] 的 SSH 客户端。
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这就是全部要求和注释了，让我们进入安装过程。
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@ -21,16 +21,19 @@ Apache (又名 httpd) 是最受欢迎和使用最广泛的 web 服务器，所
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### 在 Ubuntu 上安装 Apache
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你需要做的第一件事就是更新 Ubuntu，这是在你做任何事情之前都应该做的。你可以运行：
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```
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apt-get update && apt-get upgrade
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```
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接下来，安装 Apache，运行以下命令：
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```
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apt-get install apache2
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```
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如果你愿意，你也可以安装 Apache 文档和一些 Apache 实用程序。对于我们稍后将要安装的一些模块，你将需要一些 Apache 实用程序。
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```
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apt-get install apache2-doc apache2-utils
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```
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@ -46,6 +49,7 @@ apt-get install apache2-doc apache2-utils
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#### 检查 Apache 是否正在运行
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默认情况下，Apache 设置为在机器启动时自动启动，因此你不必手动启用它。你可以使用以下命令检查它是否正在运行以及其他相关信息：
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```
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systemctl status apache2
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```
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@ -53,6 +57,7 @@ systemctl status apache2
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[![check if apache is running][6]][6]
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并且你可以检查你正在使用的版本：
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```
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apachectl -V
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```
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@ -64,6 +69,7 @@ apachectl -V
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如果你使用防火墙（你应该使用它），则可能需要更新防火墙规则并允许访问默认端口。Ubuntu 上最常用的防火墙是 UFW，因此以下说明使用于 UFW。
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要允许通过 80（http）和 443（https）端口的流量，运行以下命令：
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```
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ufw allow 'Apache Full'
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```
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@ -76,18 +82,21 @@ ufw allow 'Apache Full'
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PageSpeed 模块将自动优化并加速你的 Apache 服务器。
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首先，进入 [PageSpeed 下载页][7]并选择你需要的的文件。我们使用的是 64 位 Ubuntu 服务器，所以我们安装最新的稳定版本。使用 wget 下载它：
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首先，进入 [PageSpeed 下载页][7]并选择你需要的的文件。我们使用的是 64 位 Ubuntu 服务器，所以我们安装最新的稳定版本。使用 `wget` 下载它：
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```
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wget https://dl-ssl.google.com/dl/linux/direct/mod-pagespeed-stable_current_amd64.deb
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```
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然后，使用以下命令安装它：
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```
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dpkg -i mod-pagespeed-stable_current_amd64.deb
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apt-get -f install
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```
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重启 Apache 以使更改生效：
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```
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systemctl restart apache2
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```
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@ -95,6 +104,7 @@ systemctl restart apache2
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##### 使用 mod_rewrite 模块启动重写/重定向
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顾名思义，该模块用于重写（重定向）。如果你使用 WordPress 或任何其他 CMS 来处理此问题，你就需要它。要安装它，只需运行：
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```
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a2enmod rewrite
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```
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@ -104,11 +114,13 @@ a2enmod rewrite
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##### 使用 ModSecurity 模块保护你的 Apache
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顾名思义，ModSecurity 是一个用于安全性的模块，它基本上起着防火墙的作用，它可以监控你的流量。要安装它，运行以下命令：
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```
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apt-get install libapache2-modsecurity
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```
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再次重启 Apache：
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```
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systemctl restart apache2
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```
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@ -118,40 +130,46 @@ ModSecurity 自带了一个默认的设置，但如果你想扩展它，你可
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##### 使用 mod_evasive 模块抵御 DDoS 攻击
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尽管 mod_evasive 在防止攻击方面有多大用处值得商榷，但是你可以使用它来阻止和防止服务器上的 DDoS 攻击。要安装它，使用以下命令：
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```
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apt-get install libapache2-mod-evasive
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```
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默认情况下，mod_evasive 是禁用的，要启用它，编辑以下文件：
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```
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nano /etc/apache2/mods-enabled/evasive.conf
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```
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取消注释所有行（即删除 #），根据你的要求进行配置。如果你不知道要编辑什么，你可以保持原样。
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取消注释所有行（即删除 `#`），根据你的要求进行配置。如果你不知道要编辑什么，你可以保持原样。
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[![mod_evasive][9]][9]
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创建一个日志文件：
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```
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mkdir /var/log/mod_evasive
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chown -R www-data:www-data /var/log/mod_evasive
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```
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就是这样。现在重启 Apache 以使更改生效。
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```
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systemctl restart apache2
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```
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你可以安装和配置[附加模块][10]，但完全取决于你和你使用的软件。它们通常不是必需的。甚至我们上面包含的4个模块也不是必需的。如果特定应用需要模块，那么它们可能会注意到这一点。
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你可以安装和配置[附加模块][10]，但完全取决于你和你使用的软件。它们通常不是必需的。甚至我们上面包含的 4 个模块也不是必需的。如果特定应用需要模块，那么它们可能会注意到这一点。
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#### 用 Apache2Buddy 脚本优化 Apache
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Apache2Buddy 是一个可以自动调整 Apache 配置的脚本。你唯一需要做的就是运行下面的命令，脚本会自动完成剩下的工作：
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```
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curl -sL https://raw.githubusercontent.com/richardforth/apache2buddy/master/apache2buddy.pl | perl
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```
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如果你没有安装 curl，那么你可能需要安装它。使用以下命令来安装 curl：
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如果你没有安装 `curl`，那么你可能需要安装它。使用以下命令来安装 `curl`：
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```
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apt-get install curl
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```
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@ -165,15 +183,17 @@ apt-get install curl
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现在我们已经完成了所有的调优工作，让我们开始创建一个实际的网站。按照我们的指示创建一个简单的 HTML 页面和一个在 Apache 上运行的虚拟主机。
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你需要做的第一件事是为你的网站创建一个新的目录。运行以下命令来执行此操作：
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```
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mkdir -p /var/www/example.com/public_html
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```
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当然，将 example.com 替换为你所需的域名。你可以从 [Namecheap][11] 获得一个便宜的域名。
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当然，将 `example.com` 替换为你所需的域名。你可以从 [Namecheap][11] 获得一个便宜的域名。
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不要忘记在下面的所有命令中替换 example.com。
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不要忘记在下面的所有命令中替换 `example.com`。
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接下来，创建一个简单的静态网页。创建 HTML 文件：
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```
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nano /var/www/example.com/public_html/index.html
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```
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@ -193,17 +213,20 @@ nano /var/www/example.com/public_html/index.html
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保存并关闭文件。
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配置目录的权限：
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```
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chown -R www-data:www-data /var/www/example.com
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chmod -R og-r /var/www/example.com
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```
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为你的网站创建一个新的虚拟主机：
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```
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nano /etc/apache2/sites-available/example.com.conf
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```
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粘贴以下内容：
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```
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<VirtualHost *:80>
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ServerAdmin admin@example.com
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@ -217,32 +240,31 @@ nano /etc/apache2/sites-available/example.com.conf
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</VirtualHost>
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```
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这是一个基础的虚拟主机。根据你的设置，你可能需要更高级的 .conf 文件。
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这是一个基础的虚拟主机。根据你的设置，你可能需要更高级的 `.conf` 文件。
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在更新所有内容后保存并关闭文件。
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现在，使用以下命令启用虚拟主机：
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```
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a2ensite example.com.conf
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```
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最后，重启 Apache 以使更改生效：
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```
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systemctl restart apache2
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```
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这就是全部了，你做完了。现在你可以访问 example.com 并查看你的页面。
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--------------------------------------------------------------------------------
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via: https://thishosting.rocks/how-to-install-optimize-apache-ubuntu/
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作者：[ThisHosting][a]
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译者：[MjSeven](https://github.com/MjSeven)
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校对：[校对者ID](https://github.com/校对者ID)
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校对：[wxy](https://github.com/wxy)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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@ -3,15 +3,15 @@ Linux 局域网路由新手指南：第 2 部分
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上周 [我们学习了 IPv4 地址][1] 和如何使用管理员不可或缺的工具 —— ipcalc，今天我们继续学习更精彩的内容：局域网路由器。
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上周 [我们学习了 IPv4 地址][1] 和如何使用管理员不可或缺的工具 —— `ipcalc`，今天我们继续学习更精彩的内容：局域网路由器。
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VirtualBox 和 KVM 是测试路由的好工具，在本文中的所有示例都是在 KVM 中执行的。如果你喜欢使用物理硬件去做测试，那么你需要三台计算机：一台用作路由器，另外两台用于表示两个不同的网络。你也需要两台以太网交换机和相应的线缆。
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我们假设示例是一个有线以太局域网，为了更符合真实使用场景，我们将假设有一些桥接的无线接入点，当然我并不会使用这些无线接入点做任何事情。（我也不会去尝试所有的无线路由器，以及使用一个移动宽带设备连接到以太网的局域网口进行混合组网，因为它们需要进一步的安装和设置）
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我们假设这个示例是一个有线以太局域网，为了更符合真实使用场景，我们将假设有一些桥接的无线接入点，当然我并不会使用这些无线接入点做任何事情。（我也不会去尝试所有的无线路由器，以及使用一个移动宽带设备连接到以太网的局域网口进行混合组网，因为它们需要进一步的安装和设置）
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### 网段
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最简单的网段是两台计算机连接在同一个交换机上的相同地址空间中。这样两台计算机不需要路由器就可以相互通讯。这就是我们常说的术语 —— “广播域”，它表示所有在相同的网络中的一组主机。它们可能连接到一台单个的以太网交换机上，也可能是连接到多台交换机上。一个广播域可以包括通过以太网桥连接的两个不同的网络，通过网桥可以让两个网络像一个单个网络一样运转。无线访问点一般是桥接到有线以太网上。
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最简单的网段是两台计算机连接在同一个交换机上的相同地址空间中。这样两台计算机不需要路由器就可以相互通讯。这就是我们常说的术语 —— “广播域”，它表示所有在相同的网络中的一组主机。它们可能连接到一台单个的以太网交换机上，也可能是连接到多台交换机上。一个广播域可以包括通过以太网桥连接的两个不同的网络，通过网桥可以让两个网络像一个单个网络一样运转。无线访问点一般是桥接到有线以太网上。
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一个广播域仅当在它们通过一台网络路由器连接的情况下，才可以与不同的广播域进行通讯。
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@ -22,12 +22,13 @@ VirtualBox 和 KVM 是测试路由的好工具，在本文中的所有示例都
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一个广播域需要一台路由器才可以与其它广播域通讯。我们使用两台计算机和 `ip` 命令来解释这些。我们的两台计算机是 192.168.110.125 和 192.168.110.126，它们都插入到同一台以太网交换机上。在 VirtualBox 或 KVM 中，当你配置一个新网络的时候会自动创建一个虚拟交换机，因此，当你分配一个网络到虚拟虚拟机上时，就像是插入一个交换机一样。使用 `ip addr show` 去查看你的地址和网络接口名字。现在，这两台主机可以互 ping 成功。
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现在，给其中一台主机添加一个不同网络的地址：
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```
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# ip addr add 192.168.120.125/24 dev ens3
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```
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你可以指定一个网络接口名字，在示例中它的名字是 ens3。这不需要去添加一个网络前缀，在本案例中，它是 /24，但是显式地添加它并没有什么坏处。你可以使用 `ip` 命令去检查你的配置。下面的示例输出为了清晰其见进行了删减：
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你可以指定一个网络接口名字，在示例中它的名字是 `ens3`。这不需要去添加一个网络前缀，在本案例中，它是 `/24`，但是显式地添加它并没有什么坏处。你可以使用 `ip` 命令去检查你的配置。下面的示例输出为了清晰其见进行了删减：
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```
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$ ip addr show
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ens3:
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@ -35,7 +36,6 @@ ens3:
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valid_lft 875sec preferred_lft 875sec
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inet 192.168.120.125/24 scope global ens3
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valid_lft forever preferred_lft forever
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```
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主机在 192.168.120.125 上可以 ping 它自己（`ping 192.168.120.125`），这是对你的配置是否正确的一个基本校验，这个时候第二台计算机就已经不能 ping 通那个地址了。
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@ -45,30 +45,27 @@ ens3:
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* 第一个网络：192.168.110.0/24
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* 第二个网络：192.168.120.0/24
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接下来你的路由器必须配置去转发数据包。数据包转发默认是禁用的，你可以使用 `sysctl` 命令去检查它的配置：
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|
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```
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$ sysctl net.ipv4.ip_forward
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net.ipv4.ip_forward = 0
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||||
|
||||
```
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||||
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||||
0 意味着禁用，使用如下的命令去启用它：
|
||||
`0` 意味着禁用，使用如下的命令去启用它：
|
||||
|
||||
```
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# echo 1 > /proc/sys/net/ipv4/ip_forward
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||||
|
||||
```
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|
||||
接下来配置你的另一台主机做为第二个网络的一部分，你可以通过将原来在 192.168.110.0/24 的网络中的一台主机分配到 192.168.120.0/24 虚拟网络中，然后重新启动两个 “网络” 主机，注意不是路由器。（或者重启动网络；我年龄大了还有点懒，我记不住那些重启服务的奇怪命令，还不如重启网络来得干脆。）重启后各台机器的地址应该如下所示：
|
||||
|
||||
* 主机 1: 192.168.110.125
|
||||
* 主机 2: 192.168.120.135
|
||||
* 路由器: 192.168.110.126 and 192.168.120.136
|
||||
|
||||
接下来配置你的另一台主机做为第二个网络的一部分，你可以通过将原来在 192.168.110.0/24 的网络中的一台主机分配到 192.168.120.0/24 虚拟网络中，然后重新启动两个 “连网的” 主机，注意不是路由器。（或者重启动主机上的网络服务；我年龄大了还有点懒，我记不住那些重启服务的奇怪命令，还不如重启主机来得干脆。）重启后各台机器的地址应该如下所示：
|
||||
|
||||
* 主机 1： 192.168.110.125
|
||||
* 主机 2： 192.168.120.135
|
||||
* 路由器： 192.168.110.126 和 192.168.120.136
|
||||
|
||||
现在可以去随意 ping 它们，可以从任何一台计算机上 ping 到任何一台其它计算机上。使用虚拟机和各种 Linux 发行版做这些事时，可能会产生一些意想不到的问题，因此，有时候 ping 的通，有时候 ping 不通。不成功也是一件好事，这意味着你需要动手去创建一条静态路由。首先，查看已经存在的路由表。主机 1 和主机 2 的路由表如下所示：
|
||||
|
||||
```
|
||||
$ ip route show
|
||||
default via 192.168.110.1 dev ens3 proto static metric 100
|
||||
@ -82,26 +79,25 @@ default via 192.168.120.1 dev ens3 proto static metric 101
|
||||
src 192.168.110.126 metric 100
|
||||
192.168.120.0/24 dev ens9 proto kernel scope link
|
||||
src 192.168.120.136 metric 100
|
||||
|
||||
```
|
||||
|
||||
这显示了我们使用的由 KVM 分配的缺省路由。169.* 地址是自动链接的本地地址，我们不去管它。接下来我们看两条路由，这两条路由指向到我们的路由器。你可以有多条路由，在这个示例中我们将展示如何在主机 1 上添加一个非默认路由：
|
||||
|
||||
```
|
||||
# ip route add 192.168.120.0/24 via 192.168.110.126 dev ens3
|
||||
|
||||
```
|
||||
|
||||
这意味着主机1 可以通过路由器接口 192.168.110.126 去访问 192.168.110.0/24 网络。看一下它们是如何工作的？主机1 和路由器需要连接到相同的地址空间，然后路由器转发到其它的网络。
|
||||
这意味着主机 1 可以通过路由器接口 192.168.110.126 去访问 192.168.110.0/24 网络。看一下它们是如何工作的？主机 1 和路由器需要连接到相同的地址空间，然后路由器转发到其它的网络。
|
||||
|
||||
以下的命令去删除一条路由：
|
||||
|
||||
```
|
||||
# ip route del 192.168.120.0/24
|
||||
|
||||
```
|
||||
|
||||
在真实的案例中，你不需要像这样手动配置一台路由器，而是使用一个路由器守护程序，并通过 DHCP 做路由器通告，但是理解基本原理很重要。接下来我们将学习如何去配置一个易于使用的路由器守护程序来为你做这些事情。
|
||||
|
||||
通过来自 Linux 基金会和 edX 的免费课程 ["Linux 入门" ][2] 来学习更多 Linux 的知识。
|
||||
通过来自 Linux 基金会和 edX 的免费课程 [“Linux 入门”][2] 来学习更多 Linux 的知识。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
@ -109,10 +105,10 @@ via: https://www.linux.com/learn/intro-to-linux/2018/3/linux-lan-routing-beginne
|
||||
|
||||
作者：[CARLA SCHRODER][a]
|
||||
译者：[qhwdw](https://github.com/qhwdw)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://www.linux.com/users/cschroder
|
||||
[1]:https://www.linux.com/learn/intro-to-linux/2018/2/linux-lan-routing-beginners-part-1
|
||||
[1]:https://linux.cn/article-9657-1.html
|
||||
[2]:https://training.linuxfoundation.org/linux-courses/system-administration-training/introduction-to-linux
|
||||
@ -1,7 +1,10 @@
|
||||
使用树莓派构建一个婴儿监视器
|
||||
======
|
||||
|
||||
> 比一般的视频监控还要好，这种 DIY 型号还有婴儿房间的自动室温控制功能。
|
||||
|
||||
|
||||
|
||||
香港很湿热，即便是晚上，许多人为了更舒适，在家里也使用空调。当我的大儿子还是一个小婴儿的时候，他卧室的空调还是需要手动控制的，没有温度自动调节的功能。它的控制器只有开或者关，让空调整个晚上持续运行会导致房间过冷，并且也浪费能源和钱。
|
||||
|
||||
我决定使用一个基于 [树莓派][2] 的 [物联网][1] 解决方案去修复这个问题。后来我进一步为它添加了一个[婴儿监视器][3]插件。在这篇文章中，我将解释我是如何做的，它的代码在 [我的 GitHub][4] 页面上。
|
||||
@ -10,17 +13,17 @@
|
||||
|
||||
解决我的问题的第一个部分是使用了一个 Orvibo S20 [可通过 WiFi 连接的智能插头][5]和智能手机应用程序。虽然这样可以让我通过远程来控制空调，但是它还是手动处理的，而我希望尝试让它自动化。我在 [Instructables][6] 上找到了一个满足我的需求的项目：他使用树莓派从一个 [AM2302 传感器][7] 上测量附近的温度和湿度，并将它们记录到一个 MySQL 数据库中。
|
||||
|
||||
使用圧接头将温度/湿度传感器连接到树莓派的相应 GPIO 针脚上。幸运的是，AM2302 传感器有一个用于读取的 [开源软件][8]，并且同时提供了 [Python][9] 示例。
|
||||
使用压接头将温度/湿度传感器连接到树莓派的相应 GPIO 针脚上。幸运的是，AM2302 传感器有一个用于读取的 [开源软件][8]，并且同时提供了 [Python][9] 示例。
|
||||
|
||||
与我的项目放在一起的用于 [AM2302 传感器][10] 接口的软件已经更新了，并且我使用的原始代码现在已经被认为是过时的而停止维护了。这个代码是由一个小的二进制组成，用于连接到传感器以及解释阅读和返回正确值的 Python 脚本。
|
||||
与我的项目放在一起的用于 [AM2302 传感器][10] 接口的软件已经更新了，并且我使用的原始代码现在应该已经过时了，停止维护了。这个代码是由一个小的二进制组成，用于连接到传感器以及解释读取并返回正确值的 Python 脚本。
|
||||
|
||||
![Raspberry Pi, sensor, and Python code][12]
|
||||
|
||||
树莓派、传感器、以及用于构建温度/湿度监视器的 Python 代码。
|
||||
*树莓派、传感器、以及用于构建温度/湿度监视器的 Python 代码。*
|
||||
|
||||
将传感器连接到树莓派，这些 Python 代码能够正确地返回温度和湿度读数。将 Python 连接到 MySQL 数据库很简单，并且也有大量的使用 `python-``mysql` 绑定的代码示例。因为我需要持续地监视温度和湿度，所以我写软件来实现这些。
|
||||
将传感器连接到树莓派，这些 Python 代码能够正确地返回温度和湿度读数。将 Python 连接到 MySQL 数据库很简单，并且也有大量的使用 python-mysql 绑定的代码示例。因为我需要持续地监视温度和湿度，所以我写软件来实现这些。
|
||||
|
||||
事实上，最终我用了两个解决方案，一是作为一个持续运行的进程，周期性（一般是间隔一分钟）地获取传感器数据，另一种是让 Python 脚本运行一次然后退出。我决定使用第二种方法，并使用 cron 去每分钟调用一次这个脚本。之所以选择这种方法的主要原因是，（通过循环实现的）持续的脚本偶尔会不返回读数，这将导致尝试读取传感器的进程出现聚集，最终可能会导致系统挂起而缺乏可用资源。
|
||||
事实上，最终我用了两个解决方案，一是作为一个持续运行的进程，周期性（一般是间隔一分钟）地获取传感器数据，另一种是让 Python 脚本运行一次然后退出。我决定使用第二种方法，并使用 cron 去每分钟调用一次这个脚本。之所以选择这种方法的主要原因是，（通过循环实现的）持续的脚本偶尔会不返回读数，这将导致尝试读取传感器的进程出现堆积，最终可能会导致系统挂起而缺乏可用资源。
|
||||
|
||||
我也找到了可以用程序来控制我的智能插头的一个 [Perl 脚本][13]。它是解决这种问题所需的一部分，因此当某些温度/湿度达到触发条件，将触发这个 Perl 脚本。在做了一些测试之后，我决定去设计一个独立的 `checking` 脚本，从 MySQL 去拉取最新的数据，然后根据返回的值去设置智能开关为开或关。将插头控制逻辑与传感器读取脚本分开，意味着它们是各自独立运行的，就算是传感器读取脚本写的有问题也没事。
|
||||
|
||||
@ -30,7 +33,7 @@
|
||||
|
||||
![Temperature and humidity chart][16]
|
||||
|
||||
过去六小时内测量到的温度和湿度
|
||||
*过去六小时内测量到的温度和湿度*
|
||||
|
||||
### 添加一个婴儿监视摄像头
|
||||
|
||||
@ -46,7 +49,7 @@
|
||||
|
||||
### 做最后的修饰
|
||||
|
||||
没有哪个树莓派项目都已经完成了还没有为它选择一个合适的外壳，并且它有各种零件。在大量搜索和比较之后，有了一个明确的 [赢家][20]：SmartPi 的乐高积木式外壳。乐高的兼容性可以让我去安装温度/湿度传感器和摄像头。下面是最终的成果图：
|
||||
没有哪个树莓派项目都已经完成了还没有为它选择一个合适的外壳，并且它有各种零件。在大量搜索和比较之后，有了一个显然的 [赢家][20]：SmartPi 的乐高积木式外壳。乐高的兼容性可以让我去安装温度/湿度传感器和摄像头。下面是最终的成果图：
|
||||
|
||||
|
||||
|
||||
@ -61,8 +64,6 @@
|
||||
* 我因此为我的第二个孩子设计了另外一个监视器。
|
||||
* 因为没有时间去折腾，我为我的第三个孩子购买了夜用摄像头。
|
||||
|
||||
|
||||
|
||||
想学习更多的东西吗？所有的代码都在 [我的 GitHub][4] 页面上。
|
||||
|
||||
想分享你的树莓派项目吗？[将你的故事和创意发送给我们][24]。
|
||||
@ -73,7 +74,7 @@ via: https://opensource.com/article/18/3/build-baby-monitor-raspberry-pi
|
||||
|
||||
作者：[Jonathan Ervine][a]
|
||||
译者：[qhwdw](https://github.com/qhwdw)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
@ -2,7 +2,8 @@
|
||||
======
|
||||
|
||||
|
||||
**Font Finder** 是旧的 [**Typecatcher**][1] 的 Rust 实现，用于从[**Google 的字体存档**][2]中轻松搜索和安装 Google Web 字体。它可以帮助你在 Linux 桌面上安装数百种免费和开源字体。如果你正在为你的 Web 项目和应用以及其他任何地方寻找好看的字体，Font Finder 可以轻松地为你提供。它是用 Rust 编程语言编写的免费开源 GTK3 应用程序。与使用 Python 编写的 Typecatcher 不同，Font Finder 可以按类别过滤字体，没有 Python 运行时依赖关系，并且有更好的性能和资源消耗。
|
||||
|
||||
Font Finder 是旧的 [Typecatcher][1] 的 Rust 实现，用于从 [Google 的字体存档][2]中轻松搜索和安装 Google Web 字体。它可以帮助你在 Linux 桌面上安装数百种免费和开源字体。如果你正在为你的 Web 项目和应用以及其他任何地方寻找好看的字体，Font Finder 可以轻松地为你提供。它是用 Rust 编程语言编写的自由、开源的 GTK3 应用程序。与使用 Python 编写的 Typecatcher 不同，Font Finder 可以按类别过滤字体，没有 Python 运行时依赖关系，并且有更好的性能和更低的资源消耗。
|
||||
|
||||
在这个简短的教程中，我们将看到如何在 Linux 中安装和使用 Font Finder。
|
||||
|
||||
@ -11,25 +12,25 @@
|
||||
由于 Fond Finder 是使用 Rust 语言编写的，因此你需要向下面描述的那样在系统中安装 Rust。
|
||||
|
||||
安装 Rust 后，运行以下命令安装 Font Finder：
|
||||
|
||||
```
|
||||
$ cargo install fontfinder
|
||||
|
||||
```
|
||||
|
||||
Font Finder 也可以从 [**flatpak app**][3] 安装。首先在你的系统中安装 Flatpak，如下面的链接所述。
|
||||
Font Finder 也可以从 [flatpak app][3] 安装。首先在你的系统中安装 Flatpak，如下面的链接所述。
|
||||
|
||||
然后，使用命令安装 Font Finder：
|
||||
|
||||
```
|
||||
$ flatpak install flathub io.github.mmstick.FontFinder
|
||||
|
||||
```
|
||||
|
||||
### 在 Linux 中使用 Font Finder 搜索和安装 Google Web 字体
|
||||
|
||||
你可以从程序启动器启动 Font Finder，也可以运行以下命令启动它。
|
||||
|
||||
```
|
||||
$ flatpak run io.github.mmstick.FontFinder
|
||||
|
||||
```
|
||||
|
||||
这是 Font Finder 默认界面的样子。
|
||||
@ -42,7 +43,7 @@ $ flatpak run io.github.mmstick.FontFinder
|
||||
|
||||
![][6]
|
||||
|
||||
要安装字体，只需选择它并点击顶部的 **Install** 按钮即可。
|
||||
要安装字体，只需选择它并点击顶部的 “Install” 按钮即可。
|
||||
|
||||
![][7]
|
||||
|
||||
@ -50,7 +51,7 @@ $ flatpak run io.github.mmstick.FontFinder
|
||||
|
||||
![][8]
|
||||
|
||||
同样，要删除字体，只需从 Font Finder 面板中选择它并单击 **Uninstall** 按钮。就这么简单！
|
||||
同样，要删除字体，只需从 Font Finder 面板中选择它并单击 “Uninstall” 按钮。就这么简单！
|
||||
|
||||
左上角的设置按钮（齿轮按钮）提供了切换到暗色预览的选项。
|
||||
|
||||
@ -62,8 +63,6 @@ $ flatpak run io.github.mmstick.FontFinder
|
||||
|
||||
干杯!
|
||||
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.ostechnix.com/font-finder-easily-search-and-install-google-web-fonts-in-linux/
|
||||
@ -71,7 +70,7 @@ via: https://www.ostechnix.com/font-finder-easily-search-and-install-google-web-
|
||||
作者：[SK][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
@ -1,14 +1,13 @@
|
||||
在 CentOS 6 系统上安装最新版 Python3 软件包的 3 种方法
|
||||
======
|
||||
|
||||
CentOS 克隆自 RHEL，无需付费即可使用。CentOS 是一个企业级标准的、前沿的操作系统，被超过 90% 的网络主机托管商采用，因为它提供了技术领先的服务器控制面板 cPanel/WHM。
|
||||
|
||||
该控制面板使得用户无需进入命令行即可通过其管理一切。
|
||||
|
||||
众所周知，RHEL 提供长期支持，出于稳定性考虑，不提供最新版本的软件包。
|
||||
|
||||
如果你想安装的最新版本软件包不在默认源中，你需要手动编译源码安装。
|
||||
|
||||
但手动编译安装的方式有不小的风险，即如果出现新版本，无法升级手动安装的软件包；你不得不重新手动安装。
|
||||
如果你想安装的最新版本软件包不在默认源中，你需要手动编译源码安装。但手动编译安装的方式有不小的风险，即如果出现新版本，无法升级手动安装的软件包；你不得不重新手动安装。
|
||||
|
||||
那么在这种情况下，安装最新版软件包的推荐方法和方案是什么呢？是的，可以通过为系统添加所需的第三方源来达到目的。
|
||||
|
||||
@ -18,19 +17,20 @@ CentOS 克隆自 RHEL，无需付费即可使用。CentOS 是一个企业级标
|
||||
|
||||
在本教程中，我们将向你展示，如何在 CentOS 6 操作系统上安装最新版本的 Python 3 软件包。
|
||||
|
||||
### 方法 1：使用 Software Collections 源 (SCL)
|
||||
### 方法 1：使用 Software Collections 源 （SCL）
|
||||
|
||||
SCL 源目前由 CentOS SIG 维护，除了重新编译构建 Red Hat 的 Software Collections 外，还额外提供一些它们自己的软件包。
|
||||
|
||||
该源中包含不少程序的更高版本，可以在不改变原有旧版本程序包的情况下安装，使用时需要通过 scl 命令调用。
|
||||
该源中包含不少程序的更高版本，可以在不改变原有旧版本程序包的情况下安装，使用时需要通过 `scl` 命令调用。
|
||||
|
||||
运行如下命令可以在 CentOS 上安装 SCL 源：
|
||||
|
||||
```
|
||||
# yum install centos-release-scl
|
||||
|
||||
```
|
||||
|
||||
检查可用的 Python 3 版本：
|
||||
|
||||
```
|
||||
# yum info rh-python35
|
||||
Loaded plugins: fastestmirror, security
|
||||
@ -38,149 +38,148 @@ Loading mirror speeds from cached hostfile
|
||||
* epel: ewr.edge.kernel.org
|
||||
* remi-safe: mirror.team-cymru.com
|
||||
Available Packages
|
||||
Name : rh-python35
|
||||
Arch : x86_64
|
||||
Version : 2.0
|
||||
Release : 2.el6
|
||||
Size : 0.0
|
||||
Repo : installed
|
||||
From repo : centos-sclo-rh
|
||||
Summary : Package that installs rh-python35
|
||||
License : GPLv2+
|
||||
Name : rh-python35
|
||||
Arch : x86_64
|
||||
Version : 2.0
|
||||
Release : 2.el6
|
||||
Size : 0.0
|
||||
Repo : installed
|
||||
From repo : centos-sclo-rh
|
||||
Summary : Package that installs rh-python35
|
||||
License : GPLv2+
|
||||
Description : This is the main package for rh-python35 Software Collection.
|
||||
|
||||
```
|
||||
|
||||
运行如下命令从 scl 源安装可用的最新版 python 3：
|
||||
运行如下命令从 `scl` 源安装可用的最新版 python 3：
|
||||
|
||||
```
|
||||
# yum install rh-python35
|
||||
|
||||
```
|
||||
|
||||
运行如下特殊的 scl 命令，在当前 shell 中启用安装的软件包：
|
||||
运行如下特殊的 `scl` 命令，在当前 shell 中启用安装的软件包：
|
||||
|
||||
```
|
||||
# scl enable rh-python35 bash
|
||||
|
||||
```
|
||||
|
||||
运行如下命令检查安装的 python3 版本：
|
||||
|
||||
```
|
||||
# python --version
|
||||
Python 3.5.1
|
||||
|
||||
```
|
||||
|
||||
运行如下命令获取系统已安装的 SCL 软件包列表：
|
||||
|
||||
```
|
||||
# scl -l
|
||||
rh-python35
|
||||
|
||||
```
|
||||
|
||||
### 方法 2：使用 EPEL 源 (Extra Packages for Enterprise Linux)
|
||||
### 方法 2：使用 EPEL 源 (Extra Packages for Enterprise Linux）
|
||||
|
||||
EPEL 是 Extra Packages for Enterprise Linux 的缩写，该源由 Fedora SIG (Special Interest Group) 维护。
|
||||
EPEL 是 Extra Packages for Enterprise Linux 的缩写，该源由 Fedora SIG （Special Interest Group）维护。
|
||||
|
||||
该 SIG 为企业级 Linux 创建、维护并管理一系列高品质补充软件包，受益的企业级 Linux 发行版包括但不限于红帽企业级 Linux (RHEL), CentOS, Scientific Linux (SL) 和 Oracle Linux (OL)等。
|
||||
该 SIG 为企业级 Linux 创建、维护并管理了一系列高品质补充软件包，受益的企业级 Linux 发行版包括但不限于红帽企业级 Linux （RHEL）、 CentOS、 Scientific Linux （SL） 和 Oracle Linux （OL）等。
|
||||
|
||||
EPEL 通常基于 Fedora 对应代码提供软件包，不会与企业级 Linux 发行版中的基础软件包冲突或替换其中的软件包。
|
||||
|
||||
**推荐阅读：** [在 RHEL, CentOS, Oracle Linux 或 Scientific Linux 上安装启用 EPEL 源][1]
|
||||
|
||||
EPEL 软件包位于 CentOS 的 Extra 源中，已经默认启用，故我们只需运行如下命令即可：
|
||||
|
||||
```
|
||||
# yum install epel-release
|
||||
|
||||
```
|
||||
|
||||
检查可用的 python 3 版本：
|
||||
|
||||
```
|
||||
# yum --disablerepo="*" --enablerepo="epel" info python34
|
||||
Loaded plugins: fastestmirror, security
|
||||
Loading mirror speeds from cached hostfile
|
||||
* epel: ewr.edge.kernel.org
|
||||
Available Packages
|
||||
Name : python34
|
||||
Arch : x86_64
|
||||
Version : 3.4.5
|
||||
Release : 4.el6
|
||||
Size : 50 k
|
||||
Repo : epel
|
||||
Summary : Version 3 of the Python programming language aka Python 3000
|
||||
URL : http://www.python.org/
|
||||
License : Python
|
||||
Name : python34
|
||||
Arch : x86_64
|
||||
Version : 3.4.5
|
||||
Release : 4.el6
|
||||
Size : 50 k
|
||||
Repo : epel
|
||||
Summary : Version 3 of the Python programming language aka Python 3000
|
||||
URL : http://www.python.org/
|
||||
License : Python
|
||||
Description : Python 3 is a new version of the language that is incompatible with the 2.x
|
||||
: line of releases. The language is mostly the same, but many details, especially
|
||||
: how built-in objects like dictionaries and strings work, have changed
|
||||
: considerably, and a lot of deprecated features have finally been removed.
|
||||
|
||||
|
||||
: line of releases. The language is mostly the same, but many details, especially
|
||||
: how built-in objects like dictionaries and strings work, have changed
|
||||
: considerably, and a lot of deprecated features have finally been removed.
|
||||
```
|
||||
|
||||
运行如下命令从 EPEL 源安装可用的最新版 python 3 软件包：
|
||||
|
||||
```
|
||||
# yum --disablerepo="*" --enablerepo="epel" install python34
|
||||
|
||||
```
|
||||
|
||||
默认情况下并不会安装 pip 和 setuptools，我们需要运行如下命令手动安装：
|
||||
默认情况下并不会安装 `pip` 和 `setuptools`，我们需要运行如下命令手动安装：
|
||||
|
||||
```
|
||||
# curl -O https://bootstrap.pypa.io/get-pip.py
|
||||
% Total % Received % Xferd Average Speed Time Time Time Current
|
||||
Dload Upload Total Spent Left Speed
|
||||
100 1603k 100 1603k 0 0 2633k 0 --:--:-- --:--:-- --:--:-- 4816k
|
||||
% Total % Received % Xferd Average Speed Time Time Time Current
|
||||
Dload Upload Total Spent Left Speed
|
||||
100 1603k 100 1603k 0 0 2633k 0 --:--:-- --:--:-- --:--:-- 4816k
|
||||
|
||||
# /usr/bin/python3.4 get-pip.py
|
||||
Collecting pip
|
||||
Using cached https://files.pythonhosted.org/packages/0f/74/ecd13431bcc456ed390b44c8a6e917c1820365cbebcb6a8974d1cd045ab4/pip-10.0.1-py2.py3-none-any.whl
|
||||
Using cached https://files.pythonhosted.org/packages/0f/74/ecd13431bcc456ed390b44c8a6e917c1820365cbebcb6a8974d1cd045ab4/pip-10.0.1-py2.py3-none-any.whl
|
||||
Collecting setuptools
|
||||
Downloading https://files.pythonhosted.org/packages/8c/10/79282747f9169f21c053c562a0baa21815a8c7879be97abd930dbcf862e8/setuptools-39.1.0-py2.py3-none-any.whl (566kB)
|
||||
100% |████████████████████████████████| 573kB 4.0MB/s
|
||||
Downloading https://files.pythonhosted.org/packages/8c/10/79282747f9169f21c053c562a0baa21815a8c7879be97abd930dbcf862e8/setuptools-39.1.0-py2.py3-none-any.whl (566kB)
|
||||
100% |████████████████████████████████| 573kB 4.0MB/s
|
||||
Collecting wheel
|
||||
Downloading https://files.pythonhosted.org/packages/1b/d2/22cde5ea9af055f81814f9f2545f5ed8a053eb749c08d186b369959189a8/wheel-0.31.0-py2.py3-none-any.whl (41kB)
|
||||
100% |████████████████████████████████| 51kB 8.0MB/s
|
||||
Downloading https://files.pythonhosted.org/packages/1b/d2/22cde5ea9af055f81814f9f2545f5ed8a053eb749c08d186b369959189a8/wheel-0.31.0-py2.py3-none-any.whl (41kB)
|
||||
100% |████████████████████████████████| 51kB 8.0MB/s
|
||||
Installing collected packages: pip, setuptools, wheel
|
||||
Successfully installed pip-10.0.1 setuptools-39.1.0 wheel-0.31.0
|
||||
|
||||
```
|
||||
|
||||
运行如下命令检查已安装的 python3 版本：
|
||||
|
||||
```
|
||||
# python3 --version
|
||||
Python 3.4.5
|
||||
|
||||
```
|
||||
|
||||
### 方法 3：使用 IUS 社区源
|
||||
|
||||
IUS 社区是 CentOS 社区批准的第三方 RPM 源，为企业级 Linux (RHEL 和 CentOS) 5, 6 和 7 版本提供最新上游版本的 PHP, Python, MySQL 等软件包。
|
||||
IUS 社区是 CentOS 社区批准的第三方 RPM 源，为企业级 Linux （RHEL 和 CentOS） 5、 6 和 7 版本提供最新上游版本的 PHP、 Python、 MySQL 等软件包。
|
||||
|
||||
IUS 社区源依赖于 EPEL 源，故我们需要先安装 EPEL 源，然后再安装 IUS 社区源。按照下面的步骤安装启用 EPEL 源和 IUS 社区源，利用该 RPM 系统安装软件包。
|
||||
|
||||
**推荐阅读：** [在 RHEL 或 CentOS 上安装启用 IUS 社区源][2]
|
||||
|
||||
EPEL 软件包位于 CentOS 的 Extra 源中，已经默认启用，故我们只需运行如下命令即可：
|
||||
|
||||
```
|
||||
# yum install epel-release
|
||||
|
||||
```
|
||||
|
||||
下载 IUS 社区源安装脚本：
|
||||
|
||||
```
|
||||
# curl 'https://setup.ius.io/' -o setup-ius.sh
|
||||
% Total % Received % Xferd Average Speed Time Time Time Current
|
||||
Dload Upload Total Spent Left Speed
|
||||
100 1914 100 1914 0 0 6563 0 --:--:-- --:--:-- --:--:-- 133k
|
||||
|
||||
% Total % Received % Xferd Average Speed Time Time Time Current
|
||||
Dload Upload Total Spent Left Speed
|
||||
100 1914 100 1914 0 0 6563 0 --:--:-- --:--:-- --:--:-- 133k
|
||||
```
|
||||
|
||||
安装启用 IUS 社区源：
|
||||
|
||||
```
|
||||
# sh setup-ius.sh
|
||||
|
||||
```
|
||||
|
||||
检查可用的 python 3 版本：
|
||||
|
||||
```
|
||||
# yum --enablerepo=ius info python36u
|
||||
Loaded plugins: fastestmirror, security
|
||||
@ -189,46 +188,45 @@ Loading mirror speeds from cached hostfile
|
||||
* ius: mirror.team-cymru.com
|
||||
* remi-safe: mirror.team-cymru.com
|
||||
Available Packages
|
||||
Name : python36u
|
||||
Arch : x86_64
|
||||
Version : 3.6.5
|
||||
Release : 1.ius.centos6
|
||||
Size : 55 k
|
||||
Repo : ius
|
||||
Summary : Interpreter of the Python programming language
|
||||
URL : https://www.python.org/
|
||||
License : Python
|
||||
Name : python36u
|
||||
Arch : x86_64
|
||||
Version : 3.6.5
|
||||
Release : 1.ius.centos6
|
||||
Size : 55 k
|
||||
Repo : ius
|
||||
Summary : Interpreter of the Python programming language
|
||||
URL : https://www.python.org/
|
||||
License : Python
|
||||
Description : Python is an accessible, high-level, dynamically typed, interpreted programming
|
||||
: language, designed with an emphasis on code readability.
|
||||
: It includes an extensive standard library, and has a vast ecosystem of
|
||||
: third-party libraries.
|
||||
:
|
||||
: The python36u package provides the "python3.6" executable: the reference
|
||||
: interpreter for the Python language, version 3.
|
||||
: The majority of its standard library is provided in the python36u-libs package,
|
||||
: which should be installed automatically along with python36u.
|
||||
: The remaining parts of the Python standard library are broken out into the
|
||||
: python36u-tkinter and python36u-test packages, which may need to be installed
|
||||
: separately.
|
||||
:
|
||||
: Documentation for Python is provided in the python36u-docs package.
|
||||
:
|
||||
: Packages containing additional libraries for Python are generally named with
|
||||
: the "python36u-" prefix.
|
||||
|
||||
: language, designed with an emphasis on code readability.
|
||||
: It includes an extensive standard library, and has a vast ecosystem of
|
||||
: third-party libraries.
|
||||
:
|
||||
: The python36u package provides the "python3.6" executable: the reference
|
||||
: interpreter for the Python language, version 3.
|
||||
: The majority of its standard library is provided in the python36u-libs package,
|
||||
: which should be installed automatically along with python36u.
|
||||
: The remaining parts of the Python standard library are broken out into the
|
||||
: python36u-tkinter and python36u-test packages, which may need to be installed
|
||||
: separately.
|
||||
:
|
||||
: Documentation for Python is provided in the python36u-docs package.
|
||||
:
|
||||
: Packages containing additional libraries for Python are generally named with
|
||||
: the "python36u-" prefix.
|
||||
```
|
||||
|
||||
运行如下命令从 IUS 源安装最新可用版本的 python 3 软件包：
|
||||
|
||||
```
|
||||
# yum --enablerepo=ius install python36u
|
||||
|
||||
```
|
||||
|
||||
运行如下命令检查已安装的 python3 版本：
|
||||
|
||||
```
|
||||
# python3.6 --version
|
||||
Python 3.6.5
|
||||
|
||||
```
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
@ -238,7 +236,7 @@ via: https://www.2daygeek.com/3-methods-to-install-latest-python3-package-on-cen
|
||||
作者：[PRAKASH SUBRAMANIAN][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[pinewall](https://github.com/pinewall)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
@ -0,0 +1,50 @@
|
||||
LikeCoin，一种给开放式许可的内容创作者的加密货币
|
||||
======
|
||||
|
||||
> 在共创协议下授权作品和挣钱这二者不再是一种争议。
|
||||
|
||||
|
||||
|
||||
传统观点认为，作家、摄影师、艺术家和其他创作者在<ruby>共创协议<rt>Creative Commons</rt></ruby>和其他开放许可下免费共享内容的不会得到报酬。这意味着大多数独立创作者无法通过在互联网上发布他们的作品来赚钱。而现在有了 [LikeCoin][1]：一个新的开源项目，旨在使这个让艺术家们经常为了贡献而不得不妥协或牺牲的常识成为过去。
|
||||
|
||||
LikeCoin 协议旨在通过创意内容获利，以便创作者可以专注于创造出色的内容而不是出售它。
|
||||
|
||||
该协议同样基于去中心化技术，它可以跟踪何时使用内容，并使用 LikeCoin 这种 [以太坊 ERC-20][2] 加密货币通证来奖励其创作者。它通过“<ruby>创造性共识<rt>Proof of Creativity</rt></ruby>”算法进行操作，该算法一部分根据作品收到多少个“喜欢”，一部分根据有多少作品衍生自它而分配 LikeCoin。由于开放式授权的内容有更多机会被重复使用并获得 LikeCoin 令牌，因此系统鼓励内容创作者在<ruby>共创协议<rt>Creative Commons</rt></ruby>许可下发布。
|
||||
|
||||
### 如何运作的
|
||||
|
||||
当通过 LikeCoin 协议上传创意片段时，内容创作者也将包括作品的元数据，包括作者信息及其 InterPlanetary 关联数据（[IPLD][3]）。这些数据构成了衍生作品的家族图谱；我们称作品与其衍生品之间的关系为“内容足迹”。这种结构使得内容的继承树可以很容易地追溯到原始作品。
|
||||
|
||||
LikeCoin 通证会使用作品的衍生历史记录的信息来将其分发给创作者。由于所有创意作品都包含作者钱包的元数据，因此相应的 LikeCoin 份额可以通过算法计算并分发。
|
||||
|
||||
LikeCoin 可以通过两种方式获得奖励：要么由想要通过支付给内容创建者来表示赞赏的个人直接给予，或通过 Creators Pool 收集观众的“赞”的并根据内容的 LikeRank 分配 LikeCoin。基于在 LikeCoin 协议中的内容追踪，LikeRank 衡量作品重要性（或者我们在这个场景下定义的创造性）。一般来说，一副作品有越多的衍生作品，创意内容的创新就越多，内容就会有更高的 LikeRank。 LikeRank 是内容创新性的量化者。
|
||||
|
||||
### 如何参与？
|
||||
|
||||
LikeCoin 仍然非常新，我们期望在 2018 年晚些时候推出我们的第一个去中心化程序来奖励<ruby>共创协议<rt>Creative Commons</rt></ruby>的内容，并与更大的社区无缝连接。
|
||||
|
||||
LikeCoin 的大部分代码都可以在 [LikeCoin GitHub][4] 仓库中通过 [GPL 3.0 许可证][5]访问。由于它仍处于积极开发阶段，一些实验代码尚未公开，但我们会尽快完成。
|
||||
|
||||
我们欢迎功能请求、拉取请求、复刻和星标。请参与我们在 Github 上的开发，并加入我们在 [Telegram][6] 的讨论组。我们同样在 [Medium][7]、[Facebook][8]、[Twitter][9] 和我们的网站 [like.co][1] 发布关于我们进展的最新消息。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/5/likecoin
|
||||
|
||||
作者：[Kin Ko][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://opensource.com/users/ckxpress
|
||||
[1]:https://like.co/
|
||||
[2]:https://en.wikipedia.org/wiki/ERC20
|
||||
[3]:https://ipld.io/
|
||||
[4]:https://github.com/likecoin
|
||||
[5]:https://www.gnu.org/licenses/gpl-3.0.en.html
|
||||
[6]:https://t.me/likecoin
|
||||
[7]:http://medium.com/likecoin
|
||||
[8]:http://fb.com/likecoin.foundation
|
||||
[9]:https://twitter.com/likecoin_fdn
|
||||
@ -1,11 +1,11 @@
|
||||
You-Get - 支持 80+ 网站的命令行多媒体下载器
|
||||
You-Get：支持 80 多个网站的命令行多媒体下载器
|
||||
======
|
||||
|
||||
|
||||
|
||||
你们大多数人可能用过或听说过 **Youtube-dl**，这个命令行程序可以从包括 Youtube 在内的 100+ 网站下载视频。我偶然发现了一个类似的工具，名字叫做 **"You-Get"**。这是一个 Python 编写的命令行下载器，可以让你从 Youtube，Facebook，Twitter 等很多热门网站下载图片，音频和视频。目前该下载器支持 80+ 站点，点击[**这里**][1]查看所有支持的网站。
|
||||
你们大多数人可能用过或听说过 **Youtube-dl**，这个命令行程序可以从包括 Youtube 在内的 100+ 网站下载视频。我偶然发现了一个类似的工具，名字叫做 **You-Get**。这是一个 Python 编写的命令行下载器，可以让你从 Youtube、Facebook、Twitter 等很多热门网站下载图片，音频和视频（LCTT 译注：首先，它们得是存在的网站）。目前该下载器支持 80+ 站点，点击[这里][1]查看所有支持的网站。
|
||||
|
||||
You-Get 不仅仅是一个下载器，它还可以将在线视频导流至你的视频播放器。更进一步，它还允许你在 Google 上搜索视频，只要给出搜索项，You-Get 使用 Google 搜索并下载相关度最高的视频。另外值得一提的特性是，它允许你暂停和恢复下载过程。它是一个完全自由、开源及跨平台的应用，适用于 Linux，MacOS 及 Windows。
|
||||
You-Get 不仅仅是一个下载器，它还可以将在线视频导流至你的视频播放器。更进一步，它还允许你在 Google 上搜索视频，只要给出搜索项，You-Get 使用 Google 搜索并下载相关度最高的视频。另外值得一提的特性是，它允许你暂停和恢复下载过程。它是一个完全自由、开源及跨平台的应用，适用于 Linux、MacOS 及 Windows。
|
||||
|
||||
### 安装 You-Get
|
||||
|
||||
@ -17,35 +17,36 @@ You-Get 不仅仅是一个下载器，它还可以将在线视频导流至你的
|
||||
|
||||
有多种方式安装 You-Get，其中官方推荐采用 pip 包管理器安装。如果你还没有安装 pip，可以参考如下链接：
|
||||
|
||||
[如何使用 pip 管理 Python 软件包][2]
|
||||
- [如何使用 pip 管理 Python 软件包][2]
|
||||
|
||||
需要注意的是，你需要安装 Python 3 版本的 pip。
|
||||
需要注意的是，你需要安装 Python 3 版本的 `pip`。
|
||||
|
||||
接下来，运行如下命令安装 You-Get：
|
||||
|
||||
```
|
||||
$ pip3 install you-get
|
||||
|
||||
```
|
||||
|
||||
可以使用命令升级 You-Get 至最新版本：
|
||||
|
||||
```
|
||||
$ pip3 install --upgrade you-get
|
||||
|
||||
```
|
||||
|
||||
### 开始使用 You-Get
|
||||
|
||||
使用方式与 Youtube-dl 工具基本一致。
|
||||
|
||||
**下载视频**
|
||||
#### 下载视频
|
||||
|
||||
下载视频，只需运行：
|
||||
|
||||
```
|
||||
$ you-get https://www.youtube.com/watch?v=HXaglTFJLMc
|
||||
|
||||
```
|
||||
|
||||
输出示例：
|
||||
|
||||
```
|
||||
site: YouTube
|
||||
title: The Last of The Mohicans by Alexandro Querevalú
|
||||
@ -58,22 +59,22 @@ stream:
|
||||
|
||||
Downloading The Last of The Mohicans by Alexandro Querevalú.mp4 ...
|
||||
100% ( 56.9/ 56.9MB) ├███████████████████████████████████████████████████████┤[1/1] 752 kB/s
|
||||
|
||||
```
|
||||
|
||||
下载视频前，你可能希望查看视频的细节信息。You-Get 提供了 **“–info”** 或 **“-i”** 参数，使用该参数可以获得给定视频所有可用的分辨率和格式。
|
||||
下载视频前，你可能希望查看视频的细节信息。You-Get 提供了 `–info` 或 `-i` 参数，使用该参数可以获得给定视频所有可用的分辨率和格式。
|
||||
|
||||
```
|
||||
$ you-get -i https://www.youtube.com/watch?v=HXaglTFJLMc
|
||||
|
||||
```
|
||||
|
||||
或者
|
||||
|
||||
```
|
||||
$ you-get --info https://www.youtube.com/watch?v=HXaglTFJLMc
|
||||
|
||||
```
|
||||
|
||||
输出示例如下：
|
||||
|
||||
```
|
||||
site: YouTube
|
||||
title: The Last of The Mohicans by Alexandro Querevalú
|
||||
@ -121,18 +122,18 @@ streams: # Available quality and codecs
|
||||
quality: hd720
|
||||
size: 56.9 MiB (59654303 bytes)
|
||||
# download-with: you-get --itag=22 [URL]
|
||||
|
||||
```
|
||||
|
||||
默认情况下，You-Get 会下载标记为 **DEFAULT** 的格式。如果你对格式或分辨率不满意，可以选择你喜欢的格式，使用格式对应的 itag 值即可。
|
||||
默认情况下，You-Get 会下载标记为 “DEFAULT” 的格式。如果你对格式或分辨率不满意，可以选择你喜欢的格式，使用格式对应的 itag 值即可。
|
||||
|
||||
```
|
||||
$ you-get --itag=244 https://www.youtube.com/watch?v=HXaglTFJLMc
|
||||
|
||||
```
|
||||
|
||||
**下载音频**
|
||||
#### 下载音频
|
||||
|
||||
执行下面的命令，可以从 soundcloud 网站下载音频：
|
||||
|
||||
```
|
||||
$ you-get 'https://soundcloud.com/uiceheidd/all-girls-are-same-999-prod-nick-mira'
|
||||
Site: SoundCloud.com
|
||||
@ -145,30 +146,30 @@ Downloading ALL GIRLS ARE THE SAME (PROD. NICK MIRA).mp3 ...
|
||||
|
||||
```
|
||||
|
||||
查看音频文件细节，使用 **-i** 参数：
|
||||
查看音频文件细节，使用 `-i` 参数：
|
||||
|
||||
```
|
||||
$ you-get -i 'https://soundcloud.com/uiceheidd/all-girls-are-same-999-prod-nick-mira'
|
||||
|
||||
```
|
||||
|
||||
**下载图片**
|
||||
#### 下载图片
|
||||
|
||||
运行如下命令下载图片：
|
||||
|
||||
```
|
||||
$ you-get https://pixabay.com/en/mountain-crumpled-cyanus-montanus-3393209/
|
||||
|
||||
```
|
||||
|
||||
You-Get 也可以下载网页中的全部图片：
|
||||
You-Get can also download all images from a web page.
|
||||
|
||||
```
|
||||
$ you-get https://www.ostechnix.com/pacvim-a-cli-game-to-learn-vim-commands/
|
||||
|
||||
```
|
||||
|
||||
**搜索视频**
|
||||
#### 搜索视频
|
||||
|
||||
你只需向 You-Get 传递一个任意的搜索项，而无需给出有效的 URL；You-Get 会使用 Google 搜索并下载与你给出搜索项最相关的视频。(LCTT 译注：Google 的机器人检测机制可能导致 503 报错导致该功能无法使用）。
|
||||
|
||||
你只需向 You-Get 传递一个任意的搜索项，而无需给出有效的 URL；You-Get 会使用 Google 搜索并下载与你给出搜索项最相关的视频。(译者注：Google 的机器人检测机制可能导致 503 报错导致该功能无法使用）。
|
||||
```
|
||||
$ you-get 'Micheal Jackson'
|
||||
Google Videos search:
|
||||
@ -184,53 +185,53 @@ stream:
|
||||
|
||||
Downloading Michael Jackson - Beat It (Official Video).webm ...
|
||||
100% ( 29.4/ 29.4MB) ├███████████████████████████████████████████████████████┤[1/1] 2 MB/s
|
||||
|
||||
```
|
||||
|
||||
**观看视频**
|
||||
#### 观看视频
|
||||
|
||||
You-Get 可以将在线视频导流至你的视频播放器或浏览器，跳过广告和评论部分。（LCTT 译注：使用 `-p` 参数需要对应的 vlc/chrominum 命令可以调用，一般适用于具有图形化界面的操作系统）。
|
||||
|
||||
You-Get 可以将在线视频导流至你的视频播放器或浏览器，跳过广告和评论部分。（译者注：使用 -p 参数需要对应的 vlc/chrominum 命令可以调用，一般适用于具有图形化界面的操作系统）。
|
||||
|
||||
以 VLC 视频播放器为例，使用如下命令在其中观看视频：
|
||||
|
||||
```
|
||||
$ you-get -p vlc https://www.youtube.com/watch?v=HXaglTFJLMc
|
||||
|
||||
```
|
||||
|
||||
或者
|
||||
|
||||
```
|
||||
$ you-get --player vlc https://www.youtube.com/watch?v=HXaglTFJLMc
|
||||
|
||||
```
|
||||
|
||||
类似地，将视频导流至以 chromium 为例的浏览器中，使用如下命令：
|
||||
|
||||
```
|
||||
$ you-get -p chromium https://www.youtube.com/watch?v=HXaglTFJLMc
|
||||
|
||||
```
|
||||
|
||||
![][3]
|
||||
|
||||
在上述屏幕截图中，可以看到并没有广告和评论部分，只是一个包含视频的简单页面。
|
||||
|
||||
**设置下载视频的路径及文件名**
|
||||
#### 设置下载视频的路径及文件名
|
||||
|
||||
默认情况下，使用视频标题作为默认文件名，下载至当前工作目录。当然，你可以按照你的喜好进行更改，使用 `–output-dir` 或 `-o` 参数可以指定路径，使用 `–output-filename` 或 `-O` 参数可以指定下载文件的文件名。
|
||||
|
||||
默认情况下，使用视频标题作为默认文件名，下载至当前工作目录。当然，你可以按照你的喜好进行更改，使用 **–output-dir/-o** 参数可以指定路径，使用 **–output-filename/-O** 参数可以指定下载文件的文件名。
|
||||
```
|
||||
$ you-get -o ~/Videos -O output.mp4 https://www.youtube.com/watch?v=HXaglTFJLMc
|
||||
|
||||
```
|
||||
|
||||
**暂停和恢复下载**
|
||||
#### 暂停和恢复下载
|
||||
|
||||
按 **CTRL+C** 可以取消下载。一个以 **.download** 为扩展名的临时文件会保存至输出路径。下次你使用相同的参数下载时，下载过程将延续上一次的过程。
|
||||
按 `CTRL+C` 可以取消下载。一个以 `.download` 为扩展名的临时文件会保存至输出路径。下次你使用相同的参数下载时，下载过程将延续上一次的过程。
|
||||
|
||||
当文件下载完成后，以 .download 为扩展名的临时文件会自动消失。如果这时你使用同样参数下载，You-Get 会跳过下载；如果你想强制重新下载，可以使用 **–force/-f** 参数。
|
||||
当文件下载完成后，以 `.download` 为扩展名的临时文件会自动消失。如果这时你使用同样参数下载，You-Get 会跳过下载；如果你想强制重新下载，可以使用 `–force` 或 `-f` 参数。
|
||||
|
||||
查看命令的帮助部分可以获取更多细节，命令如下：
|
||||
|
||||
```
|
||||
$ you-get --help
|
||||
|
||||
```
|
||||
|
||||
这次的分享到此结束，后续还会介绍更多的优秀工具，敬请期待！
|
||||
@ -246,7 +247,7 @@ via: https://www.ostechnix.com/you-get-a-cli-downloader-to-download-media-from-8
|
||||
作者：[SK][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[pinewall](https://github.com/pinewall)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
@ -1,132 +0,0 @@
|
||||
translating by MZqk
|
||||
|
||||
What’s next in IT automation: 6 trends to watch
|
||||
======
|
||||
|
||||
|
||||
|
||||
We’ve recently covered the [factors fueling IT automation][1], the [current trends][2] to watch as adoption grows, and [helpful tips][3] for those organizations just beginning to automate certain processes.
|
||||
|
||||
Oh, and we also shared expert advice on [how to make the case for automation][4] in your company, as well as [keys for long-term success][5].
|
||||
|
||||
Now, there’s just one question: What’s next? We asked a range of experts to share a peek into the not-so-distant future of [automation][6]. Here are six trends they advise IT leaders to monitor closely.
|
||||
|
||||
### 1. Machine learning matures
|
||||
|
||||
For all of the buzz around [machine learning][7] (and the overlapping phrase “self-learning systems”), it’s still very early days for most organizations in terms of actual implementations. Expect that to change, and for machine learning to play a significant role in the next waves of IT automation.
|
||||
|
||||
Mehul Amin, director of engineering for [Advanced Systems Concepts, Inc.][8], points to machine learning as one of the next key growth areas for IT automation.
|
||||
|
||||
“With the data that is developed, automation software can make decisions that otherwise might be the responsibility of the developer,” Amin says. “For example, the developer builds what needs to be executed, but identifying the best system to execute the processes might be [done] by software using analytics from within the system.”
|
||||
|
||||
That extends elsewhere in this same hypothetical system; Amin notes that machine learning can enable automated systems to provision additional resources when necessary to meet timelines or SLAs, as well as retire those resources when they’re no longer needed, and other possibilities.
|
||||
|
||||
Amin is certainly not alone.
|
||||
|
||||
“IT automation is moving towards self-learning,” says Kiran Chitturi, CTO architect at [Sungard Availability Services][9]. “Systems will be able to test and monitor themselves, enhancing business processes and software delivery.”
|
||||
|
||||
Chitturi points to automated testing as an example; test scripts are already in widespread adoption, but soon those automated testing processes may be more likely to learn as they go, developing, for example, wider recognition of how new code or code changes will impact production environments.
|
||||
|
||||
### 2. Artificial intelligence spawns automation opportunities
|
||||
|
||||
The same principles above hold true for the related (but separate) field of [artificial intelligence][10]. Depending on your definition of AI, it seems likely that machine learning will have the more significant IT impact in the near term (and we’re likely to see a lot of overlapping definitions and understandings of the two fields). Assume that emerging AI technologies will spawn new automation opportunities, too.
|
||||
|
||||
“The integration of artificial intelligence (AI) and machine learning capabilities is widely perceived as critical for business success in the coming years,” says Patrick Hubbard, head geek at [SolarWinds][11].
|
||||
|
||||
### 3. That doesn’t mean people are obsolete
|
||||
|
||||
Let’s try to calm those among us who are now hyperventilating into a paper bag: The first two trends don’t necessarily mean we’re all going to be out of a job.
|
||||
|
||||
It is likely to mean changes to various roles – and the creation of [new roles][12] altogether.
|
||||
|
||||
But in the foreseeable future, at least, you don’t need to practice bowing to your robot overlords.
|
||||
|
||||
“A machine can only consider the environment variables that it is given – it can’t choose to include new variables, only a human can do this today,” Hubbard explains. “However, for IT professionals this will necessitate the cultivation of AI- and automation-era skills such as programming, coding, a basic understanding of the algorithms that govern AI and machine learning functionality, and a strong security posture in the face of more sophisticated cyberattacks.”
|
||||
|
||||
Hubbard shares the example of new tools or capabilities such as AI-enabled security software or machine-learning applications that remotely spot maintenance needs in an oil pipeline. Both might improve efficiency and effectiveness; neither automatically replaces the people necessary for information security or pipeline maintenance.
|
||||
|
||||
“Many new functionalities still require human oversight,” Hubbard says. “In order for a machine to determine if something ‘predictive’ could become ‘prescriptive,’ for example, human management is needed.”
|
||||
|
||||
The same principle holds true even if you set machine learning and AI aside for a moment and look at IT automation more generally, especially in the software development lifecycle.
|
||||
|
||||
Matthew Oswalt, lead architect for automation at [Juniper Networks][13], points out that the fundamental reason IT automation is growing is that it is creating immediate value by reducing the amount of manual effort required to operate infrastructure.
|
||||
|
||||
Rather than responding to an infrastructure issue at 3 a.m. themselves, operations engineers can use event-driven automation to define their workflows ahead of time, as code.
|
||||
|
||||
“It also sets the stage for treating their operations workflows as code rather than easily outdated documentation or tribal knowledge,” Oswalt explains. “Operations staff are still required to play an active role in how [automation] tooling responds to events. The next phase of adopting automation is to put in place a system that is able to recognize interesting events that take place across the IT spectrum and respond in an autonomous fashion. Rather than responding to an infrastructure issue at 3 a.m. themselves, operations engineers can use event-driven automation to define their workflows ahead of time, as code. They can rely on this system to respond in the same way they would, at any time.”
|
||||
|
||||
### 4. Automation anxiety will decrease
|
||||
|
||||
Hubbard of SolarWinds notes that the term “automation” itself tends to spawn a lot of uncertainty and concern, not just in IT but across professional disciplines, and he says that concern is legitimate. But some of the attendant fears may be overblown, and even perpetuated by the tech industry itself. Reality might actually be the calming force on this front: When the actual implementation and practice of automation helps people realize #3 on this list, then we’ll see #4 occur.
|
||||
|
||||
“This year we’ll likely see a decrease in automation anxiety and more organizations begin to embrace AI and machine learning as a way to augment their existing human resources,” Hubbard says. “Automation has historically created room for more jobs by lowering the cost and time required to accomplish smaller tasks and refocusing the workforce on things that cannot be automated and require human labor. The same will be true of AI and machine learning.”
|
||||
|
||||
Automation will also decrease some anxiety around the topic most likely to increase an IT leader’s blood pressure: Security. As Matt Smith, chief architect, [Red Hat][14], recently [noted][15], automation will increasingly help IT groups reduce the security risks associated with maintenance tasks.
|
||||
|
||||
His advice: “Start by documenting and automating the interactions between IT assets during maintenance activities. By relying on automation, not only will you eliminate tasks that historically required much manual effort and surgical skill, you will also be reducing the risks of human error and demonstrating what’s possible when your IT organization embraces change and new methods of work. Ultimately, this will reduce resistance to promptly applying security patches. And it could also help keep your business out of the headlines during the next major security event.”
|
||||
|
||||
**[ Read the full article: [12 bad enterprise security habits to break][16]. ] **
|
||||
|
||||
### 5. Continued evolution of scripting and automation tools
|
||||
|
||||
Many organizations see the first steps toward increasing automation – usually in the form of scripting or automation tools (sometimes referred to as configuration management tools) – as "early days" work.
|
||||
|
||||
But views of those tools are evolving as the use of various automation technologies grows.
|
||||
|
||||
“There are many processes in the data center environment that are repetitive and subject to human error, and technologies such as [Ansible][17] help to ameliorate those issues,” says Mark Abolafia, chief operating officer at [DataVision][18]. “With Ansible, one can write a specific playbook for a set of actions and input different variables such as addresses, etc., to automate long chains of process that were previously subject to human touch and longer lead times.”
|
||||
|
||||
**[ Want to learn more about this aspect of Ansible? Read the related article:[Tips for success when getting started with Ansible][19]. ]**
|
||||
|
||||
Another factor: The tools themselves will continue to become more advanced.
|
||||
|
||||
“With advanced IT automation tools, developers will be able to build and automate workflows in less time, reducing error-prone coding,” says Amin of ASCI. “These tools include pre-built, pre-tested drag-and-drop integrations, API jobs, the rich use of variables, reference functionality, and object revision history.”
|
||||
|
||||
### 6. Automation opens new metrics opportunities
|
||||
|
||||
As we’ve said previously in this space, automation isn’t IT snake oil. It won’t fix busted processes or otherwise serve as some catch-all elixir for what ails your organization. That’s true on an ongoing basis, too: Automation doesn’t eliminate the need to measure performance.
|
||||
|
||||
**[ See our related article[DevOps metrics: Are you measuring what matters?][20] ]**
|
||||
|
||||
In fact, automation should open up new opportunities here.
|
||||
|
||||
“As more and more development activities – source control, DevOps pipelines, work item tracking – move to the API-driven platforms – the opportunity and temptation to stitch these pieces of raw data together to paint the picture of your organization's efficiency increases,” says Josh Collins, VP of architecture at [Janeiro Digital][21].
|
||||
|
||||
Collins thinks of this as a possible new “development organization metrics-in-a-box.” But don’t mistake that to mean machines and algorithms can suddenly measure everything IT does.
|
||||
|
||||
“Whether measuring individual resources or the team in aggregate, these metrics can be powerful – but should be balanced with a heavy dose of context,” Collins says. “Use this data for high-level trends and to affirm qualitative observations – not to clinically grade your team.”
|
||||
|
||||
**Want more wisdom like this, IT leaders?[Sign up for our weekly email newsletter][22].**
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://enterprisersproject.com/article/2018/3/what-s-next-it-automation-6-trends-watch
|
||||
|
||||
作者：[Kevin Casey][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://enterprisersproject.com/user/kevin-casey
|
||||
[1]:https://enterprisersproject.com/article/2017/12/5-factors-fueling-automation-it-now
|
||||
[2]:https://enterprisersproject.com/article/2017/12/4-trends-watch-it-automation-expands
|
||||
[3]:https://enterprisersproject.com/article/2018/1/getting-started-automation-6-tips
|
||||
[4]:https://enterprisersproject.com/article/2018/1/how-make-case-it-automation
|
||||
[5]:https://enterprisersproject.com/article/2018/1/it-automation-best-practices-7-keys-long-term-success
|
||||
[6]:https://enterprisersproject.com/tags/automation
|
||||
[7]:https://enterprisersproject.com/article/2018/2/how-spot-machine-learning-opportunity
|
||||
[8]:https://www.advsyscon.com/en-us/
|
||||
[9]:https://www.sungardas.com/en/
|
||||
[10]:https://enterprisersproject.com/tags/artificial-intelligence
|
||||
[11]:https://www.solarwinds.com/
|
||||
[12]:https://enterprisersproject.com/article/2017/12/8-emerging-ai-jobs-it-pros
|
||||
[13]:https://www.juniper.net/
|
||||
[14]:https://www.redhat.com/en?intcmp=701f2000000tjyaAAA
|
||||
[15]:https://enterprisersproject.com/article/2018/2/12-bad-enterprise-security-habits-break
|
||||
[16]:https://enterprisersproject.com/article/2018/2/12-bad-enterprise-security-habits-break?sc_cid=70160000000h0aXAAQ
|
||||
[17]:https://opensource.com/tags/ansible
|
||||
[18]:https://datavision.com/
|
||||
[19]:https://opensource.com/article/18/2/tips-success-when-getting-started-ansible?intcmp=701f2000000tjyaAAA
|
||||
[20]:https://enterprisersproject.com/article/2017/7/devops-metrics-are-you-measuring-what-matters?sc_cid=70160000000h0aXAAQ
|
||||
[21]:https://www.janeirodigital.com/
|
||||
[22]:https://enterprisersproject.com/email-newsletter?intcmp=701f2000000tsjPAAQ
|
||||
@ -0,0 +1,75 @@
|
||||
Linux vs. Unix: What's the difference?
|
||||
======
|
||||
|
||||
|
||||
If you are a software developer in your 20s or 30s, you've grown up in a world dominated by Linux. It has been a significant player in the data center for decades, and while it's hard to find definitive operating system market share reports, Linux's share of data center operating systems could be as high as 70%, with Windows variants carrying nearly all the remaining percentage. Developers using any major public cloud can expect the target system will run Linux. Evidence that Linux is everywhere has grown in recent years when you add in Android and Linux-based embedded systems in smartphones, TVs, automobiles, and many other devices.
|
||||
|
||||
Even so, most software developers, even those who have grown up during this venerable "Linux revolution" have at least heard of Unix. It sounds similar to Linux, and you've probably heard people use these terms interchangeably. Or maybe you've heard Linux called a "Unix-like" operating system.
|
||||
|
||||
So, what is this Unix? The caricatures speak of wizard-like "graybeards" sitting behind glowing green screens, writing C code and shell scripts, powered by old-fashioned, drip-brewed coffee. But Unix has a much richer history beyond those bearded C programmers from the 1970s. While articles detailing the history of Unix and "Unix vs. Linux" comparisons abound, this article will offer a high-level background and a list of major differences between these complementary worlds.
|
||||
|
||||
### Unix's beginnings
|
||||
|
||||
The history of Unix begins at AT&T Bell Labs in the late 1960s with a small team of programmers looking to write a multi-tasking, multi-user operating system for the PDP-7. Two of the most notable members of this team at the Bell Labs research facility were Ken Thompson and Dennis Ritchie. While many of Unix's concepts were derivative of its predecessor ([Multics][1]), the Unix team's decision early in the 1970s to rewrite this small operating system in the C language is what separated Unix from all others. At the time, operating systems were rarely, if ever, portable. Instead, by nature of their design and low-level source language, operating systems were tightly linked to the hardware platform for which they had been authored. By refactoring Unix on the C programming language, Unix could now be ported to many hardware architectures.
|
||||
|
||||
In addition to this new portability, which allowed Unix to quickly expand beyond Bell Labs to other research, academic, and even commercial uses, several key of the operating system's design tenets were attractive to users and programmers. For one, Ken Thompson's [Unix philosophy][2] became a powerful model of modular software design and computing. The Unix philosophy recommended utilizing small, purpose-built programs in combination to do complex overall tasks. Since Unix was designed around files and pipes, this model of "piping" inputs and outputs of programs together into a linear set of operations on the input is still in vogue today. In fact, the current cloud functions-as-a-service (FaaS)/serverless computing model owes much of its heritage to the Unix philosophy.
|
||||
|
||||
### Rapid growth and competition
|
||||
|
||||
Through the late 1970s and 80s, Unix became the root of a family tree that expanded across research, academia, and a growing commercial Unix operating system business. Unix was not open source software, and the Unix source code was licensable via agreements with its owner, AT&T. The first known software license was sold to the University of Illinois in 1975.
|
||||
|
||||
Unix grew quickly in academia, with Berkeley becoming a significant center of activity, given Ken Thompson's sabbatical there in the '70s. With all the activity around Unix at Berkeley, a new delivery of Unix software was born: the Berkeley Software Distribution, or BSD. Initially, BSD was not an alternative to AT&T's Unix, but an add-on with additional software and capabilities. By the time 2BSD (the Second Berkeley Software Distribution) arrived in 1979, Bill Joy, a Berkeley grad student, had added now-famous programs such as `vi` and the C shell (/bin/csh).
|
||||
|
||||
In addition to BSD, which became one of the most popular branches of the Unix family, Unix's commercial offerings exploded through the 1980s and into the '90s with names like HP-UX, IBM's AIX, Sun's Solaris, Sequent, and Xenix. As the branches grew from the original root, the "[Unix wars][3]" began, and standardization became a new focus for the community. The POSIX standard was born in 1988, as well as other standardization follow-ons via The Open Group into the 1990s.
|
||||
|
||||
Around this time AT&T and Sun released System V Release 4 (SVR4), which was adopted by many commercial vendors. Separately, the BSD family of operating systems had grown over the years, leading to some open source variations that were released under the now-familiar [BSD license][4] . This included FreeBSD, OpenBSD, and NetBSD, each with a slightly different target market in the Unix server industry. These Unix variants continue to have some usage today, although many have seen their server market share dwindle into the single digits (or lower). BSD may have the largest install base of any modern Unix system today. Also, every Apple Mac hardware unit shipped in recent history can be claimed by BSD, as its OS X (now macOS) operating system is a BSD-derivative.
|
||||
|
||||
While the full history of Unix and its academic and commercial variants could take many more pages, for the sake of our article focus, let's move on to the rise of Linux.
|
||||
|
||||
### Enter Linux
|
||||
|
||||
What we call the Linux operating system today is really the combination of two efforts from the early 1990s. Richard Stallman was looking to create a truly free and open source alternative to the proprietary Unix system. He was working on the utilities and programs under the name GNU, a recursive algorithm meaning "GNU's not Unix!" Although there was a kernel project underway, it turned out to be difficult going, and without a kernel, the free and open source operating system dream could not be realized. It was Linus Torvald's work—producing a working and viable kernel that he called Linux—that brought the complete operating system to life. Given that Linus was using several GNU tools (e.g., the GNU Compiler Collection, or [GCC][5]), the marriage of the GNU tools and the Linux kernel was a perfect match.
|
||||
|
||||
Linux distributions came to life with the components of GNU, the Linux kernel, MIT's X-Windows GUI, and other BSD components that could be used under the open source BSD license. The early popularity of distributions like Slackware and then Red Hat gave the "common PC user" of the 1990s access to the Linux operating system and, with it, many of the proprietary Unix system capabilities and utilities they used in their work or academic lives.
|
||||
|
||||
Because of the free and open source standing of all the Linux components, anyone could create a Linux distribution with a bit of effort, and soon the total number of distros reached into the hundreds. Today, [distrowatch.com][6] lists 312 unique Linux distributions available in some form. Of course, many developers utilize Linux either via cloud providers or by using popular free distributions like Fedora, Canonical's Ubuntu, Debian, Arch Linux, Gentoo, and many other variants. Commercial Linux offerings, which provide support on top of the free and open source components, became viable as many enterprises, including IBM, migrated from proprietary Unix to offering middleware and software solutions atop Linux. Red Hat built a model of commercial support around Red Hat Enterprise Linux, as did German provider SUSE with SUSE Linux Enterprise Server (SLES).
|
||||
|
||||
### Comparing Unix and Linux
|
||||
|
||||
So far, we've looked at the history of Unix and the rise of Linux and the GNU/Free Software Foundation underpinnings of a free and open source alternative to Unix. Let's examine the differences between these two operating systems that share much of the same heritage and many of the same goals.
|
||||
|
||||
From a user experience perspective, not very much is different! Much of the attraction of Linux was the operating system's availability across many hardware architectures (including the modern PC) and ability to use tools familiar to Unix system administrators and users.
|
||||
|
||||
Because of POSIX standards and compliance, software written on Unix could be compiled for a Linux operating system with a usually limited amount of porting effort. Shell scripts could be used directly on Linux in many cases. While some tools had slightly different flag/command-line options between Unix and Linux, many operated the same on both.
|
||||
|
||||
One side note is that the popularity of the macOS hardware and operating system as a platform for development that mainly targets Linux may be attributed to the BSD-like macOS operating system. Many tools and scripts meant for a Linux system work easily within the macOS terminal. Many open source software components available on Linux are easily available through tools like [Homebrew][7].
|
||||
|
||||
The remaining differences between Linux and Unix are mainly related to the licensing model: open source vs. proprietary, licensed software. Also, the lack of a common kernel within Unix distributions has implications for software and hardware vendors. For Linux, a vendor can create a device driver for a specific hardware device and expect that, within reason, it will operate across most distributions. Because of the commercial and academic branches of the Unix tree, a vendor might have to write different drivers for variants of Unix and have licensing and other concerns related to access to an SDK or a distribution model for the software as a binary device driver across many Unix variants.
|
||||
|
||||
As both communities have matured over the past decade, many of the advancements in Linux have been adopted in the Unix world. Many GNU utilities were made available as add-ons for Unix systems where developers wanted features from GNU programs that aren't part of Unix. For example, IBM's AIX offered an AIX Toolbox for Linux Applications with hundreds of GNU software packages (like Bash, GCC, OpenLDAP, and many others) that could be added to an AIX installation to ease the transition between Linux and Unix-based AIX systems.
|
||||
|
||||
Proprietary Unix is still alive and well and, with many major vendors promising support for their current releases well into the 2020s, it goes without saying that Unix will be around for the foreseeable future. Also, the BSD branch of the Unix tree is open source, and NetBSD, OpenBSD, and FreeBSD all have strong user bases and open source communities that may not be as visible or active as Linux, but are holding their own in recent server share reports, with well above the proprietary Unix numbers in areas like web serving.
|
||||
|
||||
Where Linux has shown a significant advantage over proprietary Unix is in its availability across a vast number of hardware platforms and devices. The Raspberry Pi, popular with hobbyists and enthusiasts, is Linux-driven and has opened the door for an entire spectrum of IoT devices running Linux. We've already mentioned Android devices, autos (with Automotive Grade Linux), and smart TVs, where Linux has large market share. Every cloud provider on the planet offers virtual servers running Linux, and many of today's most popular cloud-native stacks are Linux-based, whether you're talking about container runtimes or Kubernetes or many of the serverless platforms that are gaining popularity.
|
||||
|
||||
One of the most revealing representations of Linux's ascendancy is Microsoft's transformation in recent years. If you told software developers a decade ago that the Windows operating system would "run Linux" in 2016, most of them would have laughed hysterically. But the existence and popularity of the Windows Subsystem for Linux (WSL), as well as more recently announced capabilities like the Windows port of Docker, including LCOW (Linux containers on Windows) support, are evidence of the impact that Linux has had—and clearly will continue to have—across the software world.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/5/differences-between-linux-and-unix
|
||||
|
||||
作者：[Phil Estes][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://opensource.com/users/estesp
|
||||
[1]:https://en.wikipedia.org/wiki/Multics
|
||||
[2]:https://en.wikipedia.org/wiki/Unix_philosophy
|
||||
[3]:https://en.wikipedia.org/wiki/Unix_wars
|
||||
[4]:https://en.wikipedia.org/wiki/BSD_licenses
|
||||
[5]:https://en.wikipedia.org/wiki/GNU_Compiler_Collection
|
||||
[6]:https://distrowatch.com/
|
||||
[7]:https://brew.sh/
|
||||
@ -0,0 +1,175 @@
|
||||
The Best Linux Tools for Teachers and Students
|
||||
======
|
||||
Linux is a platform ready for everyone. If you have a niche, Linux is ready to meet or exceed the needs of said niche. One such niche is education. If you are a teacher or a student, Linux is ready to help you navigate the waters of nearly any level of the educational system. From study aids, to writing papers, to managing classes, to running an entire institution, Linux has you covered.
|
||||
|
||||
If you’re unsure how, let me introduce you to a few tools Linux has at the ready. Some of these tools require little to no learning curve, whereas others require a full blown system administrator to install, setup, and manage. We’ll start with the simple and make our way to the complex.
|
||||
|
||||
### Study aids
|
||||
|
||||
Everyone studies a bit differently and every class requires a different type and level of studying. Fortunately, Linux has plenty of study aids. Let’s take a look at a few examples:
|
||||
|
||||
Flash Cards ─ [KWordQuiz][1] (Figure 1) is one of the many flashcard applications available for the Linux platform. KWordQuiz uses the kvtml file format and you can download plenty of pre-made, contributed files to use [here][2]. KWordQuiz is part of the KDE desktop environment, but can be installed on other desktops (KDE dependencies will be installed alongside the flashcard app).
|
||||
|
||||
|
||||
|
||||
### Language tools
|
||||
|
||||
Thanks to an ever-shrinking world, foreign language has become a crucial element of education. You’ll find plenty of language tools, including [Kiten][3] (Figure 2) the kanji browser for the KDE desktop.
|
||||
|
||||
|
||||
|
||||
If Japanese isn’t your language, you could try [Jargon Informatique][4]. This dictionary is entirely in French and, so if you’re new to the language, you might want to stick with something like [Google Translate][5].
|
||||
|
||||
### Writing Aids/ Note Taking
|
||||
|
||||
Linux has everything you need to keep notes on a subject and write those term papers. Let’s start with taking notes. If you’re familiar with Microsoft OneNote, you'll love [BasKet Note Pads][6]. With this app, you can create baskets for subjects and add just about anything ─ notes, links, images, cross references (to other baskets ─ Figure 3), app launchers, load from file, and more.
|
||||
|
||||
|
||||
|
||||
You can create baskets that are free-form, so elements can be moved around to suit your need. If you prefer a more ordered feel, create a columned basket to retain those notes walled in.
|
||||
|
||||
Of course, the mother of all writing aids for Linux would be [LibreOffice][7]. The default office suite on most Linux distributions, LibreOffice has your text documents, spreadsheets, presentations, databases, formula, and drawing covered.
|
||||
|
||||
The one caveat to using LibreOffice in an educational environment, is that you will most likely have to save your documents in the MS Office format.
|
||||
|
||||
### Education-specific distribution
|
||||
|
||||
With all of this said about Linux applications geared toward the student in mind, it might behoove you to take a look at one of the distributions created specifically for education. The best in breed is [Edubuntu][8]. This grassroots Linux distribution aims at getting Linux into schools, homes, and communities. Edubuntu uses the default Ubuntu desktop (the Unity shell) and adds the following software:
|
||||
|
||||
|
||||
+ KDE Education Suite
|
||||
|
||||
+ GCompris
|
||||
|
||||
+ Celestia
|
||||
|
||||
+ Tux4Kids
|
||||
|
||||
+ Epoptes
|
||||
|
||||
+ LTSP
|
||||
|
||||
+ GBrainy
|
||||
|
||||
+ and much more.
|
||||
|
||||
Edubuntu isn’t the only game in town. If you’d rather test other education-specific Linux distributions, here’s the short list:
|
||||
|
||||
|
||||
+ Debian-Edu
|
||||
|
||||
+ Fedora Education Spin
|
||||
|
||||
+ Guadalinux-Edu
|
||||
|
||||
+ OpenSuse-Edu
|
||||
|
||||
+ Qimo for Kids
|
||||
|
||||
+ Uberstudent.
|
||||
|
||||
### Classroom/institutional administration
|
||||
|
||||
This is where the Linux platform really shines. There are a number of tools geared specifically for administering. Let’s first look at tools specific to the classroom.
|
||||
|
||||
[iTalc][9] is a powerful didactical environment for the classroom. With this tool, teachers can view and control students desktops (supporting Linux and Windows). The iTalc system allows teachers to view what’s happening on a student's desktop, take control of their desktop, lock their desktop, show demonstrations to desktops, power on/off desktops, send text messages to students' desktops, and much more.
|
||||
|
||||
[aTutor][10] (Figure 4) is an open source Learning Management System (LMS) focused on developing online courses and e-learning content. Where aTutor really shines is the creation and management of online tests and quizzes. Of course, aTutor is not limited to testing purposes. With this powerful software, students and teachers can enjoy:
|
||||
|
||||
* Social networking
|
||||
|
||||
* Profiles
|
||||
|
||||
* Messaging
|
||||
|
||||
* Adaptive navigation
|
||||
|
||||
* Work groups
|
||||
|
||||
* File storage
|
||||
|
||||
* Group blogs
|
||||
|
||||
* and much more.
|
||||
|
||||
|
||||
|
||||
|
||||
Course material is easy to create and deploy (you can even assign tests/quizzes to specific study groups).
|
||||
|
||||
[Moodle][11] is one of the most widely used educational management software titles available. With Moodle you can manage, teach, learn, and even participate in your child’s education. This powerhouse software offers collaborative tools for teachers and students, exams, calendars, forums, file management, course management (Figure 5), notifications, progress tracking, mass enrollment, bulk course creation, attendance, and much more.
|
||||
|
||||
|
||||
|
||||
[OpenSIS][12] stands for Open Source Student Information System and does a great job of managing your educational institution. There is a free community edition, but even with the paid version you can look forward to reducing ownership costs for a school district by up to 75 percent (when compared to proprietary solutions).
|
||||
|
||||
OpenSIS includes the following features/modules:
|
||||
|
||||
* Attendance (Figure 6)
|
||||
|
||||
* Contact information
|
||||
|
||||
* Student demographics
|
||||
|
||||
* Gradebook
|
||||
|
||||
* Scheduling
|
||||
|
||||
* Health records
|
||||
|
||||
* Report cards.
|
||||
|
||||
|
||||
|
||||
|
||||
There are four editions of OpenSIS. Check out the feature comparison matrix [here][13].
|
||||
|
||||
[vufind][14] is an outstanding library management system that allows students and teachers to easily browse for library resources such as:
|
||||
|
||||
* Catalog Records
|
||||
|
||||
* Locally Cached Journals
|
||||
|
||||
* Digital Library Items
|
||||
|
||||
* Institutional Repository
|
||||
|
||||
* Institutional Bibliography
|
||||
|
||||
* Other Library Collections and Resources.
|
||||
|
||||
|
||||
|
||||
|
||||
The vufind system allows user login where authenticated users can save resources for quick recall and enjoy “more like this” results.
|
||||
|
||||
This list just barely scratches the surface of what is available for Linux in the educational arena. And, as you might expect, each tool is highly customizable and open source ─ so if the software doesn’t precisely meet your needs, you are free (in most cases) to modify the source and change it.
|
||||
|
||||
Linux and education go hand in hand. Whether you are a teacher, a student, or an administrator, you’ll find plenty of tools to help make the institution of education open, flexible, and powerful.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.linux.com/news/best-linux-tools-teachers-and-students
|
||||
|
||||
作者：[Jack Wallen][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://www.linux.com/users/jlwallen
|
||||
[1]:https://edu.kde.org/kwordquiz/
|
||||
[2]:http://kde-files.org/index.php?xcontentmode=694
|
||||
[3]:https://edu.kde.org/kiten/
|
||||
[4]:http://jargon.asher256.com/index.php
|
||||
[5]:https://translate.google.com/
|
||||
[6]:http://basket.kde.org/
|
||||
[7]:http://www.libreoffice.com
|
||||
[8]:http://www.edubuntu.org/
|
||||
[9]:http://italc.sourceforge.net/
|
||||
[10]:http://www.atutor.ca/
|
||||
[11]:https://moodle.org/
|
||||
[12]:http://www.opensis.com/
|
||||
[13]:http://www.opensis.com/compare_edition.php
|
||||
[14]:http://vufind-org.github.io/vufind/
|
||||
258
sources/tech/20180205 Writing eBPF tracing tools in Rust.md
Normal file
258
sources/tech/20180205 Writing eBPF tracing tools in Rust.md
Normal file
@ -0,0 +1,258 @@
|
||||
Writing eBPF tracing tools in Rust
|
||||
============================================================
|
||||
|
||||
tl;dr: I made an experimental Rust repository that lets you write BPF tracing tools from Rust! It’s at [https://github.com/jvns/rust-bcc][4] or [https://crates.io/crates/bcc][5], and has a couple of hopefully easy to understand examples. It turns out that writing BPF-based tracing tools in Rust is really easy (in some ways easier than doing the same things in Python). In this post I’ll explain why I think this is useful/important.
|
||||
|
||||
For a long time I’ve been interested in the [BPF compiler collection][6], a C -> BPF compiler, C library, and Python bindings to make it easy to write tools like:
|
||||
|
||||
* [opensnoop][1] (spies on which files are being opened)
|
||||
|
||||
* [tcplife][2] (track length of TCP connections)
|
||||
|
||||
* [cpudist][3] (count how much time every program spends on- and off-CPU)
|
||||
|
||||
and a lot more. The list of available tools in [the /tools directory][7] is really impressive and I could write a whole blog post about that. If you’re familiar with dtrace – the idea is that BCC is a little bit like dtrace, and in fact there’s a dtrace-like language [named ply][8] implemented with BPF.
|
||||
|
||||
This blog post isn’t about `ply` or the great BCC tools though – it’s about what tools we need to build more complicated/powerful BPF-based programs.
|
||||
|
||||
### What does the BPF compiler collection let you do?
|
||||
|
||||
Here’s a quick overview of what BCC lets you do:
|
||||
|
||||
* compile BPF programs from C into eBPF bytecode.
|
||||
|
||||
* attach this eBPF bytecode to a userspace function or kernel function (as a “uprobe” / “kprobe”) or install it as XDP
|
||||
|
||||
* communicate with the eBPF bytecode to get information with it
|
||||
|
||||
A basic example of using BCC is this [strlen_count.py][9] program and I think it’s useful to look at this program to understand how BCC works and how you might be able to implement more advanced tools.
|
||||
|
||||
First, there’s an eBPF program. This program is going to be attached to the `strlen` function from libc (the C standard library) – every time we call `strlen`, this code will be run.
|
||||
|
||||
This eBPF program
|
||||
|
||||
* gets the first argument to the `strlen` function (the address of a string)
|
||||
|
||||
* reads the first 80 characters of that string (using `bpf_probe_read`)
|
||||
|
||||
* increments a counter in a hashmap (basically `counts[str] += 1`)
|
||||
|
||||
The result is that you can count every call to `strlen`. Here’s the eBPF program:
|
||||
|
||||
```
|
||||
struct key_t {
|
||||
char c[80];
|
||||
};
|
||||
BPF_HASH(counts, struct key_t);
|
||||
int count(struct pt_regs *ctx) {
|
||||
if (!PT_REGS_PARM1(ctx))
|
||||
return 0;
|
||||
struct key_t key = {};
|
||||
u64 zero = 0, *val;
|
||||
bpf_probe_read(&key.c, sizeof(key.c), (void *)PT_REGS_PARM1(ctx));
|
||||
val = counts.lookup_or_init(&key, &zero);
|
||||
(*val)++;
|
||||
return 0;
|
||||
};
|
||||
|
||||
```
|
||||
|
||||
After that program is compiled, there’s a Python part which does `b.attach_uprobe(name="c", sym="strlen", fn_name="count")` – it tells the Linux kernel to actually attach the compiled BPF to the `strlen` function so that it runs every time `strlen` runs.
|
||||
|
||||
The really exciting thing about eBPF is what comes next – there’s no use keeping a hashmap of string counts if you can’t access it! BPF has a number of data structures that let you share information between BPF programs (that run in the kernel / in uprobes) and userspace.
|
||||
|
||||
So in this case the Python program accesses this `counts` data structure.
|
||||
|
||||
### BPF data structures: hashmaps, buffers, and more!
|
||||
|
||||
There’s a great list of available BPF data structures in the [BCC reference guide][10].
|
||||
|
||||
There are basically 2 kinds of BPF data structures – data structures suitable for storing statistics (BPF_HASH, BPF_HISTOGRAM etc), and data structures suitable for storing events (like BPF_PERF_MAP) where you send a stream of events to a userspace program which then displays them somehow.
|
||||
|
||||
There are a lot of interesting BPF data structures (like a trie!) and I haven’t fully worked out what all of the possibilities are with them yet :)
|
||||
|
||||
### What I’m interested in: BPF for profiling & tracing
|
||||
|
||||
Okay!! We’re done with the background, let’s talk about why I’m interested in BCC/BPF right now.
|
||||
|
||||
I’m interested in using BPF to implement profiling/tracing tools for dynamic programming languages, specifically tools to do things like “trace all memory allocations in this Ruby program”. I think it’s exciting that you can say “hey, run this tiny bit of code every time a Ruby object is allocated” and get data back about ongoing allocations!
|
||||
|
||||
### Rust: a way to build more powerful BPF-based tools
|
||||
|
||||
The issue I see with the Python BPF libraries (which are GREAT, of course) is that while they’re perfect for building tools like `tcplife` which track tcp connnection lengths, once you want to start doing more complicated experiments like “stream every memory allocation from this Ruby program, calculate some metadata about it, query the original process to find out the class name for that address, and display a useful summary”, Python doesn’t really cut it.
|
||||
|
||||
So I decided to spend 4 days trying to build a BCC library for Rust that lets you attach + interact with BPF programs from Rust!
|
||||
|
||||
Basically I worked on porting [https://github.com/iovisor/gobpf][11] (a go BCC library) to Rust.
|
||||
|
||||
The easiest and most exciting way to explain this is to show an example of what using the library looks like.
|
||||
|
||||
### Rust example 1: strlen
|
||||
|
||||
Let’s start with the strlen example from above. Here’s [strlen.rs][12] from the examples!
|
||||
|
||||
Compiling & attaching the `strlen` code is easy:
|
||||
|
||||
```
|
||||
let mut module = BPF::new(code)?;
|
||||
let uprobe_code = module.load_uprobe("count")?;
|
||||
module.attach_uprobe("/lib/x86_64-linux-gnu/libc.so.6", "strlen", uprobe_code, -1 /* all PIDs */)?;
|
||||
let table = module.table("counts");
|
||||
|
||||
```
|
||||
|
||||
This table contains a hashmap mapping strings to counts. So we need to iterate over that table and print out the keys and values. This is pretty simple: it looks like this.
|
||||
|
||||
```
|
||||
let iter = table.into_iter();
|
||||
for e in iter {
|
||||
// key and value are each a Vec<u8> so we need to transform them into a string and
|
||||
// a u64 respectively
|
||||
let key = get_string(&e.key);
|
||||
let value = Cursor::new(e.value).read_u64::<NativeEndian>().unwrap();
|
||||
println!("{:?} {:?}", key, value);
|
||||
}
|
||||
|
||||
```
|
||||
|
||||
Basically all the data that comes out of a BPF program is an opaque `Vec<u8>`right now, so you need to figure out how to decode them yourself. Luckily decoding binary data is something that Rust is quite good at – the `byteorder`crate lets you easily decode `u64`s, and translating a vector of bytes into a String is easy (I wrote a quick `get_string` helper function to do that).
|
||||
|
||||
I thought this was really nice because the code for this program in Rust is basically exactly the same as the corresponding Python version. So it very pretty approachable to start doing experiments and seeing what’s possible.
|
||||
|
||||
### Reading perf events from Rust
|
||||
|
||||
The next thing I wanted to do after getting this `strlen` example to work in rust was to handle events!!
|
||||
|
||||
Events are a little different / more complicated. The way you stream events in a BCC program is – it uses `perf_event_open` to create a ring buffer where the events get stored.
|
||||
|
||||
Dealing with events from a perf ring buffer normally is a huge pain because perf has this complicated data structure. The C BCC library makes this easier for you by letting you specify a C callback that gets called on every new event, and it handles dealing with perf. This is super helpful. To make this work with Rust, the `rust-bcc` library lets you pass in a Rust closure to run on every event.
|
||||
|
||||
### Rust example 2: opensnoop.rs (events!!)
|
||||
|
||||
To make sure reading BPF events actually worked, I implemented a basic version of `opensnoop.py` from the iovisor bcc tools: [opensnoop.rs][13].
|
||||
|
||||
I won’t walk through the [C code][14] in this case because there’s a lot of it but basically the eBPF C part generates an event every time a file is opened on the system. I copied the C code verbatim from [opensnoop.py][15].
|
||||
|
||||
Here’s the type of the event that’s generated by the BPF code:
|
||||
|
||||
```
|
||||
#[repr(C)]
|
||||
struct data_t {
|
||||
id: u64, // pid + thread id
|
||||
ts: u64,
|
||||
ret: libc::c_int,
|
||||
comm: [u8; 16], // process name
|
||||
fname: [u8; 255], // filename
|
||||
}
|
||||
|
||||
```
|
||||
|
||||
The Rust part starts out by compiling BPF code & attaching kprobes (to the `open`system call in the kernel, `do_sys_open`). I won’t paste that code here because it’s basically the same as the `strlen` example. What happens next is the new part: we install a callback with a Rust closure on the `events` table, and then call `perf_map.poll(200)` in a loop. The design of the BCC library is a little confusing to me still, but you need to repeatedly poll the perf reader objects to make sure that the callbacks you installed actually get called.
|
||||
|
||||
```
|
||||
let table = module.table("events");
|
||||
let mut perf_map = init_perf_map(table, perf_data_callback)?;
|
||||
loop {
|
||||
perf_map.poll(200);
|
||||
}
|
||||
|
||||
```
|
||||
|
||||
This is the callback code I wrote, that gets called every time. Again, it takes an opaque `Vec<u8>` event and translates it into a `data_t` struct to print it out. Doing this is kind of annoying (I actually called `libc::memcpy` which is Not Encouraged Rust Practice), I need to figure out a less gross/unsafe way to do that. The really nice thing is that if you put `#[repr(C)]` on your Rust structs it represents them in memory the exact same way C will represent that struct. So it’s quite easy to share data structures between Rust and C.
|
||||
|
||||
```
|
||||
fn perf_data_callback() -> Box<Fn(Vec<u8>)> {
|
||||
Box::new(|x| {
|
||||
// This callback
|
||||
let data = parse_struct(&x);
|
||||
println!("{:-7} {:-16} {}", data.id >> 32, get_string(&data.comm), get_string(&data.fname));
|
||||
})
|
||||
}
|
||||
|
||||
```
|
||||
|
||||
You might notice that this is actually a weird function that returns a callback – this is because I needed to install 4 callbacks (1 per CPU), and in stable Rust you can’t copy closures yet.
|
||||
|
||||
output
|
||||
|
||||
Here’s what the output of that `opensnoop` program looks like!
|
||||
|
||||
This is kind of meta – these are the files that were being opened on my system when I saved this blog post :). You can see that git is looking at some files, vim is saving a file, and my static site generator Hugo is opening the changed file so that it can update the site. Neat!
|
||||
|
||||
```
|
||||
PID COMMAND FILENAME
|
||||
8519 git /home/bork/work/homepage/.gitmodules
|
||||
8519 git /home/bork/.gitconfig
|
||||
8519 git .git/config
|
||||
22877 vim content/post/2018-02-05-writing-ebpf-programs-in-rust.markdown
|
||||
22877 vim .
|
||||
7312 hugo /home/bork/work/homepage/content/post/2018-02-05-writing-ebpf-programs-in-rust.markdown
|
||||
7312 hugo /home/bork/work/homepage/content/post/2018-02-05-writing-ebpf-programs-in-rust.markdown
|
||||
|
||||
```
|
||||
|
||||
### using rust-bcc to implement Ruby experiments
|
||||
|
||||
Now that I have this basic library that I can use I can get counts + stream events in Rust, I’m excited about doing some experiments with making BCC programs in Rust that talk to Ruby programs!
|
||||
|
||||
The first experiment (that I blogged about last week) is [count-ruby-allocs.rs][16]which prints out a live count of current allocation activity. Here’s an example of what it prints out: (the numbers are counts of the number of objects allocated of that type so far).
|
||||
|
||||
```
|
||||
RuboCop::Token 53
|
||||
RuboCop::Token 112
|
||||
MatchData 246
|
||||
Parser::Source::Rang 255
|
||||
Proc 323
|
||||
Enumerator 328
|
||||
Hash 475
|
||||
Range 1210
|
||||
??? 1543
|
||||
String 3410
|
||||
Array 7879
|
||||
Total allocations since we started counting: 16932
|
||||
Allocations this second: 954
|
||||
|
||||
```
|
||||
|
||||
### Related work
|
||||
|
||||
Geoffrey Couprie is interested in building more advanced BPF tracing tools with Rust too and wrote a great blog post with a cool proof of concept: [Compiling to eBPF from Rust][17].
|
||||
|
||||
I think the idea of not requiring the user to compile the BPF program is exciting, because you could imagine distributing a statically linked Rust binary (which links in libcc.so) with a pre-compiled BPF program that the binary just installs and then uses to do cool stuff.
|
||||
|
||||
Also there’s another Rust BCC library at [https://bitbucket.org/photoszzt/rust-bpf/][18] at which has a slightly different set of capabilities than [jvns/rust-bcc][19] (going to spend some time looking at that one later, I just found about it like 30 minutes ago :)).
|
||||
|
||||
### that’s it for now
|
||||
|
||||
This crate is still extremely sketchy and there are bugs & missing features but I wanted to put it on the internet because I think the examples of what you can do with it are really exciting!!
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://jvns.ca/blog/2018/02/05/rust-bcc/
|
||||
|
||||
作者：[Julia Evans ][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://jvns.ca/about/
|
||||
[1]:https://github.com/iovisor/bcc/blob/master/tools/opensnoop.py
|
||||
[2]:https://github.com/iovisor/bcc/blob/master/tools/tcplife.py
|
||||
[3]:https://github.com/iovisor/bcc/blob/master/tools/cpudist.py
|
||||
[4]:https://github.com/jvns/rust-bcc
|
||||
[5]:https://crates.io/crates/bcc
|
||||
[6]:https://github.com/iovisor/bcc
|
||||
[7]:https://github.com/iovisor/bcc/tree/master/tools
|
||||
[8]:https://github.com/iovisor/ply
|
||||
[9]:https://github.com/iovisor/bcc/blob/master/examples/tracing/strlen_count.py
|
||||
[10]:https://github.com/iovisor/bcc/blob/master/docs/reference_guide.md#maps
|
||||
[11]:https://github.com/iovisor/gobpf
|
||||
[12]:https://github.com/jvns/rust-bcc/blob/f15d2983ddbe349aac3d2fcaeacf924a66db4be7/examples/strlen.rs
|
||||
[13]:https://github.com/jvns/rust-bcc/blob/f15d2983ddbe349aac3d2fcaeacf924a66db4be7/examples/opensnoop.rs
|
||||
[14]:https://github.com/jvns/rust-bcc/blob/f15d2983ddbe349aac3d2fcaeacf924a66db4be7/examples/opensnoop.c
|
||||
[15]:https://github.com/iovisor/bcc/blob/master/tools/opensnoop.py
|
||||
[16]:https://github.com/jvns/ruby-mem-watcher-demo/blob/dd189b178a2813e6445063f0f84063e6e978ee79/src/bin/count-ruby-allocs.rs
|
||||
[17]:https://unhandledexpression.com/2018/02/02/poc-compiling-to-ebpf-from-rust/
|
||||
[18]:https://bitbucket.org/photoszzt/rust-bpf/
|
||||
[19]:https://github.com/jvns/rust-bcc
|
||||
@ -0,0 +1,166 @@
|
||||
Token ERC Comparison for Fungible Tokens – Blockchainers
|
||||
======
|
||||
“The good thing about standards is that there are so many to choose from.” [_Andrew S. Tanenbaum_][1]
|
||||
|
||||
### Current State of Token Standards
|
||||
|
||||
The current state of Token standards on the Ethereum platform is surprisingly simple: ERC-20 Token Standard is the only accepted and adopted (as [EIP-20][2]) standard for a Token interface.
|
||||
|
||||
Proposed in 2015, it has finally been accepted at the end of 2017.
|
||||
|
||||
In the meantime, many Ethereum Requests for Comments (ERC) have been proposed which address shortcomings of the ERC-20, which partly were caused by changes in the Ethereum platform itself, eg. the fix for the re-entrancy bug with [EIP-150][3]. Other ERC propose enhancements to the ERC-20 Token model. These enhancements were identified by experiences gathered due to the broad adoption of the Ethereum blockchain and the ERC-20 Token standard. The actual usage of the ERC-20 Token interface resulted in new demands and requirements to address non-functional requirements like permissioning and operations.
|
||||
|
||||
This blogpost should give a superficial, but complete, overview of all proposals for Token(-like) standards on the Ethereum platform. This comparison tries to be objective but most certainly will fail in doing so.
|
||||
|
||||
### The Mother of all Token Standards: ERC-20
|
||||
|
||||
There are dozens of [very good][4] and detailed description of the ERC-20, which will not be repeated here. Just the core concepts relevant for comparing the proposals are mentioned in this post.
|
||||
|
||||
#### The Withdraw Pattern
|
||||
|
||||
Users trying to understand the ERC-20 interface and especially the usage pattern for _transfer_ ing Tokens _from_ one externally owned account (EOA), ie. an end-user (“Alice”), to a smart contract, have a hard time getting the approve/transferFrom pattern right.
|
||||
|
||||
![][5]
|
||||
|
||||
From a software engineering perspective, this withdraw pattern is very similar to the [Hollywood principle][6] (“Don’t call us, we’ll call you!”). The idea is that the call chain is reversed: during the ERC-20 Token transfer, the Token doesn’t call the contract, but the contract does the call transferFrom on the Token.
|
||||
|
||||
While the Hollywood Principle is often used to implement Separation-of-Concerns (SoC), in Ethereum it is a security pattern to avoid having the Token contract to call an unknown function on an external contract. This behaviour was necessary due to the [Call Depth Attack][7] until [EIP-150][3] was activated. After this hard fork, the re-entrancy bug was not possible anymore and the withdraw pattern did not provide any more security than calling the Token directly.
|
||||
|
||||
But why should it be a problem now, the usage might be somehow clumsy, but we can fix this in the DApp frontend, right?
|
||||
|
||||
So, let’s see what happens if a user used transfer to send Tokens to a smart contract. Alice calls transfer on the Token contract with the contract address
|
||||
|
||||
**….aaaaand it’s gone!**
|
||||
|
||||
That’s right, the Tokens are gone. Most likely, nobody will ever get the Tokens back. But Alice is not alone, as Dexaran, inventor of ERC-223, found out, about $400.000 in tokens (let’s just say _a lot_ due to the high volatility of ETH) are irretrievably lost for all of us due to users accidentally sending Tokens to smart contracts.
|
||||
|
||||
Even if the contract developer was extremely user friendly and altruistic, he couldn’t create the contract so that it could react to getting Tokens transferred to it and eg. return them, as the contract will never be notified of this transfer and the event is only emitted on the Token contract.
|
||||
|
||||
From a software engineering perspective that’s a severe shortcoming of ERC-20. If an event occurs (and for the sake of simplicity, we are now assuming Ethereum transactions are actually events), there should be a notification to the parties involved. However, there is an event, but it’s triggered in the Token smart contract which the receiving contract cannot know.
|
||||
|
||||
Currently, it’s not possible to prevent users sending Tokens to smart contracts and losing them forever using the unintuitive transfer on the ERC-20 Token contract.
|
||||
|
||||
### The Empire Strikes Back: ERC-223
|
||||
|
||||
The first attempt at fixing the problems of ERC-20 was proposed by [Dexaran][8]. The main issue solved by this proposal is the different handling of EOA and smart contract accounts.
|
||||
|
||||
The compelling strategy is to reverse the calling chain (and with [EIP-150][3] solved this is now possible) and use a pre-defined callback (tokenFallback) on the receiving smart contract. If this callback is not implemented, the transfer will fail (costing all gas for the sender, a common criticism for ERC-223).
|
||||
|
||||
![][9]
|
||||
|
||||
#### Pros:
|
||||
|
||||
* Establishes a new interface, intentionally being not compliant to ERC-20 with respect to the deprecated functions
|
||||
|
||||
* Allows contract developers to handle incoming tokens (eg. accept/reject) since event pattern is followed
|
||||
|
||||
* Uses one transaction instead of two (transfer vs. approve/transferFrom) and thus saves gas and Blockchain storage
|
||||
|
||||
|
||||
|
||||
|
||||
#### Cons:
|
||||
|
||||
* If tokenFallback doesn’t exist then the contract fallback function is executed, this might have unintended side-effects
|
||||
|
||||
* If contracts assume that transfer works with Tokens, eg. for sending Tokens to specific contracts like multi-sig wallets, this would fail with ERC-223 Tokens, making it impossible to move them (ie. they are lost)
|
||||
|
||||
|
||||
### The Pragmatic Programmer: ERC-677
|
||||
|
||||
The [ERC-667 transferAndCall Token Standard][10] tries to marriage the ERC-20 and ERC-223. The idea is to introduce a transferAndCall function to the ERC-20, but keep the standard as is. ERC-223 intentionally is not completely backwards compatible, since the approve/allowance pattern is not needed anymore and was therefore removed.
|
||||
|
||||
The main goal of ERC-667 is backward compatibility, providing a safe way for new contracts to transfer tokens to external contracts.
|
||||
|
||||
![][11]
|
||||
|
||||
#### Pros:
|
||||
|
||||
* Easy to adapt for new Tokens
|
||||
|
||||
* Compatible to ERC-20
|
||||
|
||||
* Adapter for ERC-20 to use ERC-20 safely
|
||||
|
||||
#### Cons:
|
||||
|
||||
* No real innovations. A compromise of ERC-20 and ERC-223
|
||||
|
||||
* Current implementation [is not finished][12]
|
||||
|
||||
|
||||
### The Reunion: ERC-777
|
||||
|
||||
[ERC-777 A New Advanced Token Standard][13] was introduced to establish an evolved Token standard which learned from misconceptions like approve() with a value and the aforementioned send-tokens-to-contract-issue.
|
||||
|
||||
Additionally, the ERC-777 uses the new standard [ERC-820: Pseudo-introspection using a registry contract][14] which allows for registering meta-data for contracts to provide a simple type of introspection. This allows for backwards compatibility and other functionality extensions, depending on the ITokenRecipient returned by a EIP-820 lookup on the to address, and the functions implemented by the target contract.
|
||||
|
||||
ERC-777 adds a lot of learnings from using ERC-20 Tokens, eg. white-listed operators, providing Ether-compliant interfaces with send(…), using the ERC-820 to override and adapt functionality for backwards compatibility.
|
||||
|
||||
![][15]
|
||||
|
||||
#### Pros:
|
||||
|
||||
* Well thought and evolved interface for tokens, learnings from ERC-20 usage
|
||||
|
||||
* Uses the new standard request ERC-820 for introspection, allowing for added functionality
|
||||
|
||||
* White-listed operators are very useful and are more necessary than approve/allowance , which was often left infinite
|
||||
|
||||
|
||||
#### Cons:
|
||||
|
||||
* Is just starting, complex construction with dependent contract calls
|
||||
|
||||
* Dependencies raise the probability of security issues: first security issues have been [identified (and solved)][16] not in the ERC-777, but in the even newer ERC-820
|
||||
|
||||
|
||||
|
||||
|
||||
### (Pure Subjective) Conclusion
|
||||
|
||||
For now, if you want to go with the “industry standard” you have to choose ERC-20. It is widely supported and well understood. However, it has its flaws, the biggest one being the risk of non-professional users actually losing money due to design and specification issues. ERC-223 is a very good and theoretically founded answer for the issues in ERC-20 and should be considered a good alternative standard. Implementing both interfaces in a new token is not complicated and allows for reduced gas usage.
|
||||
|
||||
A pragmatic solution to the event and money loss problem is ERC-677, however it doesn’t offer enough innovation to establish itself as a standard. It could however be a good candidate for an ERC-20 2.0.
|
||||
|
||||
ERC-777 is an advanced token standard which should be the legitimate successor to ERC-20, it offers great concepts which are needed on the matured Ethereum platform, like white-listed operators, and allows for extension in an elegant way. Due to its complexity and dependency on other new standards, it will take time till the first ERC-777 tokens will be on the Mainnet.
|
||||
|
||||
### Links
|
||||
|
||||
[1] Security Issues with approve/transferFrom-Pattern in ERC-20: <https://drive.google.com/file/d/0ByMtMw2hul0EN3NCaVFHSFdxRzA/view>
|
||||
|
||||
[2] No Event Handling in ERC-20: <https://docs.google.com/document/d/1Feh5sP6oQL1-1NHi-X1dbgT3ch2WdhbXRevDN681Jv4>
|
||||
|
||||
[3] Statement for ERC-20 failures and history: <https://github.com/ethereum/EIPs/issues/223#issuecomment-317979258>
|
||||
|
||||
[4] List of differences ERC-20/223: <https://ethereum.stackexchange.com/questions/17054/erc20-vs-erc223-list-of-differences>
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://blockchainers.org/index.php/2018/02/08/token-erc-comparison-for-fungible-tokens/
|
||||
|
||||
作者：[Alexander Culum][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://blockchainers.org/index.php/author/alex/
|
||||
[1]:https://www.goodreads.com/quotes/589703-the-good-thing-about-standards-is-that-there-are-so
|
||||
[2]:https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md
|
||||
[3]:https://github.com/ethereum/EIPs/blob/master/EIPS/eip-150.md
|
||||
[4]:https://medium.com/@jgm.orinoco/understanding-erc-20-token-contracts-a809a7310aa5
|
||||
[5]:http://blockchainers.org/wp-content/uploads/2018/02/ERC-20-Token-Transfer-2.png
|
||||
[6]:http://matthewtmead.com/blog/hollywood-principle-dont-call-us-well-call-you-4/
|
||||
[7]:https://consensys.github.io/smart-contract-best-practices/known_attacks/
|
||||
[8]:https://github.com/Dexaran
|
||||
[9]:http://blockchainers.org/wp-content/uploads/2018/02/ERC-223-Token-Transfer-1.png
|
||||
[10]:https://github.com/ethereum/EIPs/issues/677
|
||||
[11]:http://blockchainers.org/wp-content/uploads/2018/02/ERC-677-Token-Transfer.png
|
||||
[12]:https://github.com/ethereum/EIPs/issues/677#issuecomment-353871138
|
||||
[13]:https://github.com/ethereum/EIPs/issues/777
|
||||
[14]:https://github.com/ethereum/EIPs/issues/820
|
||||
[15]:http://blockchainers.org/wp-content/uploads/2018/02/ERC-777-Token-Transfer.png
|
||||
[16]:https://github.com/ethereum/EIPs/issues/820#issuecomment-362049573
|
||||
72
sources/tech/20180301 Best Websites For Programmers.md
Normal file
72
sources/tech/20180301 Best Websites For Programmers.md
Normal file
@ -0,0 +1,72 @@
|
||||
Best Websites For Programmers
|
||||
======
|
||||
![][1]
|
||||
|
||||
As a programmer, you will often find yourself as a permanent visitor of some websites. These can be tutorial, reference or forums websites. So here in this article let us have a look at the best websites for programmers.
|
||||
|
||||
### W3Schools
|
||||
W3Schools is one of the best websites for beginners as well as experienced web developers to learn various programming languages. You can learn HTML5, CSS3, PHP. JavaScript, ASP etc.
|
||||
|
||||
More importantly, the website holds a lot of resources and references for web developers.
|
||||
|
||||
[![w3schools logo][2]][3]
|
||||
|
||||
You can quickly see various keywords and what they do. The website is very interactive and it allows you to try and practice the code in an embedded editor on the website itself. The website is one of those few that you will frequently visit as a web developer.
|
||||
|
||||
### GeeksforGeeks
|
||||
GeeksforGeeks is a website mostly focused on computer science. It has a huge collection of algorithms, solutions and programming questions.
|
||||
|
||||
[![geeksforgeeks programming support][4]][5]
|
||||
|
||||
The website also has a good stock of most frequently asked questions in interviews. Since the website is more about computer science in general, you will find a solution to all programming solutions in most famous languages.
|
||||
|
||||
### TutorialsPoint
|
||||
The de facto place for learning anything. Tutorials point has some of the finest and easiest tutorials that can teach you any programming language. What I really love about this website is that it is not just limited to generic programming languages.
|
||||
|
||||
|
||||
|
||||
You can find tutorials for almost all frameworks of all languages on the planet.
|
||||
|
||||
### StackOverflow
|
||||
You probably already know this that stack is the place where programmers meet. You ever get stuck solving some of your code, just ask a question on stack and programmers from all over the internet will be there to help you.
|
||||
|
||||
[![stackoverflow linux programming website][6]][7]
|
||||
|
||||
The best part about stack overflow is that almost all questions get answered. You might as well receive answers from several different points of views of other programmers.
|
||||
|
||||
### HackerRank
|
||||
Hacker rank is a website where you can participate in various coding competitions and check your competitive abilities.
|
||||
|
||||
[![hackerrank programming forums][8]][9]There are various contests organized in various programming languages and winning in them increases your score. This score can get you in the top ranks and increase your chance of getting noticed by some software company.
|
||||
|
||||
### Codebeautify
|
||||
Since we are programmers, beauty isn’t something we look after. Many a time our code can be difficult to read by someone else. Codebeautify can make your code easy to read.
|
||||
|
||||
|
||||
|
||||
The website has most languages that it can beautify. Alternatively, if you wish to make your code not readable by someone you can also do that.
|
||||
|
||||
So these were some of my picks for the best websites for programmers. If you frequently visit a site that I haven’t mentioned, do let me know in the comment section below.
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://www.theitstuff.com/best-websites-programmers
|
||||
|
||||
作者：[Rishabh Kandari][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://www.theitstuff.com/author/reevkandari
|
||||
[1]:http://www.theitstuff.com/wp-content/uploads/2017/12/best-websites-for-programmers.jpg
|
||||
[2]:http://www.theitstuff.com/wp-content/uploads/2017/12/w3schools-logo-550x110.png
|
||||
[3]:http://www.theitstuff.com/wp-content/uploads/2017/12/w3schools-logo.png
|
||||
[4]:http://www.theitstuff.com/wp-content/uploads/2017/12/geeksforgeeks-programming-support-550x152.png
|
||||
[5]:http://www.theitstuff.com/wp-content/uploads/2017/12/geeksforgeeks-programming-support.png
|
||||
[6]:http://www.theitstuff.com/wp-content/uploads/2017/12/stackoverflow-linux-programming-website-550x178.png
|
||||
[7]:http://www.theitstuff.com/wp-content/uploads/2017/12/stackoverflow-linux-programming-website.png
|
||||
[8]:http://www.theitstuff.com/wp-content/uploads/2017/12/hackerrank-programming-forums-550x118.png
|
||||
[9]:http://www.theitstuff.com/wp-content/uploads/2017/12/hackerrank-programming-forums.png
|
||||
@ -1,157 +0,0 @@
|
||||
Translating by qhwdw
|
||||
Top 9 open source ERP systems to consider | Opensource.com
|
||||
======
|
||||
|
||||
Businesses with more than a handful of employees have a lot to balance including pricing, product planning, accounting and finance, managing payroll, dealing with inventory, and more. Stitching together a set of disparate tools to handle those jobs is a quick, cheap, and dirty way to get things done.
|
||||
|
||||
That approach isn't scalable. It's difficult to efficiently move data between the various pieces of such an ad-hoc system. As well, it can be difficult to maintain.
|
||||
|
||||
Instead, most growing businesses turn to an [enterprise resource planning][1] (ERP) system.
|
||||
|
||||
The big guns in that space are Oracle, SAP, and Microsoft Dynamics. Their offerings are comprehensive, but also expensive. What happens if your business can't afford one of those big implementations or if your needs are simple? You turn to the open source alternatives.
|
||||
|
||||
### What to look for in an ERP system
|
||||
|
||||
Obviously, you want a system that suits your needs. Depending on those needs, more features doesn't always mean better. However, your needs might change as your business grows, so you'll want to find an ERP system that can expand to meet your new needs. That could mean the system has additional modules or just supports plugins and add-ons.
|
||||
|
||||
Most open source ERP systems are web applications. You can download and install them on your server. But if you don't want (or don't have the skills or staff) to maintain a system yourself, then make sure there's a hosted version of the application available.
|
||||
|
||||
Finally, you'll want to make sure the application has good documentation and good support—either in the form of paid support or an active user community.
|
||||
|
||||
There are a number of flexible, feature-rich, and cost-effective open source ERP systems out there. Here are nine to check out if you're in the market for such a system.
|
||||
|
||||
### ADempiere
|
||||
|
||||
Like most other open source ERP solutions, [ADempiere][2] is targeted at small and midsized businesses. It's been around awhile—the project was formed in 2006 as a fork from the Compiere ERP software.
|
||||
|
||||
Its Italian name means to achieve or satisfy, and its "multidimensional" ERP features aim to help businesses satisfy a wide range of needs. It adds supply chain management (SCM) and customer relationship management (CRM) features to its ERP suite to help manage sales, purchasing, inventory, and accounting processes in one piece of software. Its latest release, v.3.9.0, updated its user interface, point-of-sale, HR, payroll, and other features.
|
||||
|
||||
As a multiplatform, Java-based cloud solution, ADempiere is accessible on Linux, Unix, Windows, MacOS, smartphones, and tablets. It is licensed under [GPLv2][3]. If you'd like to learn more, take its [demo][4] for a test run or access its [source code][5] on GitHub.
|
||||
|
||||
### Apache OFBiz
|
||||
|
||||
[Apache OFBiz][6]'s suite of related business tools is built on a common architecture that enables organizations to customize the ERP to their needs. As a result, it's best suited for midsize or large enterprises that have the internal development resources to adapt and integrate it within their existing IT and business processes.
|
||||
|
||||
OFBiz is a mature open source ERP system; its website says it's been a top-level Apache project for a decade. [Modules][7] are available for accounting, manufacturing, HR, inventory management, catalog management, CRM, and e-commerce. You can also try out its e-commerce web store and backend ERP applications on its [demo page][8].
|
||||
|
||||
Apache OFBiz's source code can be found in the [project's repository][9]. It is written in Java and licensed under an [Apache 2.0 license][10].
|
||||
|
||||
### Dolibarr
|
||||
|
||||
[Dolibarr][11] offers end-to-end management for small and midsize businesses—from keeping track of invoices, contracts, inventory, orders, and payments to managing documents and supporting electronic point-of-sale system. It's all wrapped in a fairly clean interface.
|
||||
|
||||
If you're wondering what Dolibarr can't do, [here's some documentation about that][12].
|
||||
|
||||
In addition to an [online demo][13], Dolibarr also has an [add-ons store][14] where you can buy software that extends its features. You can check out its [source code][15] on GitHub; it's licensed under [GPLv3][16] or any later version.
|
||||
|
||||
### ERPNext
|
||||
|
||||
[ERPNext][17] is one of those classic open source projects; in fact, it was [featured on Opensource.com][18] way back in 2014. It was designed to scratch a particular itch, in this case replacing a creaky and expensive proprietary ERP implementation.
|
||||
|
||||
ERPNext was built for small and midsized businesses. It includes modules for accounting, managing inventory, sales, purchase, and project management. The applications that make up ERPNext are form-driven—you fill information in a set of fields and let the application do the rest. The whole suite is easy to use.
|
||||
|
||||
If you're interested, you can request a [demo][19] before taking the plunge and [downloading it][20] or [buying a subscription][21] to the hosted service.
|
||||
|
||||
### Metasfresh
|
||||
|
||||
[Metasfresh][22]'s name reflects its commitment to keeping its code "fresh." It's released weekly updates since late 2015, when its founders forked the code from the ADempiere project. Like ADempiere, it's an open source ERP based on Java targeted at the small and midsize business market.
|
||||
|
||||
While it's a younger project than most of the other software described here, it's attracted some early, positive attention, such as being named a finalist for the Initiative Mittelstand "best of open source" IT innovation award.
|
||||
|
||||
Metasfresh is free when self-hosted or for one user via the cloud, or on a monthly subscription fee basis as a cloud-hosted solution for 1-100 users. Its [source code][23] is available under the [GPLv2][24] license at GitHub and its cloud version is licensed under GPLv3.
|
||||
|
||||
### Odoo
|
||||
|
||||
[Odoo][25] is an integrated suite of applications that includes modules for project management, billing, accounting, inventory management, manufacturing, and purchasing. Those modules can communicate with each other to efficiently and seamlessly exchange information.
|
||||
|
||||
While ERP can be complex, Odoo makes it friendlier with a simple, almost spartan interface. The interface is reminiscent of Google Drive, with just the functions you need visible. You can [give Odoo a try][26] before you decide to sign up.
|
||||
|
||||
Odoo is a web-based tool. Subscriptions to individual modules will set you back $20 (USD) a month for each one. You can also [download it][27] or grab the [source code][28] from GitHub. It's licensed under [LGPLv3][29].
|
||||
|
||||
### Opentaps
|
||||
|
||||
[Opentaps][30], one of the few open source ERP solutions designed for larger businesses, packs a lot of power and flexibility. This is no surprise because it's built on top of Apache OFBiz.
|
||||
|
||||
You get the expected set of modules that help you manage inventory, manufacturing, financials, and purchasing. You also get an analytics feature that helps you analyze all aspects of your business. You can use that information to better plan into the future. Opentaps also packs a powerful reporting function.
|
||||
|
||||
On top of that, you can [buy add-ons and additional modules][31] to enhance Opentaps' capabilities. They include integration with Amazon Marketplace Services and FedEx. Before you [download Opentaps][32], give the [online demo][33] a try. It's licensed under [GPLv3][34].
|
||||
|
||||
### WebERP
|
||||
|
||||
[WebERP][35] is exactly as it sounds: An ERP system that operates through a web browser. The only other software you need is a PDF reader to view reports.
|
||||
|
||||
Specifically, its an accounting and business management solution geared toward wholesale, distribution, and manufacturing businesses. It also integrates with [third-party business software][36], including a point-of-sale system for multi-branch retail management, an e-commerce module, and wiki software for building a business knowledge base. It's written in PHP and aims to be a low-footprint, efficient, fast, and platform-independent system that's easy for general business users.
|
||||
|
||||
WebERP is actively being developed and has an active [forum][37], where you can ask questions or learn more about using the application. You can also try a [demo][38] or download the [source code][39] (licensed under [GPLv2][40]) on GitHub.
|
||||
|
||||
### xTuple PostBooks
|
||||
|
||||
If your manufacturing, distribution, or e-commerce business has outgrown its small business roots and is looking for an ERP to grow with you, you may want to check out [xTuple PostBooks][41]. It's a comprehensive solution built around its core ERP, accounting, and CRM features that adds inventory, distribution, purchasing, and vendor reporting capabilities.
|
||||
|
||||
xTuple is available under the Common Public Attribution License ([CPAL][42]), and the project welcomes developers to fork it to create other business software for inventory-based manufacturers. Its web app core is written in JavaScript, and its [source code][43] can be found on GitHub. To see if it's right for you, register for a free [demo][44] on xTuple's website.
|
||||
|
||||
There are many other open source ERP options you can choose from—others you might want to check out include [Tryton][45], which is written in Python and uses the PostgreSQL database engine, or the Java-based [Axelor][46], which touts users' ability to create or modify business apps with a drag-and-drop interface. And, if your favorite open source ERP solution isn't on the list, please share it with us in the comments. You might also check out our list of top [supply chain management tools][47].
|
||||
|
||||
This article is updated from a [previous version][48] authored by Opensource.com moderator [Scott Nesbitt][49].
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/tools/enterprise-resource-planning
|
||||
|
||||
作者：[Opensource.com][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://opensource.com
|
||||
[1]:http://en.wikipedia.org/wiki/Enterprise_resource_planning
|
||||
[2]:http://www.adempiere.net/welcome
|
||||
[3]:http://wiki.adempiere.net/License
|
||||
[4]:http://www.adempiere.net/web/guest/demo
|
||||
[5]:https://github.com/adempiere/adempiere
|
||||
[6]:http://ofbiz.apache.org/
|
||||
[7]:https://ofbiz.apache.org/business-users.html#UsrModules
|
||||
[8]:http://ofbiz.apache.org/ofbiz-demos.html
|
||||
[9]:http://ofbiz.apache.org/source-repositories.html
|
||||
[10]:http://www.apache.org/licenses/LICENSE-2.0
|
||||
[11]:http://www.dolibarr.org/
|
||||
[12]:http://wiki.dolibarr.org/index.php/What_Dolibarr_can%27t_do
|
||||
[13]:http://www.dolibarr.org/onlinedemo
|
||||
[14]:http://www.dolistore.com/
|
||||
[15]:https://github.com/Dolibarr/dolibarr
|
||||
[16]:https://github.com/Dolibarr/dolibarr/blob/develop/COPYING
|
||||
[17]:https://erpnext.com/
|
||||
[18]:https://opensource.com/business/14/11/building-open-source-erp
|
||||
[19]:https://frappe.erpnext.com/request-a-demo
|
||||
[20]:https://erpnext.com/download
|
||||
[21]:https://erpnext.com/pricing
|
||||
[22]:http://metasfresh.com/en/
|
||||
[23]:https://github.com/metasfresh/metasfresh
|
||||
[24]:https://github.com/metasfresh/metasfresh/blob/master/LICENSE.md
|
||||
[25]:https://www.odoo.com/
|
||||
[26]:https://www.odoo.com/page/start
|
||||
[27]:https://www.odoo.com/page/download
|
||||
[28]:https://github.com/odoo
|
||||
[29]:https://github.com/odoo/odoo/blob/11.0/LICENSE
|
||||
[30]:http://www.opentaps.org/
|
||||
[31]:http://shop.opentaps.org/
|
||||
[32]:http://www.opentaps.org/products/download
|
||||
[33]:http://www.opentaps.org/products/online-demo
|
||||
[34]:https://www.gnu.org/licenses/agpl-3.0.html
|
||||
[35]:http://www.weberp.org/
|
||||
[36]:http://www.weberp.org/Links.html
|
||||
[37]:http://www.weberp.org/forum/
|
||||
[38]:http://www.weberp.org/weberp/
|
||||
[39]:https://github.com/webERP-team/webERP
|
||||
[40]:https://github.com/webERP-team/webERP#legal
|
||||
[41]:https://xtuple.com/
|
||||
[42]:https://xtuple.com/products/license-options#cpal
|
||||
[43]:http://xtuple.github.io/
|
||||
[44]:https://xtuple.com/free-demo
|
||||
[45]:http://www.tryton.org/
|
||||
[46]:https://www.axelor.com/
|
||||
[47]:https://opensource.com/tools/supply-chain-management
|
||||
[48]:https://opensource.com/article/16/3/top-4-open-source-erp-systems
|
||||
[49]:https://opensource.com/users/scottnesbitt
|
||||
@ -1,3 +1,4 @@
|
||||
translating by wyxplus
|
||||
Things You Should Know About Ubuntu 18.04
|
||||
======
|
||||
[Ubuntu 18.04 release][1] is just around the corner. I can see lots of questions from Ubuntu users in various Facebook groups and forums. I also organized Q&A sessions on Facebook and Instagram to know what Ubuntu users are wondering about Ubuntu 18.04.
|
||||
|
||||
@ -0,0 +1,194 @@
|
||||
How to get a core dump for a segfault on Linux
|
||||
============================================================
|
||||
|
||||
This week at work I spent all week trying to debug a segfault. I’d never done this before, and some of the basic things involved (get a core dump! find the line number that segfaulted!) took me a long time to figure out. So here’s a blog post explaining how to do those things!
|
||||
|
||||
At the end of this blog post, you should know how to go from “oh no my program is segfaulting and I have no idea what is happening” to “well I know what its stack / line number was when it segfaulted at at least!“.
|
||||
|
||||
### what’s a segfault?
|
||||
|
||||
A “segmentation fault” is when your program tries to access memory that it’s not allowed to access, or tries to . This can be caused by:
|
||||
|
||||
* trying to dereference a null pointer (you’re not allowed to access the memory address `0`)
|
||||
|
||||
* trying to dereference some other pointer that isn’t in your memory
|
||||
|
||||
* a C++ vtable pointer that got corrupted and is pointing to the wrong place, which causes the program to try to execute some memory that isn’t executable
|
||||
|
||||
* some other things that I don’t understand, like I think misaligned memory accesses can also segfault
|
||||
|
||||
This “C++ vtable pointer” thing is what was happening to my segfaulting program. I might explain that in a future blog post because I didn’t know any C++ at the beginning of this week and this vtable lookup thing was a new way for a program to segfault that I didn’t know about.
|
||||
|
||||
But! This blog post isn’t about C++ bugs. Let’s talk about the basics, like, how do we even get a core dump?
|
||||
|
||||
### step 1: run valgrind
|
||||
|
||||
I found the easiest way to figure out why my program is segfaulting was to use valgrind: I ran
|
||||
|
||||
```
|
||||
valgrind -v your-program
|
||||
|
||||
```
|
||||
|
||||
and this gave me a stack trace of what happened. Neat!
|
||||
|
||||
But I wanted also wanted to do a more in-depth investigation and find out more than just what valgrind was telling me! So I wanted to get a core dump and explore it.
|
||||
|
||||
### How to get a core dump
|
||||
|
||||
A core dump is a copy of your program’s memory, and it’s useful when you’re trying to debug what went wrong with your problematic program.
|
||||
|
||||
When your program segfaults, the Linux kernel will sometimes write a core dump to disk. When I originally tried to get a core dump, I was pretty frustrated for a long time because – Linux wasn’t writing a core dump!! Where was my core dump????
|
||||
|
||||
Here’s what I ended up doing:
|
||||
|
||||
1. Run `ulimit -c unlimited` before starting my program
|
||||
|
||||
2. Run `sudo sysctl -w kernel.core_pattern=/tmp/core-%e.%p.%h.%t`
|
||||
|
||||
### ulimit: set the max size of a core dump
|
||||
|
||||
`ulimit -c` sets the maximum size of a core dump. It’s often set to 0, which means that the kernel won’t write core dumps at all. It’s in kilobytes. ulimits are per process – you can see a process’s limits by running `cat /proc/PID/limit`
|
||||
|
||||
For example these are the limits for a random Firefox process on my system:
|
||||
|
||||
```
|
||||
$ cat /proc/6309/limits
|
||||
Limit Soft Limit Hard Limit Units
|
||||
Max cpu time unlimited unlimited seconds
|
||||
Max file size unlimited unlimited bytes
|
||||
Max data size unlimited unlimited bytes
|
||||
Max stack size 8388608 unlimited bytes
|
||||
Max core file size 0 unlimited bytes
|
||||
Max resident set unlimited unlimited bytes
|
||||
Max processes 30571 30571 processes
|
||||
Max open files 1024 1048576 files
|
||||
Max locked memory 65536 65536 bytes
|
||||
Max address space unlimited unlimited bytes
|
||||
Max file locks unlimited unlimited locks
|
||||
Max pending signals 30571 30571 signals
|
||||
Max msgqueue size 819200 819200 bytes
|
||||
Max nice priority 0 0
|
||||
Max realtime priority 0 0
|
||||
Max realtime timeout unlimited unlimited us
|
||||
|
||||
```
|
||||
|
||||
The kernel uses the soft limit (in this case, “max core file size = 0”) when deciding how big of a core file to write. You can increase the soft limit up to the hard limit using the `ulimit` shell builtin (`ulimit -c unlimited`!)
|
||||
|
||||
### kernel.core_pattern: where core dumps are written
|
||||
|
||||
`kernel.core_pattern` is a kernel parameter or a “sysctl setting” that controls where the Linux kernel writes core dumps to disk.
|
||||
|
||||
Kernel parameters are a way to set global settings on your system. You can get a list of every kernel parameter by running `sysctl -a`, or use `sysctl kernel.core_pattern` to look at the `kernel.core_pattern` setting specifically.
|
||||
|
||||
So `sysctl -w kernel.core_pattern=/tmp/core-%e.%p.%h.%t` will write core dumps to `/tmp/core-<a bunch of stuff identifying the process>`
|
||||
|
||||
If you want to know more about what these `%e`, `%p` parameters read, see [man core][1].
|
||||
|
||||
It’s important to know that `kernel.core_pattern` is a global settings – it’s good to be a little careful about changing it because it’s possible that other systems depend on it being set a certain way.
|
||||
|
||||
### kernel.core_pattern & Ubuntu
|
||||
|
||||
By default on Ubuntu systems, this is what `kernel.core_pattern` is set to
|
||||
|
||||
```
|
||||
$ sysctl kernel.core_pattern
|
||||
kernel.core_pattern = |/usr/share/apport/apport %p %s %c %d %P
|
||||
|
||||
```
|
||||
|
||||
This caused me a lot of confusion (what is this apport thing and what is it doing with my core dumps??) so here’s what I learned about this:
|
||||
|
||||
* Ubuntu uses a system called “apport” to report crashes in apt packages
|
||||
|
||||
* Setting `kernel.core_pattern=|/usr/share/apport/apport %p %s %c %d %P`means that core dumps will be piped to `apport`
|
||||
|
||||
* apport has logs in /var/log/apport.log
|
||||
|
||||
* apport by default will ignore crashes from binaries that aren’t part of an Ubuntu packages
|
||||
|
||||
I ended up just overriding this Apport business and setting `kernel.core_pattern` to `sysctl -w kernel.core_pattern=/tmp/core-%e.%p.%h.%t` because I was on a dev machine, I didn’t care whether Apport was working on not, and I didn’t feel like trying to convince Apport to give me my core dumps.
|
||||
|
||||
### So you have a core dump. Now what?
|
||||
|
||||
Okay, now we know about ulimits and `kernel.core_pattern` and you have actually have a core dump file on disk in `/tmp`. Amazing! Now what??? We still don’t know why the program segfaulted!
|
||||
|
||||
The next step is to open the core file with `gdb` and get a backtrace.
|
||||
|
||||
### Getting a backtrace from gdb
|
||||
|
||||
You can open a core file with gdb like this:
|
||||
|
||||
```
|
||||
$ gdb -c my_core_file
|
||||
|
||||
```
|
||||
|
||||
Next, we want to know what the stack was when the program crashed. Running `bt` at the gdb prompt will give you a backtrace. In my case gdb hadn’t loaded symbols for the binary, so it was just like `??????`. Luckily, loading symbols fixed it.
|
||||
|
||||
Here’s how to load debugging symbols.
|
||||
|
||||
```
|
||||
symbol-file /path/to/my/binary
|
||||
sharedlibrary
|
||||
|
||||
```
|
||||
|
||||
This loads symbols from the binary and from any shared libraries the binary uses. Once I did that, gdb gave me a beautiful stack trace with line numbers when I ran `bt`!!!
|
||||
|
||||
If you want this to work, the binary should be compiled with debugging symbols. Having line numbers in your stack traces is extremely helpful when trying to figure out why a program crashed :)
|
||||
|
||||
### look at the stack for every thread
|
||||
|
||||
Here’s how to get the stack for every thread in gdb!
|
||||
|
||||
```
|
||||
thread apply all bt full
|
||||
|
||||
```
|
||||
|
||||
### gdb + core dumps = amazing
|
||||
|
||||
If you have a core dump & debugging symbols and gdb, you are in an amazing situation!! You can go up and down the call stack, print out variables, and poke around in memory to see what happened. It’s the best.
|
||||
|
||||
If you are still working on being a gdb wizard, you can also just print out the stack trace with `bt` and that’s okay :)
|
||||
|
||||
### ASAN
|
||||
|
||||
Another path to figuring out your segfault is to do one compile the program with AddressSanitizer (“ASAN”) (`$CC -fsanitize=address`) and run it. I’m not going to discuss that in this post because this is already pretty long and anyway in my case the segfault disappeared with ASAN turned on for some reason, possibly because the ASAN build used a different memory allocator (system malloc instead of tcmalloc).
|
||||
|
||||
I might write about ASAN more in the future if I ever get it to work :)
|
||||
|
||||
### getting a stack trace from a core dump is pretty approachable!
|
||||
|
||||
This blog post sounds like a lot and I was pretty confused when I was doing it but really there aren’t all that many steps to getting a stack trace out of a segfaulting program:
|
||||
|
||||
1. try valgrind
|
||||
|
||||
if that doesn’t work, or if you want to have a core dump to investigate:
|
||||
|
||||
1. make sure the binary is compiled with debugging symbols
|
||||
|
||||
2. set `ulimit` and `kernel.core_pattern` correctly
|
||||
|
||||
3. run the program
|
||||
|
||||
4. open your core dump with `gdb`, load the symbols, and run `bt`
|
||||
|
||||
5. try to figure out what happened!!
|
||||
|
||||
I was able using gdb to figure out that there was a C++ vtable entry that is pointing to some corrupt memory, which was somewhat helpful and helped me feel like I understood C++ a bit better. Maybe we’ll talk more about how to use gdb to figure things out another day!
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://jvns.ca/blog/2018/04/28/debugging-a-segfault-on-linux/
|
||||
|
||||
作者：[Julia Evans ][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://jvns.ca/about/
|
||||
[1]:http://man7.org/linux/man-pages/man5/core.5.html
|
||||
@ -1,231 +0,0 @@
|
||||
KevinSJ Translating
|
||||
A Beginners Guide To Cron Jobs
|
||||
======
|
||||
|
||||
|
||||
**Cron** is one of the most useful utility that you can find in any Unix-like operating system. It is used to schedule commands at a specific time. These scheduled commands or tasks are known as “Cron Jobs”. Cron is generally used for running scheduled backups, monitoring disk space, deleting files (for example log files) periodically which are no longer required, running system maintenance tasks and a lot more. In this brief guide, we will see the basic usage of Cron Jobs in Linux.
|
||||
|
||||
### The Beginners Guide To Cron Jobs
|
||||
|
||||
The typical format of a cron job is:
|
||||
```
|
||||
Minute(0-59) Hour(0-24) Day_of_month(1-31) Month(1-12) Day_of_week(0-6) Command_to_execute
|
||||
|
||||
```
|
||||
|
||||
Just memorize the cron job format or print the following illustration and keep it in your desk.
|
||||
|
||||
![][2]
|
||||
|
||||
In the above picture, the asterisks refers the specific blocks of time.
|
||||
|
||||
To display the contents of the **crontab** file of the currently logged in user:
|
||||
```
|
||||
$ crontab -l
|
||||
|
||||
```
|
||||
|
||||
To edit the current user’s cron jobs, do:
|
||||
```
|
||||
$ crontab -e
|
||||
|
||||
```
|
||||
|
||||
If it is the first time, you will be asked to editor to edit the jobs.
|
||||
```
|
||||
no crontab for sk - using an empty one
|
||||
|
||||
Select an editor. To change later, run 'select-editor'.
|
||||
1. /bin/nano <---- easiest
|
||||
2. /usr/bin/vim.basic
|
||||
3. /usr/bin/vim.tiny
|
||||
4. /bin/ed
|
||||
|
||||
Choose 1-4 [1]:
|
||||
|
||||
```
|
||||
|
||||
Choose any one that suits you. Here it is how a sample crontab file looks like.
|
||||
|
||||
![][3]
|
||||
|
||||
In this file, you need to add your cron jobs.
|
||||
|
||||
To edit the crontab of a different user, for example ostechnix, do:
|
||||
```
|
||||
$ crontab -u ostechnix -e
|
||||
|
||||
```
|
||||
|
||||
Let us see some examples.
|
||||
|
||||
To run a cron job **every minute** , the format should be like below.
|
||||
```
|
||||
* * * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
To run cron job every 5 minute, add the following in your crontab file.
|
||||
```
|
||||
*/5 * * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
To run a cron job at every quarter hour (every 15th minute), add this:
|
||||
```
|
||||
*/15 * * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
To run a cron job every hour at 30 minutes, run:
|
||||
```
|
||||
30 * * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
You can also define multiple time intervals separated by commas. For example, the following cron job will run three times every hour, at minutes 0, 5 and 10:
|
||||
```
|
||||
0,5,10 * * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
Run a cron job every half hour:
|
||||
```
|
||||
*/30 * * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
Run a job every hour:
|
||||
```
|
||||
0 * * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
Run a job every 2 hours:
|
||||
```
|
||||
0 */2 * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
Run a job every day (It will run at 00:00):
|
||||
```
|
||||
0 0 * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
Run a job every day at 3am:
|
||||
```
|
||||
0 3 * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
Run a job every sunday:
|
||||
```
|
||||
0 0 * * SUN <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
Or,
|
||||
```
|
||||
0 0 * * 0 <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
It will run at exactly at 00:00 on Sunday.
|
||||
|
||||
Run a job on every day-of-week from Monday through Friday i.e every weekday:
|
||||
```
|
||||
0 0 * * 1-5 <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
The job will start at 00:00.
|
||||
|
||||
Run a job every month:
|
||||
```
|
||||
0 0 1 * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
Run a job at 16:15 on day-of-month 1:
|
||||
```
|
||||
15 16 1 * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
Run a job at every quarter i.e on day-of-month 1 in every 3rd month:
|
||||
```
|
||||
0 0 1 */3 * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
Run a job on a specific month at a specific time:
|
||||
```
|
||||
5 0 * 4 * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
The job will start at 00:05 in April.
|
||||
|
||||
Run a job every 6 months:
|
||||
```
|
||||
0 0 1 */6 * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
This cron job will start at 00:00 on day-of-month 1 in every 6th month.
|
||||
|
||||
Run a job every year:
|
||||
```
|
||||
0 0 1 1 * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
This cron job will start at 00:00 on day-of-month 1 in January.
|
||||
|
||||
We can also use the following strings to define job.
|
||||
|
||||
@reboot Run once, at startup. @yearly Run once a year. @annually (same as @yearly). @monthly Run once a month. @weekly Run once a week. @daily Run once a day. @midnight (same as @daily). @hourly Run once an hour.
|
||||
|
||||
For example, to run a job every time the server is rebooted, add this line in your crontab file.
|
||||
```
|
||||
@reboot <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
To remove all cron jobs for the current user:
|
||||
```
|
||||
$ crontab -r
|
||||
|
||||
```
|
||||
|
||||
There is also a dedicated website named [**crontab.guru**][4] for learning cron jobs examples. This site provides a lot of cron job examples.
|
||||
|
||||
For more details, check man pages.
|
||||
```
|
||||
$ man crontab
|
||||
|
||||
```
|
||||
|
||||
And, that’s all for now. At this point, you might have a basic understanding of cron jobs and how to use them in real time. More good stuffs to come. Stay tuned!!
|
||||
|
||||
Cheers!
|
||||
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.ostechnix.com/a-beginners-guide-to-cron-jobs/
|
||||
|
||||
作者：[SK][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://www.ostechnix.com/author/sk/
|
||||
[1]:data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7
|
||||
[2]:http://www.ostechnix.com/wp-content/uploads/2018/05/cron-job-format-1.png
|
||||
[3]:http://www.ostechnix.com/wp-content/uploads/2018/05/cron-jobs-1.png
|
||||
[4]:https://crontab.guru/
|
||||
@ -1,3 +1,6 @@
|
||||
Translating by MjSeven
|
||||
|
||||
|
||||
4 Firefox extensions to install now
|
||||
======
|
||||
|
||||
|
||||
@ -1,3 +1,5 @@
|
||||
pinewall translating
|
||||
|
||||
A reading list for Linux and open source fans
|
||||
======
|
||||
|
||||
|
||||
@ -1,123 +0,0 @@
|
||||
apply for translation.
|
||||
|
||||
How to kill a process or stop a program in Linux
|
||||
======
|
||||
|
||||
|
||||
When a process misbehaves, you might sometimes want to terminate or kill it. In this post, we'll explore a few ways to terminate a process or an application from the command line as well as from a graphical interface, using [gedit][1] as a sample application.
|
||||
|
||||
### Using the command line/termination characters
|
||||
|
||||
#### Ctrl + C
|
||||
|
||||
One problem invoking `gedit` from the command line (if you are not using `gedit &`) is that it will not free up the prompt, so that shell session is blocked. In such cases, Ctrl+C (the Control key in combination with 'C') comes in handy. That will terminate `gedit` and all work will be lost (unless the file was saved). Ctrl+C sends the `SIGINT` signal to `gedit`. This is a stop signal whose default action is to terminate the process. It instructs the shell to stop `gedit` and return to the main loop, and you'll get the prompt back.
|
||||
```
|
||||
$ gedit
|
||||
|
||||
^C
|
||||
|
||||
```
|
||||
|
||||
#### Ctrl + Z
|
||||
|
||||
This is called a suspend character. It sends a `SIGTSTP` signal to process. This is also a stop signal, but the default action is not to kill but to suspend the process.
|
||||
|
||||
It will stop (kill/terminate) `gedit` and return the shell prompt.
|
||||
```
|
||||
$ gedit
|
||||
|
||||
^Z
|
||||
|
||||
[1]+ Stopped gedit
|
||||
|
||||
$
|
||||
|
||||
```
|
||||
|
||||
Once the process is suspended (in this case, `gedit`), it is not possible to write or do anything in `gedit`. In the background, the process becomes a job. This can be verified by the `jobs` command.
|
||||
```
|
||||
$ jobs
|
||||
|
||||
[1]+ Stopped gedit
|
||||
|
||||
```
|
||||
|
||||
`jobs` allows you to control multiple processes within a single shell session. You can stop, resume, and move jobs to the background or foreground as needed.
|
||||
|
||||
Let's resume `gedit` in the background and free up a prompt to run other commands. You can do this using the `bg` command, followed by job ID (notice `[1]` from the output of `jobs` above. `[1]` is the job ID).
|
||||
```
|
||||
$ bg 1
|
||||
|
||||
[1]+ gedit &
|
||||
|
||||
```
|
||||
|
||||
This is similar to starting `gedit` with `&,`:
|
||||
```
|
||||
$ gedit &
|
||||
|
||||
```
|
||||
|
||||
### Using kill
|
||||
|
||||
`kill` allows fine control over signals, enabling you to signal a process by specifying either a signal name or a signal number, followed by a process ID, or PID.
|
||||
|
||||
What I like about `kill` is that it can also work with job IDs. Let's start `gedit` in the background using `gedit &`. Assuming I have a job ID of `gedit` from the `jobs` command, let's send `SIGINT` to `gedit`:
|
||||
```
|
||||
$ kill -s SIGINT %1
|
||||
|
||||
```
|
||||
|
||||
Note that the job ID should be prefixed with `%`, or `kill` will consider it a PID.
|
||||
|
||||
`kill` can work without specifying a signal explicitly. In that case, the default action is to send `SIGTERM`, which will terminate the process. Execute `kill -l` to list all signal names, and use the `man kill` command to read the man page.
|
||||
|
||||
### Using killall
|
||||
|
||||
If you don't want to specify a job ID or PID, `killall` lets you specify a process by name. The simplest way to terminate `gedit` using `killall` is:
|
||||
```
|
||||
$ killall gedit
|
||||
|
||||
```
|
||||
|
||||
This will kill all the processes with the name `gedit`. Like `kill`, the default signal is `SIGTERM`. It has the option to ignore case using `-I`:
|
||||
```
|
||||
$ gedit &
|
||||
|
||||
[1] 14852
|
||||
|
||||
|
||||
|
||||
$ killall -I GEDIT
|
||||
|
||||
[1]+ Terminated gedit
|
||||
|
||||
```
|
||||
|
||||
To learn more about various flags provided by `killall` (such as `-u`, which allows you to kill user-owned processes) check the man page (`man killall`)
|
||||
|
||||
### Using xkill
|
||||
|
||||
Have you ever encountered an issue where a media player, such as [VLC][2], grayed out or hung? Now you can find the PID and kill the application using one of the commands listed above or use `xkill`.
|
||||
|
||||
![Using xkill][3]
|
||||
|
||||
`xkill` allows you to kill a window using a mouse. Simply execute `xkill` in a terminal, which should change the mouse cursor to an **x** or a tiny skull icon. Click **x** on the window you want to close. Be careful using `xkill`, though—as its man page explains, it can be dangerous. You have been warned!
|
||||
|
||||
Refer to the man page of each command for more information. You can also explore commands like `pkill` and `pgrep`.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/5/how-kill-process-stop-program-linux
|
||||
|
||||
作者：[Sachin Patil][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://opensource.com/users/psachin
|
||||
[1]:https://wiki.gnome.org/Apps/Gedit
|
||||
[2]:https://www.videolan.org/vlc/index.html
|
||||
[3]:https://opensource.com/sites/default/files/styles/panopoly_image_original/public/uploads/xkill_gedit.png?itok=TBvMw0TN (Using xkill)
|
||||
@ -1,100 +0,0 @@
|
||||
pinewall translating
|
||||
|
||||
Creating small containers with Buildah
|
||||
======
|
||||
|
||||
I recently joined Red Hat after many years working for another tech company. In my previous job, I developed a number of different software products that were successful but proprietary. Not only were we legally compelled to not share the software outside of the company, we often didn’t even share it within the company. At the time, that made complete sense to me: The company spent time, energy, and budget developing the software, so they should protect and claim the rewards it garnered.
|
||||
|
||||
Fast-forward to a year ago, when I joined Red Hat and developed a completely different mindset. One of the first things I jumped into was the [Buildah project][1]. It facilitates building Open Container Initiative (OCI) images, and it is especially good at allowing you to tailor the size of the image that is created. At that time Buildah was in its very early stages, and there were some warts here and there that weren’t quite production-ready.
|
||||
|
||||
Being new to the project, I made a few minor changes, then asked where the company’s internal git repository was so that I could push my changes. The answer: Nothing internal, just push your changes to GitHub. I was baffled—sending my changes out to GitHub would mean anyone could look at that code and use it for their own projects. Plus, the code still had a few warts, so that just seemed so counterintuitive. But being the new guy, I shook my head in wonder and pushed the changes out.
|
||||
|
||||
A year later, I’m now convinced of the power and value of open source software. I’m still working on Buildah, and we recently had an issue that illustrates that power and value. The issue, titled [Buildah images not so small?][2] , was raised by Tim Dudgeon (@tdudgeon). To summarize, he noted that images created by Buildah were bigger than those created by Docker, even though the Buildah images didn’t contain the extra "fluff" he saw in the Docker images.
|
||||
|
||||
For comparison he first did:
|
||||
```
|
||||
$ docker pull centos:7
|
||||
$ docker images
|
||||
REPOSITORY TAG IMAGE ID CREATED SIZE
|
||||
docker.io/centos 7 2d194b392dd1 2 weeks ago 195 MB
|
||||
```
|
||||
|
||||
He noted that the size of the Docker image was 195MB. Tim then created a minimal (scratch) image using Buildah, with only the `coreutils` and `bash` packages added to the image, using the following script:
|
||||
```
|
||||
$ cat ./buildah-base.sh
|
||||
#!/bin/bash
|
||||
|
||||
set -x
|
||||
|
||||
# build a minimal image
|
||||
newcontainer=$(buildah from scratch)
|
||||
scratchmnt=$(buildah mount $newcontainer)
|
||||
|
||||
# install the packages
|
||||
yum install --installroot $scratchmnt bash coreutils --releasever 7 --setopt install_weak_deps=false -y
|
||||
yum clean all -y --installroot $scratchmnt --releasever 7
|
||||
|
||||
sudo buildah config --cmd /bin/bash $newcontainer
|
||||
|
||||
# set some config info
|
||||
buildah config --label name=centos-base $newcontainer
|
||||
|
||||
# commit the image
|
||||
buildah unmount $newcontainer
|
||||
buildah commit $newcontainer centos-base
|
||||
|
||||
$ sudo ./buildah-base.sh
|
||||
|
||||
$ sudo buildah images
|
||||
IMAGE ID IMAGE NAME CREATED AT SIZE
|
||||
8379315d3e3e docker.io/library/centos-base:latest Mar 25, 2018 17:08 212.1 MB
|
||||
```
|
||||
|
||||
Tim wondered why the image was 17MB larger, because `python` and `yum` were not installed in the Buildah image, whereas they were installed in the Docker image. This set off quite the discussion in the GitHub issue, as it was not at all an expected result.
|
||||
|
||||
What was great about the discussion was that not only were Red Hat folks involved, but several others from outside as well. In particular, a lot of great discussion and investigation was led by GitHub user @pixdrift, who noted that the documentation and locale-archive were chewing up a little more than 100MB of space in the Buildah image. Pixdrift suggested forcing locale in the yum installer and provided this updated `buildah-bash.sh` script with those changes:
|
||||
```
|
||||
#!/bin/bash
|
||||
|
||||
set -x
|
||||
|
||||
# build a minimal image
|
||||
newcontainer=$(buildah from scratch)
|
||||
scratchmnt=$(buildah mount $newcontainer)
|
||||
|
||||
# install the packages
|
||||
yum install --installroot $scratchmnt bash coreutils --releasever 7 --setopt=install_weak_deps=false --setopt=tsflags=nodocs --setopt=override_install_langs=en_US.utf8 -y
|
||||
yum clean all -y --installroot $scratchmnt --releasever 7
|
||||
|
||||
sudo buildah config --cmd /bin/bash $newcontainer
|
||||
|
||||
# set some config info
|
||||
buildah config --label name=centos-base $newcontainer
|
||||
|
||||
# commit the image
|
||||
buildah unmount $newcontainer
|
||||
buildah commit $newcontainer centos-base
|
||||
```
|
||||
|
||||
When Tim ran this new script, the image size shrank to 92MB, shedding 120MB from the original Buildah image size and getting closer to the expected size; however, engineers being engineers, a size savings of 56% wasn’t enough. The discussion went further, involving how to remove individual locale packages to save even more space. To see more details of the discussion, click the [Buildah images not so small?][2] link. Who knows—maybe you’ll have a helpful tip, or better yet, become a contributor for Buildah. On a side note, this solution illustrates how the Buildah software can be used to quickly and easily create a minimally sized container that's loaded only with the software that you need to do your job efficiently. As a bonus, it doesn’t require a daemon to be running.
|
||||
|
||||
This image-sizing issue drove home the power of open source software for me. A number of people from different companies all collaborated to solve a problem through open discussion in a little over a day. Although no code changes were created to address this particular issue, there have been many code contributions to Buildah from contributors outside of Red Hat, and this has helped to make the project even better. These contributions have served to get a wider variety of talented people to look at the code than ever would have if it were a proprietary piece of software stuck in a private git repository. It’s taken only a year to convert me to the [open source way][3], and I don’t think I could ever go back.
|
||||
|
||||
This article was originally posted at [Project Atomic][4]. Reposted with permission.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/5/containers-buildah
|
||||
|
||||
作者：[Tom Sweeney][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://opensource.com/users/tomsweeneyredhat
|
||||
[1]:https://github.com/projectatomic/buildah
|
||||
[2]:https://github.com/projectatomic/buildah/issues/532
|
||||
[3]:https://twitter.com/opensourceway
|
||||
[4]:http://www.projectatomic.io/blog/2018/04/open-source-what-a-concept/
|
||||
@ -1,262 +0,0 @@
|
||||
pinewall translating
|
||||
|
||||
Get more done at the Linux command line with GNU Parallel
|
||||
======
|
||||
|
||||
|
||||
|
||||
Do you ever get the funny feeling that your computer isn't quite as fast as it should be? I used to feel that way, and then I found GNU Parallel.
|
||||
|
||||
GNU Parallel is a shell utility for executing jobs in parallel. It can parse multiple inputs, thereby running your script or command against sets of data at the same time. You can use all your CPU at last!
|
||||
|
||||
If you've ever used `xargs`, you already know how to use Parallel. If you don't, then this article teaches you, along with many other use cases.
|
||||
|
||||
### Installing GNU Parallel
|
||||
|
||||
GNU Parallel may not come pre-installed on your Linux or BSD computer. Install it from your repository or ports collection. For example, on Fedora:
|
||||
```
|
||||
$ sudo dnf install parallel
|
||||
|
||||
```
|
||||
|
||||
Or on NetBSD:
|
||||
```
|
||||
# pkg_add parallel
|
||||
|
||||
```
|
||||
|
||||
If all else fails, refer to the [project homepage][1].
|
||||
|
||||
### From serial to parallel
|
||||
|
||||
As its name suggests, Parallel's strength is that it runs jobs in parallel rather than, as many of us still do, sequentially.
|
||||
|
||||
When you run one command against many objects, you're inherently creating a queue. Some number of objects can be processed by the command, and all the other objects just stand around and wait their turn. It's inefficient. Given enough data, there's always going to be a queue, but instead of having just one queue, why not have lots of small queues?
|
||||
|
||||
Imagine you have a folder full of images you want to convert from JPEG to PNG. There are many ways to do this. There's the manual way of opening each image in GIMP and exporting it to the new format. That's usually the worst possible way. It's not only time-intensive, it's labor-intensive.
|
||||
|
||||
A pretty neat variation on this theme is the shell-based solution:
|
||||
```
|
||||
$ convert 001.jpeg 001.png
|
||||
|
||||
$ convert 002.jpeg 002.png
|
||||
|
||||
$ convert 003.jpeg 003.png
|
||||
|
||||
... and so on ...
|
||||
|
||||
```
|
||||
|
||||
It's a great trick when you first learn it, and at first it's a vast improvement. No need for a GUI and constant clicking. But it's still labor-intensive.
|
||||
|
||||
Better still:
|
||||
```
|
||||
$ for i in *jpeg; do convert $i $i.png ; done
|
||||
|
||||
```
|
||||
|
||||
This, at least, sets the job(s) in motion and frees you up to do more productive things. The problem is, it's still a serial process. One image gets converted, and then the next one in the queue steps up for conversion, and so on until the queue has been emptied.
|
||||
|
||||
With Parallel:
|
||||
```
|
||||
$ find . -name "*jpeg" | parallel -I% --max-args 1 convert % %.png
|
||||
|
||||
```
|
||||
|
||||
This is a combination of two commands: the `find` command, which gathers the objects you want to operate on, and the `parallel` command, which sorts through the objects and makes sure everything gets processed as required.
|
||||
|
||||
* `find . -name "*jpeg"` finds all files in the current directory that end in `jpeg`.
|
||||
* `parallel` invokes GNU Parallel.
|
||||
* `-I%` creates a placeholder, called `%`, to stand in for whatever `find` hands over to Parallel. You use this because otherwise you'd have to manually write a new command for each result of `find`, and that's exactly what you're trying to avoid.
|
||||
* `--max-args 1` limits the rate at which Parallel requests a new object from the queue. Since the command Parallel is running requires only one file, you limit the rate to 1. Were you doing a more complex command that required two files (such as `cat 001.txt 002.txt > new.txt`), you would limit the rate to 2.
|
||||
* `convert % %.png` is the command you want to run in Parallel.
|
||||
|
||||
|
||||
|
||||
The result of this command is that `find` gathers all relevant files and hands them over to `parallel`, which launches a job and immediately requests the next in line. Parallel continues to do this for as long as it is safe to launch new jobs without crippling your computer. As old jobs are completed, it replaces them with new ones, until all the data provided to it has been processed. What took 10 minutes before might take only 5 or 3 with Parallel.
|
||||
|
||||
### Multiple inputs
|
||||
|
||||
The `find` command is an excellent gateway to Parallel as long as you're familiar with `find` and `xargs` (collectively called GNU Find Utilities, or `findutils`). It provides a flexible interface that many Linux users are already comfortable with and is pretty easy to learn if you're a newcomer.
|
||||
|
||||
The `find` command is fairly straightforward: you provide `find` with a path to a directory you want to search and some portion of the file name you want to search for. Use wildcard characters to cast your net wider; in this example, the asterisk indicates anything, so `find` locates all files that end with the string `searchterm`:
|
||||
```
|
||||
$ find /path/to/directory -name "*searchterm"
|
||||
|
||||
```
|
||||
|
||||
By default, `find` returns the results of its search one item at a time, with one item per line:
|
||||
```
|
||||
$ find ~/graphics -name "*jpg"
|
||||
|
||||
/home/seth/graphics/001.jpg
|
||||
|
||||
/home/seth/graphics/cat.jpg
|
||||
|
||||
/home/seth/graphics/penguin.jpg
|
||||
|
||||
/home/seth/graphics/IMG_0135.jpg
|
||||
|
||||
```
|
||||
|
||||
When you pipe the results of `find` to `parallel`, each item on each line is treated as one argument to the command that `parallel` is arbitrating. If, on the other hand, you need to process more than one argument in one command, you can split up the way the data in the queue is handed over to `parallel`.
|
||||
|
||||
Here's a simple, unrealistic example, which I'll later turn into something more useful. You can follow along with this example, as long as you have GNU Parallel installed.
|
||||
|
||||
Assume you have four files. List them, one per line, to see exactly what you have:
|
||||
```
|
||||
$ echo ada > ada ; echo lovelace > lovelace
|
||||
|
||||
$ echo richard > richard ; echo stallman > stallman
|
||||
|
||||
$ ls -1
|
||||
|
||||
ada
|
||||
|
||||
lovelace
|
||||
|
||||
richard
|
||||
|
||||
stallman
|
||||
|
||||
```
|
||||
|
||||
You want to combine two files into a third that contains the contents of both files. This requires that Parallel has access to two files, so the `-I%` variable won't work in this case.
|
||||
|
||||
Parallel's default behavior is basically invisible:
|
||||
```
|
||||
$ ls -1 | parallel echo
|
||||
|
||||
ada
|
||||
|
||||
lovelace
|
||||
|
||||
richard
|
||||
|
||||
stallman
|
||||
|
||||
```
|
||||
|
||||
Now tell Parallel you want to get two objects per job:
|
||||
```
|
||||
$ ls -1 | parallel --max-args=2 echo
|
||||
|
||||
ada lovelace
|
||||
|
||||
richard stallman
|
||||
|
||||
```
|
||||
|
||||
Now the lines have been combined. Specifically, two results from `ls -1` are passed to Parallel all at once. That's the right number of arguments for this task, but they're effectively one argument right now: "ada lovelace" and "richard stallman." What you actually want is two distinct arguments per job.
|
||||
|
||||
Luckily, that technicality is parsed by Parallel itself. If you set `--max-args` to `2`, you get two variables, `{1}` and `{2}`, representing the first and second parts of the argument:
|
||||
```
|
||||
$ ls -1 | parallel --max-args=2 cat {1} {2} ">" {1}_{2}.person
|
||||
|
||||
```
|
||||
|
||||
In this command, the variable `{1}` is ada or richard (depending on which job you look at) and `{2}` is either `lovelace` or `stallman`. The contents of the files are redirected with a redirect symbol in quotes (the quotes grab the redirect symbol from Bash so Parallel can use it) and placed into new files called `ada_lovelace.person` and `richard_stallman.person`.
|
||||
```
|
||||
$ ls -1
|
||||
|
||||
ada
|
||||
|
||||
ada_lovelace.person
|
||||
|
||||
lovelace
|
||||
|
||||
richard
|
||||
|
||||
richard_stallman.person
|
||||
|
||||
stallman
|
||||
|
||||
|
||||
|
||||
$ cat ada_*person
|
||||
|
||||
ada lovelace
|
||||
|
||||
$ cat ri*person
|
||||
|
||||
richard stallman
|
||||
|
||||
```
|
||||
|
||||
If you spend all day parsing log files that are hundreds of megabytes in size, you might see how parallelized text parsing could be useful to you; otherwise, this is mostly a demonstrative exercise.
|
||||
|
||||
However, this kind of processing is invaluable for more than just text parsing. Here's a real-life example from the film world. Consider a directory of video files and audio files that need to be joined together.
|
||||
```
|
||||
$ ls -1
|
||||
|
||||
12_LS_establishing-manor.avi
|
||||
|
||||
12_wildsound.flac
|
||||
|
||||
14_butler-dialogue-mixed.flac
|
||||
|
||||
14_MS_butler.avi
|
||||
|
||||
...and so on...
|
||||
|
||||
```
|
||||
|
||||
Using the same principles, a simple command can be created so that the files are combined in parallel:
|
||||
```
|
||||
$ ls -1 | parallel --max-args=2 ffmpeg -i {1} -i {2} -vcodec copy -acodec copy {1}.mkv
|
||||
|
||||
```
|
||||
|
||||
### Brute. Force.
|
||||
|
||||
All this fancy input and output parsing isn't to everyone's taste. If you prefer a more direct approach, you can throw commands at Parallel and walk away.
|
||||
|
||||
First, create a text file with one command on each line:
|
||||
```
|
||||
$ cat jobs2run
|
||||
|
||||
bzip2 oldstuff.tar
|
||||
|
||||
oggenc music.flac
|
||||
|
||||
opusenc ambiance.wav
|
||||
|
||||
convert bigfile.tiff small.jpeg
|
||||
|
||||
ffmepg -i foo.avi -v:b 12000k foo.mp4
|
||||
|
||||
xsltproc --output build/tmp.fo style/dm.xsl src/tmp.xml
|
||||
|
||||
bzip2 archive.tar
|
||||
|
||||
```
|
||||
|
||||
Then hand the file over to Parallel:
|
||||
```
|
||||
$ parallel --jobs 6 < jobs2run
|
||||
|
||||
```
|
||||
|
||||
And now all jobs in your file are run in Parallel. If more jobs exist than jobs allowed, a queue is formed and maintained by Parallel until all jobs have run.
|
||||
|
||||
### Much, much more
|
||||
|
||||
GNU Parallel is a powerful and flexible tool, with far more use cases than can fit into this article. Its man page provides examples of really cool things you can do with it, from remote execution over SSH to incorporating Bash functions into your Parallel commands. There's even an extensive demonstration series on [YouTube][2], so you can learn from the GNU Parallel team directly. The GNU Parallel lead maintainer has also just released the command's official guide, available from [Lulu.com][3].
|
||||
|
||||
GNU Parallel has the power to change the way you compute, and if doesn't do that, it will at the very least change the time your computer spends computing. Try it today!
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/5/gnu-parallel
|
||||
|
||||
作者：[Seth Kenlon][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/seth
|
||||
[1]:https://www.gnu.org/software/parallel
|
||||
[2]:https://www.youtube.com/watch?v=OpaiGYxkSuQ&list=PL284C9FF2488BC6D1
|
||||
[3]:http://www.lulu.com/shop/ole-tange/gnu-parallel-2018/paperback/product-23558902.html
|
||||
133
sources/tech/20180514 A CLI Game To Learn Vim Commands.md
Normal file
133
sources/tech/20180514 A CLI Game To Learn Vim Commands.md
Normal file
@ -0,0 +1,133 @@
|
||||
A CLI Game To Learn Vim Commands
|
||||
======
|
||||
|
||||
|
||||
|
||||
Howdy, Vim users! Today, I stumbled upon a cool utility to sharpen your Vim usage skills. Vim is a great editor to write and edit code. However, some of you (including me) are still struggling with the steep learning curve. Not anymore! Meet **PacVim** , a CLI game that helps you to learn Vim commands. PacVim is inspired by the classic game [**PacMan**][1] and it gives you plenty of practice with Vim commands in a fun and interesting way. Simply put, PacVim is a fun, free way to learn about the vim commands in-depth. Please do not confuse PacMan with [**pacman**][2] (the arch Linux package manager). PacMan is a classic, popular arcade game released in the 1980s.
|
||||
|
||||
In this brief guide, we will see how to install and use PacVim in Linux.
|
||||
|
||||
### Install PacVim
|
||||
|
||||
First, install **Ncurses** library and **development tools** as described in the following links.
|
||||
|
||||
Please note that this game may not compile and install properly without gcc version 4.8.X or higher. I tested PacVim on Ubuntu 18.04 LTS and it worked perfectly.
|
||||
|
||||
Once Ncurses and gcc are installed, run the following commands to install PacVim.
|
||||
```
|
||||
$ git clone https://github.com/jmoon018/PacVim.git
|
||||
$ cd PacVim
|
||||
$ sudo make install
|
||||
|
||||
```
|
||||
|
||||
## Learn Vim Commands Using PacVim
|
||||
|
||||
### Start PacVim game
|
||||
|
||||
To play this game, just run:
|
||||
```
|
||||
$ pacvim [LEVEL_NUMER] [MODE]
|
||||
|
||||
```
|
||||
|
||||
For example, the following command starts the game in 5th level with normal mode.
|
||||
```
|
||||
$ pacvim 5 n
|
||||
|
||||
```
|
||||
|
||||
Here, **“5”** represents the level and **“n”** represents the mode. There are two modes
|
||||
|
||||
* **n** – normal mode.
|
||||
* **h** – hard mode.
|
||||
|
||||
|
||||
|
||||
The default mode is h, which is hard:
|
||||
|
||||
To start from the beginning (0 level), just run:
|
||||
```
|
||||
$ pacvim
|
||||
|
||||
```
|
||||
|
||||
Here is the sample output from my Ubuntu 18.04 LTS system.
|
||||
|
||||
![][4]
|
||||
|
||||
To begin the game, just press **ENTER**.
|
||||
|
||||
![][5]
|
||||
|
||||
Now start playing the game. Read the next chapter to know how to play.
|
||||
|
||||
To quit, press **ESC** or **q**.
|
||||
|
||||
The following command starts the game in 5th level with hard mode.
|
||||
```
|
||||
$ pacvim 5 h
|
||||
|
||||
```
|
||||
|
||||
Or,
|
||||
```
|
||||
$ pacvim 5
|
||||
|
||||
```
|
||||
|
||||
### How to play PacVim?
|
||||
|
||||
The usage of PacVim is very similar to PacMan.
|
||||
|
||||
You must run over all the characters on the screen while avoiding the ghosts (the red color characters).
|
||||
|
||||
PacVim has two special obstacles:
|
||||
|
||||
1. You cannot move into the walls (yellow color). You must use vim motions to jump over them.
|
||||
2. If you step on a tilde character (cyan `~`), you lose!
|
||||
|
||||
|
||||
|
||||
You are given three lives. You gain a life each time you beat level 0, 3, 6, 9, etc. There are 10 levels in total, starting from 0 to 9. After beating the 9th level, the game is reset to the 0th level, but the ghosts move faster.
|
||||
|
||||
**Winning conditions**
|
||||
|
||||
Use vim commands to move the cursor over the letters and highlight them. After all letters are highlighted, you win and proceed to the next level.
|
||||
|
||||
**Losing conditions**
|
||||
|
||||
If you touch a ghost (indicated by a **red G** ) or a **tilde** character, you lose a life. If you have less than 0 lives, you will lose the entire game.
|
||||
|
||||
Here is the list of Implemented Commands:-
|
||||
|
||||
key what it does q quit the game h move left j move down k move up l move right w move forward to next word beginning W move forward to next WORD beginning e move forward to next word ending E move forward to next WORD ending b move backward to next word beginning B move backward to next WORD beginning $ move to the end of the line 0 move to the beginning of the line gg/1G move to the beginning of the first line numberG move to the beginning of the line given by number G move to the beginning of the last line ^ move to the first word at the current line & 1337 cheatz (beat current level)
|
||||
|
||||
After playing couple levels, you may notice there is a slight improvement in Vim usage. Keep playing this game once in a while until you mastering the Vim usage.
|
||||
|
||||
**Suggested read:**
|
||||
|
||||
And, that’s all for now. Hope this was useful. Playing PacVim is fun, interesting and keep you occupied. At the same time, you should be able to thoroughly learn the enough Vim commands. Give it a try, you won’t be disappointed.
|
||||
|
||||
More good stuffs to come. Stay tuned!
|
||||
|
||||
Cheers!
|
||||
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.ostechnix.com/pacvim-a-cli-game-to-learn-vim-commands/
|
||||
|
||||
作者：[SK][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://www.ostechnix.com/author/sk/
|
||||
[1]:https://en.wikipedia.org/wiki/Pac-Man
|
||||
[2]:https://www.ostechnix.com/getting-started-pacman/
|
||||
[4]:http://www.ostechnix.com/wp-content/uploads/2018/05/pacvim-1.png
|
||||
[5]:http://www.ostechnix.com/wp-content/uploads/2018/05/pacvim-2.png
|
||||
@ -0,0 +1,216 @@
|
||||
MapTool: A robust, flexible virtual tabletop for RPGs
|
||||
======
|
||||
|
||||
|
||||
|
||||
When I was looking for a virtual tabletop for role-playing games (RPGs), either for local play or for playing on a network with family and friends around the world, I had several criteria. First, I wanted a platform I could use offline while I prepped a campaign. Second, I didn't want something that came with the burden of being a social network. I wanted the equivalent of a [Sword Coast][1] campaign-setting [boxed set][2] that I could put on my digital "shelf" and use when I wanted, how I wanted.
|
||||
|
||||
I looked at it this way: I purchased [AD&D 2nd edition][3] as a hardcover book, so even though there have since been many great releases, I can still play AD&D 2nd edition today. The same goes for my digital life. When I want to use my digital maps and tokens or go back to an old campaign, I want access to them regardless of circumstance.
|
||||
|
||||
|
||||
|
||||
### Virtual tabletop
|
||||
|
||||
[MapTool][4] is the flagship product of the RPTools software suite. It's a Java application, so it runs on any operating system that can run Java, which is basically every computer. It's also open source and costs nothing to use, although RPTools accepts [donations][5] if you're so inclined.
|
||||
|
||||
### Installing MapTool
|
||||
|
||||
Download MapTool from [rptools.net][6].
|
||||
|
||||
It's likely that you already have Java installed; if not, download and install it from [java.net][7]. If you're not sure whether you have it installed or not, you can download MapTool first, try to run it, and install Java if it fails to run.
|
||||
|
||||
### Using MapTool
|
||||
|
||||
If you're a game master (GM), MapTool is a great way to provide strategic maps for battles and exploration without investing in physical maps, tokens, or miniatures.
|
||||
|
||||
MapTool is a full-featured virtual tabletop. You can load maps into it, import custom tokens, track initiative order and health, and save campaigns. You can use it locally at your game table, or you can share your session with remote gamers so they can follow along. There are other virtual tabletops out there, but MapTool is the only one you own, part and parcel.
|
||||
|
||||
To load a map into MapTool, all you need is a PNG or JPEG version of a map.
|
||||
|
||||
1. Launch MapTool, then go to the **Map** menu and select **New Map**.
|
||||
2. In the **Map Properties** window that appears, click the **Map** button.
|
||||
3. Click the **Filesystem** button in the bottom-left corner to locate your map graphic on your hard drive.
|
||||
|
||||
|
||||
|
||||
If you have no digital maps yet, there are dozens of map packs available from [Open Gaming Store][8], so you're sure to find a map regardless of where your adventure path may take you.
|
||||
|
||||
MapTool, like most virtual tabletops, expects a PNG or JPEG. I maintain a simple [Image Magick][9] script to convert maps from PDF to PNG. The script runs on Linux, BSD, or Mac and is probably also easily adapted to PowerShell.
|
||||
```
|
||||
#!/usr/bin/env bash
|
||||
|
||||
#GNU All-Permissive http://www.gnu.org/licenses
|
||||
|
||||
|
||||
|
||||
CMD=`which convert` || echo "Image Magick not found in PATH."
|
||||
|
||||
ARG=("${@}")
|
||||
|
||||
ARRAYSIZE=${#ARG[*]}
|
||||
|
||||
|
||||
|
||||
while [ True ]; do
|
||||
|
||||
for item in "${ARG[@]}"; do
|
||||
|
||||
$CMD "${item}" `basename "${item}" .pdf`.jpg || \
|
||||
|
||||
$CMD "${item}" `basename "${item}" .PDF`.jpg
|
||||
|
||||
done
|
||||
|
||||
done
|
||||
|
||||
exit
|
||||
|
||||
```
|
||||
|
||||
If running code like that scares you, there are plenty of PDF-to-image converters, like [GIMP][10], for manually converting a PDF to PNG or JPEG on an as-needed basis.
|
||||
|
||||
#### Adding tokens
|
||||
|
||||
Now that you have a map loaded, it's time to add player characters (PCs) and non-player characters (NPCs). MapTool ships with a modest selection of token graphics, but you can always create and use your own or download more from the internet. In fact, the RPTools website recently linked to [ImmortalNights][11], a website by artist Devin Night, with over 100 tokens for free and purchase.
|
||||
|
||||
1. Click the **Tokens** folder icon in the MapTool **Resource Library** panel.
|
||||
2. In the panel just beneath the **Resource Library** panel, the default tokens appear. You can add your own tokens using the **Add resources to library** option in the **File** menu.
|
||||
3. In the **New token** pop-up dialogue box, give the token a name and PC or NPC designation.
|
||||
|
||||
|
||||
|
||||
4. Once the token is on the map, it should align perfectly with the map grid. If it doesn't, you can adjust the grid.
|
||||
5. Right-click on the token to adjust its rotation, size, and other attributes.
|
||||
|
||||
|
||||
|
||||
#### Adjusting the grid
|
||||
|
||||
By default, MapTool provides an invisible 50x50 square grid over any map. If your map graphic already has a grid on it, you can adjust MapTool's grid to match your graphic.
|
||||
|
||||
1. Select **Adjust grid** in the **Map** menu. A grid overlay appears over your map.
|
||||
2. Click and drag the overlay grid so one overlay square sits inside one of your map graphic's grid squares.
|
||||
3. Adjust the **Grid Size** pixel value in the property box in the top-right corner of the MapTool window.
|
||||
4. When finished, click the property box's **Close** button.
|
||||
|
||||
|
||||
|
||||
You can set the default grid size using the **Preferences** selection in the **Edit** menu. For instance, I do this for [Paizo][12] maps on my 96dpi screen.
|
||||
|
||||
MapTool's default assumes each grid block is a five-foot square, but you can adjust that if you're using a wide area representing long-distance travel or if you've drawn a custom map to your own scale.
|
||||
|
||||
### Sharing the screen locally
|
||||
|
||||
While you can use MapTool solely as a GM tool to help keep track of character positions, you can also share it with your players.
|
||||
|
||||
If you're using MapTool as a digital replacement for physical maps at your game table, you can just plug your computer into your TV. That's the simplest way to share the map with everyone at your table.
|
||||
|
||||
Another alternative is to use MapTool's built-in server. If your players are physically sitting in the same room and on the same network, select **Start server** from the **File** menu.
|
||||
|
||||
The only required field is a name for the GM. The default port is 51234. If you don't know what that means, that's OK; a port is just a flag identifying where a service like MapTool is running.
|
||||
|
||||
Once your MapTool server is started, players can connect by selecting **Connect to server** in the **File** menu.
|
||||
|
||||
|
||||
|
||||
A name is required, but no password is needed unless the GM has set one when starting the server.
|
||||
|
||||
The IP address is your local IP address, so it starts with either 192.168 or 10. If you don't know your local IP address, you can check it from your computer's networking control panel. On Linux, you can also find it by typing:
|
||||
```
|
||||
$ ip -4 -ts a
|
||||
|
||||
```
|
||||
|
||||
And on BSD or Mac:
|
||||
```
|
||||
$ ifconfig
|
||||
|
||||
```
|
||||
|
||||
On Windows, open PowerShell from your **Start** menu and type:
|
||||
```
|
||||
ipconfig
|
||||
|
||||
```
|
||||
|
||||
|
||||
|
||||
If your players have trouble connecting, there are two likely causes:
|
||||
|
||||
* You forgot to start the server. Start it and have your players try again.
|
||||
* You have a firewall running on your computer. If you're on your home network, it's safe to deactivate your firewall or to tell it to permit traffic on port 51234. If you're in a public gaming space, you should not lower your firewall, but it's safe to permit traffic on port 51234 as long as you have set a password for your MapTool server.
|
||||
|
||||
|
||||
|
||||
### Sharing the screen worldwide
|
||||
|
||||
If you're playing remotely with people all over the world, letting them into your private MapTool server is a little more complex to set up, but you only have to do it once and then you're set.
|
||||
|
||||
#### Router
|
||||
|
||||
The first device that needs to be adjusted is your home router. This is the box you got from your internet service provider. You might also call it your modem.
|
||||
|
||||
Every device is different, so there's no way for me to definitively tell you what you need to click on to adjust your settings. Generally, you access your home router through a web browser. Your router's address is often printed on the bottom of the router and begins with either 192.168 or 10.
|
||||
|
||||
Navigate to the router address and log in with the credentials you were provided when you got your internet service. It's often as simple as `admin` with a numeric password (sometimes this password is printed on the router, too). If you don't know the login, call your internet provider and ask for details.
|
||||
|
||||
Different routers use different terms for the same thing; keywords to look for are **Port forwarding** , **Virtual server** , and **Firewall**. Whatever your router calls it, you want to accept traffic coming to port 51234 of your router and forward that traffic to the same port of your personal computer's IP address.
|
||||
|
||||
|
||||
|
||||
If you're confused, search the internet for the term "port forwarding" and your router's brand name. This isn't an uncommon task for PC gamers, so instructions are out there.
|
||||
|
||||
#### Finding your external IP address
|
||||
|
||||
Now you're allowing traffic through the MapTool port, so you need to tell your players where to go.
|
||||
|
||||
1. Get your worldwide IP address at [icanhazip.com][13].
|
||||
2. Start the MapTool server from the **File** menu. Set a password for safety.
|
||||
3. Have players select **Connect to server** from the **File** menu.
|
||||
4. In the **Connect to server** window, have players click the **Direct** tab and enter a username, password, and your IP address.
|
||||
|
||||
|
||||
|
||||
### Features a-plenty
|
||||
|
||||
This has been a brief overview of things you can do with MapTool. It has many other features, including an initiative tracker, adjustable tokens visibility (hide treasure and monsters from your players!), impersonation, line-of-sight (conceal hidden doors behind statues or other structures!), and fog of war.
|
||||
|
||||
It can serve just as a digital battle map, or it can be the centerpiece of your tabletop game.
|
||||
|
||||
|
||||
|
||||
### Why MapTool?
|
||||
|
||||
Before you comment about them: Yes, there are a few virtual tabletop services online, and some of them are very good. They provide a good supply of games looking for players and players looking for games. If you can't find your fellow gamers locally, online tabletops are a great solution.
|
||||
|
||||
By contrast, some people are not fans of social networking, so we shy away from sites that excitedly "bring people together." I've got friends to game with, and we're happy to build and set up our own infrastructure. We don't need to sign up for yet another site; we don't need to throw our hats into a great big online bucket and register when and how we game.
|
||||
|
||||
Ultimately, I like MapTool because I have it with me whether or not I'm online. I can plan a campaign, populate it with graphics, and set up all my maps in advance without depending on having internet access. It's almost like doing the frontend programming for a video game, knowing that the backend "technology" will all happen in the player's minds on game night.
|
||||
|
||||
If you're looking for a robust and flexible virtual tabletop, try MapTool!
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/5/maptool
|
||||
|
||||
作者：[Seth Kenlon][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/seth
|
||||
[1]:https://en.wikibooks.org/wiki/Dungeons_%26_Dragons/Commercial_settings/Forgotten_Realms/Sword_Coast
|
||||
[2]:https://en.wikipedia.org/wiki/Dungeons_%26_Dragons_campaign_settings
|
||||
[3]:https://en.wikipedia.org/wiki/Editions_of_Dungeons_%26_Dragons#Advanced_Dungeons_&_Dragons_2nd_edition
|
||||
[4]:http://www.rptools.net/toolbox/maptool/
|
||||
[5]:http://www.rptools.net/donate/
|
||||
[6]:http://www.rptools.net/downloadsw/
|
||||
[7]:http://jdk.java.net/8
|
||||
[8]:https://www.opengamingstore.com/search?q=map
|
||||
[9]:http://www.imagemagick.org/script/index.php
|
||||
[10]:http://gimp.org
|
||||
[11]:http://immortalnights.com/tokenpage.html
|
||||
[12]:http://paizo.com/
|
||||
[13]:http://icanhazip.com/
|
||||
@ -0,0 +1,92 @@
|
||||
Give Your Linux Desktop a Stunning Makeover With Xenlism Themes
|
||||
============================================================
|
||||
|
||||
|
||||
_Brief: Xenlism theme pack provides an aesthetically pleasing GTK theme, colorful icons, and minimalist wallpapers to transform your Linux desktop into an eye-catching setup._
|
||||
|
||||
It’s not every day that I dedicate an entire article to a theme unless I find something really awesome. I used to cover themes and icons regularly. But lately, I preferred having lists of [best GTK themes][6] and icon themes. This is more convenient for me and for you as well as you get to see many beautiful themes in one place.
|
||||
|
||||
After [Pop OS theme][7] suit, Xenlism is another theme that has left me awestruck by its look.
|
||||
|
||||
|
||||
|
||||
Xenlism GTK theme is based on the Arc theme, an inspiration behind so many themes these days. The GTK theme provides Windows buttons similar to macOS which I neither like nor dislike. The GTK theme has a flat, minimalist layout and I like that.
|
||||
|
||||
There are two icon themes in the Xenlism suite. Xenlism Wildfire is an old one and had already made to our list of [best icon themes][8].
|
||||
|
||||
|
||||
Xenlism Wildfire Icons
|
||||
|
||||
Xenlsim Storm is the relatively new icon theme but is equally beautiful.
|
||||
|
||||
|
||||
Xenlism Storm Icons
|
||||
|
||||
Xenlism themes are open source under GPL license.
|
||||
|
||||
### How to install Xenlism theme pack on Ubuntu 18.04
|
||||
|
||||
Xenlism dev provides an easier way of installing the theme pack through a PPA. Though the PPA is available for Ubuntu 16.04, I found the GTK theme wasn’t working with Unity. It works fine with the GNOME desktop in Ubuntu 18.04.
|
||||
|
||||
Open a terminal (Ctrl+Alt+T) and use the following commands one by one:
|
||||
|
||||
```
|
||||
sudo add-apt-repository ppa:xenatt/xenlism
|
||||
sudo apt update
|
||||
```
|
||||
|
||||
This PPA offers four packages:
|
||||
|
||||
* xenlism-finewalls: for a set of wallpapers that will be available directly in the wallpaper section of Ubuntu. One of the wallpapers has been used in the screenshot.
|
||||
|
||||
* xenlism-minimalism-theme: GTK theme
|
||||
|
||||
* xenlism-storm: an icon theme (see previous screenshots)
|
||||
|
||||
* xenlism-wildfire-icon-theme: another icon theme with several color variants (folder colors get changed in the variants)
|
||||
|
||||
You can decide on your own what theme component you want to install. Personally, I don’t see any harm in installing all the components.
|
||||
|
||||
```
|
||||
sudo apt install xenlism-minimalism-theme xenlism-storm-icon-theme xenlism-wildfire-icon-theme xenlism-finewalls
|
||||
```
|
||||
|
||||
You can use GNOME Tweaks for changing the theme and icons. If you are not familiar with the procedure already, I suggest reading this tutorial to learn [how to install themes in Ubuntu 18.04 GNOME][9].
|
||||
|
||||
### Getting Xenlism themes in other Linux distributions
|
||||
|
||||
You can install Xenlism themes on other Linux distributions as well. Installation instructions for various Linux distributions can be found on its website:
|
||||
|
||||
[Install Xenlism Themes][10]
|
||||
|
||||
### What do you think?
|
||||
|
||||
I know not everyone would agree with me but I loved this theme. I think you are going to see the glimpse of Xenlism theme in the screenshots in future tutorials on It’s FOSS.
|
||||
|
||||
Did you like Xenlism theme? If not, what theme do you like the most? Share your opinion in the comment section below.
|
||||
|
||||
#### 关于作者
|
||||
|
||||
I am a professional software developer, and founder of It's FOSS. I am an avid Linux lover and Open Source enthusiast. I use Ubuntu and believe in sharing knowledge. Apart from Linux, I love classic detective mysteries. I'm a huge fan of Agatha Christie's work.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://itsfoss.com/xenlism-theme/
|
||||
|
||||
作者：[Abhishek Prakash ][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://itsfoss.com/author/abhishek/
|
||||
[1]:https://itsfoss.com/author/abhishek/
|
||||
[2]:https://itsfoss.com/xenlism-theme/#comments
|
||||
[3]:https://itsfoss.com/category/desktop/
|
||||
[4]:https://itsfoss.com/tag/themes/
|
||||
[5]:https://itsfoss.com/tag/xenlism/
|
||||
[6]:https://itsfoss.com/best-gtk-themes/
|
||||
[7]:https://itsfoss.com/pop-icon-gtk-theme-ubuntu/
|
||||
[8]:https://itsfoss.com/best-icon-themes-ubuntu-16-04/
|
||||
[9]:https://itsfoss.com/install-themes-ubuntu/
|
||||
[10]:http://xenlism.github.io/minimalism/#install
|
||||
@ -1,3 +1,5 @@
|
||||
pinewall translating
|
||||
|
||||
A guide to Git branching
|
||||
======
|
||||
|
||||
|
||||
@ -1,57 +0,0 @@
|
||||
translating---geekpi
|
||||
|
||||
How to find your IP address in Linux
|
||||
======
|
||||
|
||||
Internet Protocol (IP) needs no introduction—we all use it daily. Even if you don't use it directly, when you type website-name.com on your web browser, it looks up the IP address of that URL and then loads the website.
|
||||
|
||||
Let's divide IP addresses into two categories: private and public. Private IP addresses are the ones your WiFi box (and company intranet) provide. They are in the range of 10.x.x.x, 172.16.x.x-172.31.x.x, and 192.168.x.x, where x=0 to 255. Public IP addresses, as the name suggests, are "public" and you can reach them from anywhere in the world. Every website has a unique IP address that can be reached by anyone and from anywhere; that is considered a public IP address.
|
||||
|
||||
Furthermore, there are two types of IP addresses: IPv4 and IPv6.
|
||||
|
||||
IPv4 addresses have the format x.x.x.x, where x=0 to 255. There are 2^32 (approximately 4 billion) possible IPv4 addresses.
|
||||
|
||||
IPv6 addresses have a more complex format using hex numbers. The total number of bits is 128, which means there are 2^128—340 undecillion!—possible IPv6 addresses. IPv6 was introduced to tackle the foreseeable exhaustion of IPv4 addresses in the near future.
|
||||
|
||||
As a network engineer, I recommend not sharing your machine’s public IP address with anyone. Your WiFi router has a public IP, which is the WAN (wide-area network) IP address, and it will be the same for any device connected to that WiFi. All the devices connected to the same WiFi have private IP addresses locally identified by the range provided above. For example, my laptop is connected with the IP address 192.168.0.5, and my phone is connected with 192.168.0.8. These are private IP addresses, but both would have the same public IP address.
|
||||
|
||||
The following commands will get you the IP address list to find public IP addresses for your machine:
|
||||
|
||||
1. `ifconfig.me`
|
||||
2. `curl -4/-6 icanhazip.com`
|
||||
3. `curl ipinfo.io/ip`
|
||||
4. `curl api.ipify.org`
|
||||
5. `curl checkip.dyndns.org`
|
||||
6. `dig +short myip.opendns.com @resolver1.opendns.com`
|
||||
7. `host myip.opendns.com resolver1.opendns.com`
|
||||
8. `curl ident.me`
|
||||
9. `curl bot.whatismyipaddress.com`
|
||||
10. `curl ipecho.net/plain`
|
||||
|
||||
|
||||
|
||||
The following commands will get you the private IP address of your interfaces:
|
||||
|
||||
1. `ifconfig -a`
|
||||
2. `ip addr (ip a)`
|
||||
3. `hostname -I | awk ‘{print $1}’`
|
||||
4. `ip route get 1.2.3.4 | awk '{print $7}'`
|
||||
5. `(Fedora) Wifi-Settings→ click the setting icon next to the Wifi name that you are connected to → Ipv4 and Ipv6 both can be seen`
|
||||
6. `nmcli -p device show`
|
||||
|
||||
|
||||
|
||||
_Note: Some utilities need to be installed on your system based on the Linux distro you are using. Also, some of the noted commands use a third-party website to get the IP_
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/5/how-find-ip-address-linux
|
||||
|
||||
作者：[Archit Modi][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://opensource.com/users/architmodi
|
||||
@ -0,0 +1,107 @@
|
||||
What You Need to Know About Cryptocurrency ‘Malware’ Found on Ubuntu’s Snap Store
|
||||
======
|
||||
Recently, it was discovered that a couple of apps in the Ubuntu Snaps store contained cryptocurrency mining software. Canonical swiftly removed the offending apps, but several questions are left unanswered.
|
||||
|
||||
### Discovery of Crypto Miner on Snap Store
|
||||
|
||||
![Crypto Miner Malware on Ubuntu Snap Store][1]
|
||||
|
||||
On May 11, a user named [tarwirdur][2] opened a new issue on the [snapcraft.io repository][3]. In the issue, he noted that a snap entitled 2048buntu created by Nicolas Tomb contained a cryptocurrency miner. He asked how he could “complain about the application” for security reasons. tarwirdur later posted to say that all the others snaps created by Nicolas Tomb also contained cryptocurrency miners.
|
||||
|
||||
It appears that the snaps used systemd to automatically launch the code at boot and run it in the background with the user none the wiser.
|
||||
|
||||
{For those unfamiliar with the terminology, a cryptocurrency miner is a piece of software that uses a computer’s main processor or graphics processor to “mine” digital currency. “Mining” usually involves solving a mathematical equation. In this case, if you were running the 2048buntu game, the game used additional processing power for cryptocurrency mining.}
|
||||
|
||||
The Snapcraft team responded by quickly removing all apps created by the offender. They also started an investigation.
|
||||
|
||||
### The Man Behind the Mask Speaks
|
||||
|
||||
On May 13, a Disqus user named Nicolas Tomb [posted a comment][4] on OMGUbuntu’s coverage of the news. In this comment, he stated that he added the cryptocurrency miner to monetize the snaps. He apologized for his actions and promised to send any funds that had been mined to the Ubuntu foundation.
|
||||
|
||||
We can’t say for sure if this comment was posted by the same Nicolas Tomb since the Disqus account was just recently created and only has one comment associated with it. For now, we’ll assume that it is.
|
||||
|
||||
### Canonical Makes a Statement
|
||||
|
||||
On May 15, Canonical issued a statement on the situation. Entitled [“Trust and security in the Snap Store”][5], the post starts out by restating the situation. They add that the snaps have been [reissued with the cryptocurrency mining code removed][6].
|
||||
|
||||
Canonical then attempts to examine the motives of Nicolas Tomb. They note that he told them he did it in an attempt to monetize the apps (as stated above) and stopped doing it when confronted. They also note that “mining cryptocurrency is not illegal or unethical by itself”. They are however unhappy about the fact that he did not disclose the cryptocurrency miner in the snap description.
|
||||
|
||||
From there Canonical moves to the subject of reviewing software. According to the post, the Snap Store uses a quality control system similar to iOS, Android, and Windows: “automated checkpoints that packages must go through before they are accepted, and manual reviews by a human when specific issues are flagged”.
|
||||
|
||||
However, Canonical says “it’s impossible for a large scale repository to only accept software after every individual file has been reviewed in detail”. Therefore, they need to trust the source, not the content. After all, that is what the current Ubuntu repo system is based on.
|
||||
|
||||
Canonical follows this up by talking about the future of snaps. They acknowledge that the current system is not perfect. They are continually working to improve it. They have “very interesting security features in the works that will improve the safety of the system and also the experience of people handling software deployments in servers and desktops”.
|
||||
|
||||
One of the features they are working on is the ability to see if a publisher is verified. Other improvements include: “upstreaming of all the AppArmor kernel patches” and other under-the-hood fixes.
|
||||
|
||||
### Thoughts on the ‘Snap store malware’
|
||||
|
||||
Based on all that I’ve read, I’ve got a few thoughts and questions of my own.
|
||||
|
||||
#### How Long Was This Running?
|
||||
|
||||
First of all, how long have these mining snaps been available on the Snap Store? Since they have all been removed, we don’t have that data. I was able to grab an image of the 2048buntu page from the Google cache, but it doesn’t show much of anything. Depending on how long it ran, how many systems it got installed on, and what cryptocurrency was being mined, we could either be talks about a little bit of money or a pile. A further question is: would Canonical have been able to catch this in the future?
|
||||
|
||||
#### Was it Really a Malware?
|
||||
|
||||
A lot of news sites are reporting this as a malware infection. I think I might have even seen this incident referred to as Linux’s first malware. I’m not sure that term is accurate. Dictionary.com defines [malware][7] as: “software intended to damage a computer, mobile device, computer system, or computer network, or to take partial control over its operation”.
|
||||
|
||||
The snaps in question did not damage or take control of the computers involved. it also did not infect other computers. It couldn’t have because all snaps are sandboxed. At the most, they leached processor power, that’s about it. So, I wouldn’t call it malware.
|
||||
|
||||
#### Nothing Like a Loophole
|
||||
|
||||
The one defense that Nicolas Tomb uses is that the Snap Store didn’t have any rules against cryptocurrency mining when he uploaded the snaps. {I can bet you that they are rectifying that problem right now.} They didn’t have that rule for the simple reason that no one had done it before. If Tomb was trying to do things correctly, he should have asked if this kind of behavior was allowed. The fact that he didn’t seems to point to the fact that he knew they would probably say no. At the very least, they would have told him to put it in the description.
|
||||
|
||||
![][8]
|
||||
|
||||
#### Something Looks Hinkey
|
||||
|
||||
As I said before, I got a screenshot of the 2048buntu page from Google cache. Just looking at it raises several red flags. First, there is almost no real description. This is all it says “Game like 2048. This game is clone popular game – 2048 with ubuntu colors.” Wow. {That’ll bring in the suckers.} When I read something as empty as that, I get nervous.
|
||||
|
||||
Another thing to notice is the size of it. Version 1.0 of the 2048buntu snap weighs almost 140 MB. Why would a game this simple need that much space? There are browser versions written in Javascript that probably use less than a quarter of that. There other snaps of 2048 games on the Snap Store and none of them has half the file size.
|
||||
|
||||
Then, you have the license. This is a clone of a popular game using Ubuntu colors. How can it be considered proprietary? I’m sure that legit devs in the audience would have uploaded it with a FOSS (Free and Open Source Software) license just because of the content.
|
||||
|
||||
These factors alone should have made this snap, in particular, stand out and call for a review.
|
||||
|
||||
#### Who is Nicolas Tomb?
|
||||
|
||||
After first reading about this, I decided to see what I could find out about the guy who started this mess. When I searched for Nicolas Tomb, I found nothing, zip, nada, zilch. All I found were a bunch of news articles about the cryptocurrency mining snaps and information about taking a trip to the tomb of St. Nicolas. There is no sign of Nicolas Tomb on Twitter or Github either. This seems like a name created just to upload these snaps.
|
||||
|
||||
This also leads to a point in the Canonical blog post about verifying publishers. The last time I looked, quite a few snaps were not published by the maintainers of the applications. This makes me nervous. I would be more willing to trust a snap of say Firefox if it was published by Mozilla, instead of Leonard Borsch. If it’s too much work for the application maintainer to also take care of the snap, there should be a way for the maintainer to put their stamp of approval on the snap for their program. Something like Firefox snap published by Fredrick Ham, approved by Mozilla Foundation. Just something to give the user more confidence in what they are downloading.
|
||||
|
||||
#### Snap Store Definitely has Room to Improve
|
||||
|
||||
It seems to me that one of the first features that the Snap Store team should have implemented was a way to report suspicious snaps. tarwirdur had to find the site’s Github page. The average user would not have thought of that. If the Snap Store can’t review every line of code, enabling the users to reports problems is the next best thing. Even rating system would not be a bad addition. I’m sure there would have been a couple people who would have given 2048buntu a low rating for using too many system resources.
|
||||
|
||||
#### Conclusion
|
||||
|
||||
From all the I have seen, I think that someone created a number of simple apps, embedded a cryptocurrency miner in each, and uploaded them to the Snap Store with the goal of raking in piles of money. Once they got caught, they claimed it was only to monetize the snaps. If that was true, they would have mentioned it in the snap description. Hidden crypto miners are nothing [new][9]. They are generally a method of computing power theft.
|
||||
|
||||
I wish that Canonical already have features in place to combat this problem and I hope they appear quickly.
|
||||
|
||||
What do you think of the Snap Store ‘malware episode’? What would you do to improve it? Let us know in the comments below.
|
||||
|
||||
If you found this article interesting, please take a minute to share it on social media.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://itsfoss.com/snapstore-cryptocurrency-saga/
|
||||
|
||||
作者：[John Paul][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://itsfoss.com/author/john/
|
||||
[1]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/05/ubuntu-snap-malware-800x450.jpeg
|
||||
[2]:https://github.com/tarwirdur
|
||||
[3]:https://github.com/canonical-websites/snapcraft.io/issues/651
|
||||
[4]:https://disqus.com/home/discussion/omgubuntu/malware_found_on_the_ubuntu_snap_store/#comment-3899153046
|
||||
[5]:https://blog.ubuntu.com/2018/05/15/trust-and-security-in-the-snap-store
|
||||
[6]:https://forum.snapcraft.io/t/action-against-snap-store-malware/5417/8
|
||||
[7]:http://www.dictionary.com/browse/malware?s=t
|
||||
[8]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/05/2048buntu.png
|
||||
[9]:https://krebsonsecurity.com/2018/03/who-and-what-is-coinhive/
|
||||
@ -1,3 +1,5 @@
|
||||
translating---geekpi
|
||||
|
||||
How To Install Ncurses Library In Linux
|
||||
======
|
||||
|
||||
|
||||
@ -0,0 +1,106 @@
|
||||
An introduction to cryptography and public key infrastructure
|
||||
======
|
||||
|
||||
|
||||
Secure communication is quickly becoming the norm for today's web. In July 2018, Google Chrome plans to [start showing "not secure" notifications][1] for **all** sites transmitted over HTTP (instead of HTTPS). Mozilla has a [similar plan][2]. While cryptography is becoming more commonplace, it has not become easier to understand. [Let's Encrypt][3] designed and built a wonderful solution to provide and periodically renew free security certificates, but if you don't understand the underlying concepts and pitfalls, you're just another member of a large group of [cargo cult][4] programmers.
|
||||
|
||||
### Attributes of secure communication
|
||||
|
||||
The intuitively obvious purpose of cryptography is confidentiality: a message can be transmitted without prying eyes learning its contents. For confidentiality, we encrypt a message: given a message, we pair it with a key and produce a meaningless jumble that can only be made useful again by reversing the process using the same key (thereby decrypting it). Suppose we have two friends, [Alice and Bob][5], and their nosy neighbor, Eve. Alice can encrypt a message like "Eve is annoying", send it to Bob, and never have to worry about Eve snooping on her.
|
||||
|
||||
For truly secure communication, we need more than confidentiality. Suppose Eve gathered enough of Alice and Bob's messages to figure out that the word "Eve" is encrypted as "Xyzzy". Furthermore, Eve knows Alice and Bob are planning a party and Alice will be sending Bob the guest list. If Eve intercepts the message and adds "Xyzzy" to the end of the list, she's managed to crash the party. Therefore, Alice and Bob need their communication to provide integrity: a message should be immune to tampering.
|
||||
|
||||
We have another problem though. Suppose Eve watches Bob open an envelope marked "From Alice" with a message inside from Alice reading "Buy another gallon of ice cream." Eve sees Bob go out and come back with ice cream, so she has a general idea of the message's contents even if the exact wording is unknown to her. Bob throws the message away, Eve recovers it, and then every day for the next week drops an envelope marked "From Alice" with a copy of the message in Bob's mailbox. Now the party has too much ice cream and Eve goes home with free ice cream when Bob gives it away at the end of the night. The extra messages are confidential, and their integrity is intact, but Bob has been misled as to the true identity of the sender. Authentication is the property of knowing that the person you are communicating with is in fact who they claim to be.
|
||||
|
||||
Information security has [other attributes][6], but confidentiality, integrity, and authentication are the three traits you must know.
|
||||
|
||||
### Encryption and ciphers
|
||||
|
||||
What are the components of encryption? We need a message which we'll call the plaintext. We may need to do some initial formatting to the message to make it suitable for the encryption process (padding it to a certain length if we're using a block cipher, for example). Then we take a secret sequence of bits called the key. A cipher then takes the key and transforms the plaintext into ciphertext. The ciphertext should look like random noise and only by using the same cipher and the same key (or as we will see later in the case of asymmetric ciphers, a mathematically related key) can the plaintext be restored.
|
||||
|
||||
The cipher transforms the plaintext's bits using the key's bits. Since we want to be able to decrypt the ciphertext, our cipher needs to be reversible too. We can use [XOR][7] as a simple example. It is reversible and is [its own inverse][8] (P ^ K = C; C ^ K = P) so it can both encrypt plaintext and decrypt ciphertext. A trivial use of an XOR can be used for encryption in a one-time pad, but it is generally not [practical][9]. However, it is possible to combine XOR with a function that generates an arbitrary stream of random data from a single key. Modern ciphers like AES and Chacha20 do exactly that.
|
||||
|
||||
We call any cipher that uses the same key to both encrypt and decrypt a symmetric cipher. Symmetric ciphers are divided into stream ciphers and block ciphers. A stream cipher runs through the message one bit or byte at a time. Our XOR cipher is a stream cipher, for example. Stream ciphers are useful if the length of the plaintext is unknown (such as data coming in from a pipe or socket). [RC4][10] is the best-known stream cipher but it is vulnerable to several different attacks, and the newest version (1.3) of the TLS protocol (the "S" in "HTTPS") does not even support it. [Efforts][11] are underway to create new stream ciphers with some candidates like [ChaCha20][12] already supported in TLS.
|
||||
|
||||
A block cipher takes a fix-sized block and encrypts it with a fixed-sized key. The current king of the hill in the block cipher world is the [Advanced Encryption Standard][13] (AES), and it has a block size of 128 bits. That's not very much data, so block ciphers have a [mode][14] that describes how to apply the cipher's block operation across a message of arbitrary size. The simplest mode is [Electronic Code Book][15] (ECB) which takes the message, splits it into blocks (padding the message's final block if necessary), and then encrypts each block with the key independently.
|
||||
|
||||
|
||||
|
||||
You may spot a problem here: if the same block appears multiple times in the message (a phrase like "GET / HTTP/1.1" in web traffic, for example) and we encrypt it using the same key, we'll get the same result. The appearance of a pattern in our encrypted communication makes it vulnerable to attack.
|
||||
|
||||
Thus there are more advanced modes such as [Cipher Block Chaining][16] (CBC) where the result of each block's encryption is XORed with the next block's plaintext. The very first block's plaintext is XORed with an initialization vector of random numbers. There are many other modes each with different advantages and disadvantages in security and speed. There are even modes, such as Counter (CTR), that can turn a block cipher into a stream cipher.
|
||||
|
||||
|
||||
|
||||
In contrast to symmetric ciphers, there are asymmetric ciphers (also called public-key cryptography). These ciphers use two keys: a public key and a private key. The keys are mathematically related but still distinct. Anything encrypted with the public key can only be decrypted with the private key and data encrypted with the private key can be decrypted with the public key. The public key is widely distributed while the private key is kept secret. If you want to communicate with a given person, you use their public key to encrypt your message and only their private key can decrypt it. [RSA][17] is the current heavyweight champion of asymmetric ciphers.
|
||||
|
||||
A major downside to asymmetric ciphers is that they are computationally expensive. Can we get authentication with symmetric ciphers to speed things up? If you only share a key with one other person, yes. But that breaks down quickly. Suppose a group of people want to communicate with one another using a symmetric cipher. The group members could establish keys for each unique pairing of members and encrypt messages based on the recipient, but a group of 20 people works out to 190 pairs of members total and 19 keys for each individual to manage and secure. By using an asymmetric cipher, each person only needs to guard their own private key and have access to a listing of public keys.
|
||||
|
||||
Asymmetric ciphers are also limited in the [amount of data][18] they can encrypt. Like block ciphers, you have to split a longer message into pieces. In practice then, asymmetric ciphers are often used to establish a confidential, authenticated channel which is then used to exchange a shared key for a symmetric cipher. The symmetric cipher is used for subsequent communications since it is much faster. TLS can operate in exactly this fashion.
|
||||
|
||||
### At the foundation
|
||||
|
||||
At the heart of secure communication are random numbers. Random numbers are used to generate keys and to provide unpredictability for otherwise deterministic processes. If the keys we use are predictable, then we're susceptible to attack right from the very start. Random numbers are difficult to generate on a computer which is meant to behave in a consistent manner. Computers can gather random data from things like mouse movement or keyboard timings. But gathering that randomness (called entropy) takes significant time and involve additional processing to ensure uniform distributions. It can even involve the use of dedicated hardware (such as [a wall of lava lamps][19]). Generally, once we have a truly random value, we use that as a seed to put into a [cryptographically secure pseudorandom number generator][20] Beginning with the same seed will always lead to the same stream of numbers, but what's important is that the stream of numbers descended from the seed don't exhibit any pattern. In the Linux kernel, [/dev/random and /dev/urandom][21], operate in this fashion: they gather entropy from multiple sources, process it to remove biases, create a seed, and can then provide the random numbers used to generate an RSA key for example.
|
||||
|
||||
### Other cryptographic building blocks
|
||||
|
||||
We've covered confidentiality, but I haven't mentioned integrity or authentication yet. For that, we'll need some new tools in our toolbox.
|
||||
|
||||
The first is the cryptographic hash function. A cryptographic hash function is meant to take an input of arbitrary size and produce a fixed size output (often called a digest). If we can find any two messages that create the same digest, that's a collision and makes the hash function unsuitable for cryptography. Note the emphasis on "find"; if we have an infinite world of messages and a fixed sized output, there are bound to be collisions, but if we can find any two messages that collide without a monumental investment of computational resources, that's a deal-breaker. Worse still would be if we could take a specific message and could then find another message that results in a collision.
|
||||
|
||||
As well, the hash function should be one-way: given a digest, it should be computationally infeasible to determine what the message is. Respectively, these [requirements][22] are called collision resistance, second preimage resistance, and preimage resistance. If we meet these requirements, our digest acts as a kind of fingerprint for a message. No two people ([in theory][23]) have the same fingerprints, and you can't take a fingerprint and turn it back into a person.
|
||||
|
||||
If we send a message and a digest, the recipient can use the same hash function to generate an independent digest. If the two digests match, they know the message hasn't been altered. [SHA-256][24] is the most popular cryptographic hash function currently since [SHA-1][25] is starting to [show its age][26].
|
||||
|
||||
Hashes sound great, but what good is sending a digest with a message if someone can tamper with your message and then tamper with the digest too? We need to mix hashing in with the ciphers we have. For symmetric ciphers, we have message authentication codes (MACs). MACs come in different forms, but an HMAC is based on hashing. An [HMAC][27] takes the key K and the message M and blends them together using a hashing function H with the formula H(K + H(K + M)) where "+" is concatenation. Why this formula specifically? That's beyond this article, but it has to do with protecting the integrity of the HMAC itself. The MAC is sent along with an encrypted message. Eve could blindly manipulate the message, but as soon as Bob independently calculates the MAC and compares it to the MAC he received, he'll realize the message has been tampered with.
|
||||
|
||||
For asymmetric ciphers, we have digital signatures. In RSA, encryption with a public key makes something only the private key can decrypt, but the inverse is true as well and can create a type of signature. If only I have the private key and encrypt a document, then only my public key will decrypt the document, and others can implicitly trust that I wrote it: authentication. In fact, we don't even need to encrypt the entire document. If we create a digest of the document, we can then encrypt just the fingerprint. Signing the digest instead of the whole document is faster and solves some problems around the size of a message that can be encrypted using asymmetric encryption. Recipients decrypt the digest, independently calculate the digest for the message, and then compare the two to ensure integrity. The method for digital signatures varies for other asymmetric ciphers, but the concept of using the public key to verify a signature remains.
|
||||
|
||||
### Putting it all together
|
||||
|
||||
Now that we have all the major pieces, we can implement a [system][28] that has all three of the attributes we're looking for. Alice picks a secret symmetric key and encrypts it with Bob's public key. Then she hashes the resulting ciphertext and uses her private key to sign the digest. Bob receives the ciphertext and the signature, computes the ciphertext's digest and compares it to the digest in the signature he verified using Alice's public key. If the two digests are identical, he knows the symmetric key has integrity and is authenticated. He decrypts the ciphertext with his private key and uses the symmetric key Alice sent him to communicate with her confidentially using HMACs with each message to ensure integrity. There's no protection here against a message being replayed (as seen in the ice cream disaster Eve caused). To handle that issue, we would need some sort of "handshake" that could be used to establish a random, short-lived session identifier.
|
||||
|
||||
The cryptographic world is vast and complex, but I hope this article gives you a basic mental model of the core goals and components it uses. With a solid foundation in the concepts, you'll be able to continue learning more.
|
||||
|
||||
Thank you to Hubert Kario, Florian Weimer, and Mike Bursell for their help with this article.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/5/cryptography-pki
|
||||
|
||||
作者：[Alex Wood][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://opensource.com/users/awood
|
||||
[1]:https://security.googleblog.com/2018/02/a-secure-web-is-here-to-stay.html
|
||||
[2]:https://blog.mozilla.org/security/2017/01/20/communicating-the-dangers-of-non-secure-http/
|
||||
[3]:https://letsencrypt.org/
|
||||
[4]:https://en.wikipedia.org/wiki/Cargo_cult_programming
|
||||
[5]:https://en.wikipedia.org/wiki/Alice_and_Bob
|
||||
[6]:https://en.wikipedia.org/wiki/Information_security#Availability
|
||||
[7]:https://en.wikipedia.org/wiki/XOR_cipher
|
||||
[8]:https://en.wikipedia.org/wiki/Involution_(mathematics)#Computer_science
|
||||
[9]:https://en.wikipedia.org/wiki/One-time_pad#Problems
|
||||
[10]:https://en.wikipedia.org/wiki/RC4
|
||||
[11]:https://en.wikipedia.org/wiki/ESTREAM
|
||||
[12]:https://en.wikipedia.org/wiki/Salsa20
|
||||
[13]:https://en.wikipedia.org/wiki/Advanced_Encryption_Standard
|
||||
[14]:https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation
|
||||
[15]:https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#/media/File:ECB_encryption.svg
|
||||
[16]:https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#/media/File:CBC_encryption.svg
|
||||
[17]:https://en.wikipedia.org/wiki/RSA_(cryptosystem)
|
||||
[18]:https://security.stackexchange.com/questions/33434/rsa-maximum-bytes-to-encrypt-comparison-to-aes-in-terms-of-security
|
||||
[19]:https://www.youtube.com/watch?v=1cUUfMeOijg
|
||||
[20]:https://en.wikipedia.org/wiki/Cryptographically_secure_pseudorandom_number_generator
|
||||
[21]:https://www.2uo.de/myths-about-urandom/
|
||||
[22]:https://crypto.stackexchange.com/a/1174
|
||||
[23]:https://www.telegraph.co.uk/science/2016/03/14/why-your-fingerprints-may-not-be-unique/
|
||||
[24]:https://en.wikipedia.org/wiki/SHA-2
|
||||
[25]:https://en.wikipedia.org/wiki/SHA-1
|
||||
[26]:https://security.googleblog.com/2017/02/announcing-first-sha1-collision.html
|
||||
[27]:https://en.wikipedia.org/wiki/HMAC
|
||||
[28]:https://en.wikipedia.org/wiki/Hybrid_cryptosystem
|
||||
@ -0,0 +1,53 @@
|
||||
Audacity quick tip: quickly remove background noise
|
||||
======
|
||||
|
||||
|
||||
When recording sounds on a laptop — say for a simple first screencast — many users typically use the built-in microphone. However, these small microphones also capture a lot of background noise. In this quick tip, learn how to use [Audacity][1] in Fedora to quickly remove the background noise from audio files.
|
||||
|
||||
### Installing Audacity
|
||||
|
||||
Audacity is an application in Fedora for mixing, cutting, and editing audio files. It supports a wide range of formats out of the box on Fedora — including MP3 and OGG. Install Audacity from the Software application.
|
||||
|
||||
![][2]
|
||||
|
||||
If the terminal is more your speed, use the command:
|
||||
```
|
||||
sudo dnf install audacity
|
||||
|
||||
```
|
||||
|
||||
### Import your Audio, sample background noise
|
||||
|
||||
After installing Audacity, open the application, and import your sound using the **File > Import** menu item. This example uses a [sound bite from freesound.org][3] to which noise was added:
|
||||
|
||||
Next, take a sample of the background noise to be filtered out. With the tracks imported, select an area of the track that contains only the background noise. Then choose **Effect > Noise Reduction** from the menu, and press the **Get Noise Profile** button.
|
||||
|
||||
![][4]
|
||||
|
||||
### Filter the Noise
|
||||
|
||||
Next, select the area of the track you want to filter the noise from. Do this either by selecting with the mouse, or **Ctrl + a** to select the entire track. Finally, open the **Effect > Noise Reduction** dialog again, and click OK to apply the filter.
|
||||
|
||||
![][5]
|
||||
|
||||
Additionally, play around with the settings until your tracks sound better. Here is the original file again, followed by the noise reduced track for comparison (using the default settings):
|
||||
|
||||
https://ryanlerch.fedorapeople.org/sidebyside.ogg?_=2
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://fedoramagazine.org/audacity-quick-tip-quickly-remove-background-noise/
|
||||
|
||||
作者：[Ryan Lerch][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://fedoramagazine.org/introducing-flatpak/
|
||||
[1]:https://www.audacityteam.org/
|
||||
[2]:https://fedoramagazine.org/wp-content/uploads/2018/03/audacity-software.jpg
|
||||
[3]:https://freesound.org/people/levinj/sounds/8323/
|
||||
[4]:https://fedoramagazine.org/wp-content/uploads/2018/03/select-noise-profile.gif
|
||||
[5]:https://fedoramagazine.org/wp-content/uploads/2018/03/apply-filter.gif
|
||||
@ -0,0 +1,209 @@
|
||||
How to Install and Configure KVM on Ubuntu 18.04 LTS Server
|
||||
======
|
||||
**KVM** (Kernel-based Virtual Machine) is an open source full virtualization solution for Linux like systems, KVM provides virtualization functionality using the virtualization extensions like **Intel VT** or **AMD-V**. Whenever we install KVM on any linux box then it turns it into the hyervisor by loading the kernel modules like **kvm-intel.ko** ( for intel based machines) and **kvm-amd.ko** ( for amd based machines).
|
||||
|
||||
KVM allows us to install and run multiple virtual machines (Windows & Linux). We can create and manage KVM based virtual machines either via **virt-manager** graphical user interface or **virt-install** & **virsh** cli commands.
|
||||
|
||||
In this article we will discuss how to install and configure **KVM hypervisor** on Ubuntu 18.04 LTS server. I am assuming you have already installed Ubuntu 18.04 LTS server on your system. Login to your server and perform the following steps.
|
||||
|
||||
### Step:1 Verify Whether your system support hardware virtualization
|
||||
|
||||
Execute below egrep command to verify whether your system supports hardware virtualization or not,
|
||||
```
|
||||
linuxtechi@kvm-ubuntu18-04:~$ egrep -c '(vmx|svm)' /proc/cpuinfo
|
||||
1
|
||||
linuxtechi@kvm-ubuntu18-04:~$
|
||||
|
||||
```
|
||||
|
||||
If the output is greater than 0 then it means your system supports Virtualization else reboot your system, then go to BIOS settings and enable VT technology.
|
||||
|
||||
Now Install “ **kvm-ok** ” utility using below command, it is used to determine if your server is capable of running hardware accelerated KVM virtual machines
|
||||
```
|
||||
linuxtechi@kvm-ubuntu18-04:~$ sudo apt install cpu-checker
|
||||
|
||||
```
|
||||
|
||||
Run kvm-ok command and verify the output,
|
||||
```
|
||||
linuxtechi@kvm-ubuntu18-04:~$ sudo kvm-ok
|
||||
INFO: /dev/kvm exists
|
||||
KVM acceleration can be used
|
||||
linuxtechi@kvm-ubuntu18-04:~$
|
||||
|
||||
```
|
||||
|
||||
### Step:2 Install KVM and its required packages
|
||||
|
||||
Run the below apt commands to install KVM and its dependencies
|
||||
```
|
||||
linuxtechi@kvm-ubuntu18-04:~$ sudo apt update
|
||||
linuxtechi@kvm-ubuntu18-04:~$ sudo apt install qemu qemu-kvm libvirt-bin bridge-utils virt-manager
|
||||
|
||||
```
|
||||
|
||||
Once the above packages are installed successfully, then your local user (In my case linuxtechi) will be added to the group libvirtd automatically.
|
||||
|
||||
### Step:3 Start & enable libvirtd service
|
||||
|
||||
Whenever we install qemu & libvirtd packages in Ubuntu 18.04 Server then it will automatically start and enable libvirtd service, In case libvirtd service is not started and enabled then run beneath commands,
|
||||
```
|
||||
linuxtechi@kvm-ubuntu18-04:~$ sudo service libvirtd start
|
||||
linuxtechi@kvm-ubuntu18-04:~$ sudo update-rc.d libvirtd enable
|
||||
|
||||
```
|
||||
|
||||
Now verify the status of libvirtd service using below command,
|
||||
```
|
||||
linuxtechi@kvm-ubuntu18-04:~$ service libvirtd status
|
||||
|
||||
```
|
||||
|
||||
Output would be something like below:
|
||||
|
||||
[![libvirtd-command-ubuntu18-04][1]![libvirtd-command-ubuntu18-04][2]][3]
|
||||
|
||||
### Step:4 Configure Network Bridge for KVM virtual Machines
|
||||
|
||||
Network bridge is required to access the KVM based virtual machines outside the KVM hypervisor or host. In Ubuntu 18.04, network is managed by netplan utility, whenever we freshly installed Ubuntu 18.04 server then a file with name “ **/etc/netplan/50-cloud-init.yaml** ” is created automatically, to configure static IP and bridge, netplan utility will refer this file.
|
||||
|
||||
As of now I have already configured the static IP via this file and content of this file is below:
|
||||
```
|
||||
network:
|
||||
ethernets:
|
||||
ens33:
|
||||
addresses: [192.168.0.51/24]
|
||||
gateway4: 192.168.0.1
|
||||
nameservers:
|
||||
addresses: [192.168.0.1]
|
||||
dhcp4: no
|
||||
optional: true
|
||||
version: 2
|
||||
|
||||
```
|
||||
|
||||
Let’s add the network bridge definition in this file,
|
||||
```
|
||||
linuxtechi@kvm-ubuntu18-04:~$ sudo vi /etc/netplan/50-cloud-init.yaml
|
||||
|
||||
network:
|
||||
version: 2
|
||||
ethernets:
|
||||
ens33:
|
||||
dhcp4: no
|
||||
dhcp6: no
|
||||
|
||||
bridges:
|
||||
br0:
|
||||
interfaces: [ens33]
|
||||
dhcp4: no
|
||||
addresses: [192.168.0.51/24]
|
||||
gateway4: 192.168.0.1
|
||||
nameservers:
|
||||
addresses: [192.168.0.1]
|
||||
|
||||
```
|
||||
|
||||
As you can see we have removed the IP address from interface(ens33) and add the same IP to the bridge ‘ **br0** ‘ and also added interface (ens33) to the bridge br0. Apply these changes using below netplan command,
|
||||
```
|
||||
linuxtechi@kvm-ubuntu18-04:~$ sudo netplan apply
|
||||
linuxtechi@kvm-ubuntu18-04:~$
|
||||
|
||||
```
|
||||
|
||||
If you want to see the debug logs then use the below command,
|
||||
```
|
||||
linuxtechi@kvm-ubuntu18-04:~$ sudo netplan --debug apply
|
||||
|
||||
```
|
||||
|
||||
Now Verify the bridge status using following methods:
|
||||
```
|
||||
linuxtechi@kvm-ubuntu18-04:~$ sudo networkctl status -a
|
||||
|
||||
```
|
||||
|
||||
[![networkctl-command-output-ubuntu18-04][1]![networkctl-command-output-ubuntu18-04][4]][4]
|
||||
```
|
||||
linuxtechi@kvm-ubuntu18-04:~$ ifconfig
|
||||
|
||||
```
|
||||
|
||||
[![ifconfig-command-output-ubuntu18-04][1]![ifconfig-command-output-ubuntu18-04][5]][5]
|
||||
|
||||
### Start:5 Creating Virtual machine (virt-manager or virt-install command )
|
||||
|
||||
There are two ways to create virtual machine:
|
||||
|
||||
* virt-manager (GUI utility)
|
||||
* virt-install command (cli utility)
|
||||
|
||||
|
||||
|
||||
**Creating Virtual machine using virt-manager:**
|
||||
|
||||
Start the virt-manager by executing the beneath command,
|
||||
```
|
||||
linuxtechi@kvm-ubuntu18-04:~$ sudo virt-manager
|
||||
|
||||
```
|
||||
|
||||
[![Start-Virt-Manager-Ubuntu18-04][1]![Start-Virt-Manager-Ubuntu18-04][6]][6]
|
||||
|
||||
Create a new virtual machine
|
||||
|
||||
[![ISO-file-Virt-Manager][1]![ISO-file-Virt-Manager][7]][7]
|
||||
|
||||
Click on forward and select the ISO file, in my case I am using RHEL 7.3 iso file.
|
||||
|
||||
[![Select-ISO-file-virt-manager-Ubuntu18-04-Server][1]![Select-ISO-file-virt-manager-Ubuntu18-04-Server][8]][8]
|
||||
|
||||
Click on Forward
|
||||
|
||||
In the next couple of windows, you will be prompted to specify the RAM, CPU and disk for the VM.
|
||||
|
||||
Now Specify the Name of the Virtual Machine and network,
|
||||
|
||||
[![VM-Name-Network-Virt-Manager-Ubuntu18-04][1]![VM-Name-Network-Virt-Manager-Ubuntu18-04][9]][9]
|
||||
|
||||
Click on Finish
|
||||
|
||||
[![RHEL7-3-Installation-Virt-Manager][1]![RHEL7-3-Installation-Virt-Manager][10]][10]
|
||||
|
||||
Now follow the screen instruction and complete the installation,
|
||||
|
||||
**Creating Virtual machine from CLI using virt-install command,**
|
||||
|
||||
Use the below virt-install command to create a VM from terminal, it will start the installation in CLI, replace the name of the VM, description, location of ISO file and network bridge as per your setup.
|
||||
```
|
||||
linuxtechi@kvm-ubuntu18-04:~$ sudo virt-install -n DB-Server --description "Test VM for Database" --os-type=Linux --os-variant=rhel7 --ram=1096 --vcpus=1 --disk path=/var/lib/libvirt/images/dbserver.img,bus=virtio,size=10 --network bridge:br0 --graphics none --location /home/linuxtechi/rhel-server-7.3-x86_64-dvd.iso --extra-args console=ttyS0
|
||||
|
||||
```
|
||||
|
||||
That’s conclude the article, I hope this article help you to install KVM on your Ubuntu 18.04 Server. Apart from this, KVM is the default hypervisor for Openstack.
|
||||
|
||||
Read More On : “[ **How to Create, Revert and Delete KVM Virtual machine (domain) snapshot with virsh command**][11]“
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.linuxtechi.com/install-configure-kvm-ubuntu-18-04-server/
|
||||
|
||||
作者：[Pradeep Kumar][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://www.linuxtechi.com/author/pradeep/
|
||||
[1]:https://www.linuxtechi.com/wp-content/plugins/lazy-load/images/1x1.trans.gif
|
||||
[2]:https://www.linuxtechi.com/wp-content/uploads/2018/05/libvirtd-command-ubuntu18-04-1024x339.jpg
|
||||
[3]:https://www.linuxtechi.com/wp-content/uploads/2018/05/libvirtd-command-ubuntu18-04.jpg
|
||||
[4]:https://www.linuxtechi.com/wp-content/uploads/2018/05/networkctl-command-output-ubuntu18-04.jpg
|
||||
[5]:https://www.linuxtechi.com/wp-content/uploads/2018/05/ifconfig-command-output-ubuntu18-04.jpg
|
||||
[6]:https://www.linuxtechi.com/wp-content/uploads/2018/05/Start-Virt-Manager-Ubuntu18-04.jpg
|
||||
[7]:https://www.linuxtechi.com/wp-content/uploads/2018/05/ISO-file-Virt-Manager.jpg
|
||||
[8]:https://www.linuxtechi.com/wp-content/uploads/2018/05/Select-ISO-file-virt-manager-Ubuntu18-04-Server.jpg
|
||||
[9]:https://www.linuxtechi.com/wp-content/uploads/2018/05/VM-Name-Network-Virt-Manager-Ubuntu18-04.jpg
|
||||
[10]:https://www.linuxtechi.com/wp-content/uploads/2018/05/RHEL7-3-Installation-Virt-Manager.jpg
|
||||
[11]:https://www.linuxtechi.com/create-revert-delete-kvm-virtual-machine-snapshot-virsh-command/
|
||||
@ -0,0 +1,117 @@
|
||||
Advanced use of the less text file viewer in Linux
|
||||
======
|
||||
|
||||
|
||||
|
||||
I recently read Scott Nesbitt's article "[Using less to view text files at the Linux command line][1]" and was inspired to share additional tips and tricks I use with `less`.
|
||||
|
||||
### LESS env var
|
||||
|
||||
If you have an environment variable `LESS` defined (e.g., in your `.bashrc`), `less` treats it as a list of options, as if passed on the command line.
|
||||
|
||||
I use this:
|
||||
```
|
||||
LESS='-C -M -I -j 10 -# 4'
|
||||
|
||||
```
|
||||
|
||||
These mean:
|
||||
|
||||
* `-C` – Make full-screen reprints faster by not scrolling from the bottom.
|
||||
* `-M` – Show more information from the last (status) line. You can customize the information shown with `-PM`, but I usually do not bother.
|
||||
* `-I` – Ignore letter case (upper/lower) in searches.
|
||||
* `-j 10` – Show search results in line 10 of the terminal, instead of the first line. This way you have 10 lines of context each time you press `n` (or `N`) to jump to the next (or previous) match.
|
||||
* `-# 4` – Jump four characters to the right or left when pressing the Right or Left arrow key. The default is to jump half of the screen, which I usually find to be too much. Generally speaking, `less` seems to be (at least partially) optimized to the environment it was initially developed in, with slow modems and low-bandwidth internet connections, when it made sense to jump half a screen.
|
||||
|
||||
|
||||
|
||||
### PAGER env var
|
||||
|
||||
Many programs show information using the command set in the `PAGER` environment variable (if it's set). So, you can set `PAGER=less` in your `.bashrc` and have your program run `less`. Check the man page environ(7) (`man 7 environ`) for other such variables.
|
||||
|
||||
### -S
|
||||
|
||||
`-S` tells `less` to chop long lines instead of wrapping them. I rarely find a need for this unless (and until) I've started viewing a file. Fortunately, you can type all command-line options inside `less` as if they were keyboard commands. So, if I want to chop long lines while I'm already in a file, I can simply type `-S`.
|
||||
|
||||
The command-line optiontellsto chop long lines instead of wrapping them. I rarely find a need for this unless (and until) I've started viewing a file. Fortunately, you can type all command-line options insideas if they were keyboard commands. So, if I want to chop long lines while I'm already in a file, I can simply type
|
||||
|
||||
Here's an example I use a lot:
|
||||
```
|
||||
su - postgres
|
||||
|
||||
export PAGER=less # Because I didn't bother editing postgres' .bashrc on all the machines I use it on
|
||||
|
||||
psql
|
||||
|
||||
```
|
||||
|
||||
Sometimes when I later view the output of a `SELECT` command with a very wide output, I type `-S` so it will be formatted nicely. If it jumps too far when I press the Right arrow to see more (because I didn't set `-#`), I can type `-#8`, then each Right arrow press will move eight characters to the right.
|
||||
|
||||
Sometimes after typing `-S` too many times, I exit psql and run it again after entering:
|
||||
```
|
||||
export LESS=-S
|
||||
|
||||
```
|
||||
|
||||
### F
|
||||
|
||||
The command `F` makes `less` work like `tail -f`—waiting until more data is added to the file before showing it. One advantage this has over `tail -f` is that highlighting search matches still works. So you can enter `less /var/log/logfile`, search for something—which will highlight all occurrences of it (unless you used `-g`)—and then press `F`. When more data is written to the log, `less` will show it and highlight the new matches.
|
||||
|
||||
After you press `F`, you can press `Ctrl+C` to stop it from looking for new data (this will not kill it); go back into the file to see older stuff, search for other things, etc.; and then press `F` again to look at more new data.
|
||||
|
||||
### Searching
|
||||
|
||||
Searches use the system's regexp library, and this usually means you can use extended regular expressions. In particular, searching for `one|two|three` will find and highlight all occurrences of one, two, or three.
|
||||
|
||||
Another pattern I use a lot, especially with wide log lines (e.g., ones that span more than one terminal line), is `.*something.*`, which highlights the entire line. This pattern makes it much easier to see where a line starts and finishes. I also combine these, such as: `.*one thing.*|.*another thing.*`, or `key: .*|.*marker.*` to see the contents of `key` (e.g., in a log file with a dump of some dictionary/hash) and highlight relevant marker lines (so I have a context), or even, if I know the value is surrounded by quotes:
|
||||
```
|
||||
key: '[^']*'|.*marker.*
|
||||
|
||||
```
|
||||
|
||||
`less` maintains a history of your search items and saves them to disk for future invocations. When you press `/` (or `?`), you can go through this history with the Up or Down arrow (as well as do basic line editing).
|
||||
|
||||
I stumbled upon what seems to be a very useful feature when skimming through the `less` man page while writing this article: skipping uninteresting lines with `&!pattern`. For example, while looking for something in `/var/log/messages`, I used to iterate through this list of commands:
|
||||
```
|
||||
cat /var/log/messages | egrep -v 'systemd: Started Session' | less
|
||||
|
||||
cat /var/log/messages | egrep -v 'systemd: Started Session|systemd: Starting Session' | less
|
||||
|
||||
cat /var/log/messages | egrep -v 'systemd: Started Session|systemd: Starting Session|User Slice' | less
|
||||
|
||||
cat /var/log/messages | egrep -v 'systemd: Started Session|systemd: Starting Session|User Slice|dbus' | less
|
||||
|
||||
cat /var/log/messages | egrep -v 'systemd: Started Session|systemd: Starting Session|User Slice|dbus|PackageKit Daemon' | less
|
||||
|
||||
```
|
||||
|
||||
But now I know how to do the same thing within `less`. For example, I can type `&!systemd: Started Session`, then decide I want to get rid of `systemd: Starting Session`, so I add it by typing `&!` and use the Up arrow to get the previous search from the history. Then I type `|systemd: Starting Session` and press `Enter`, continuing to add more items the same way until I filter out enough to see the more interesting stuff.
|
||||
|
||||
### =
|
||||
|
||||
The command `=` shows more information about the file and location, even more than `-M`. If the file is very long, and calculating `=` takes too long, you can press `Ctrl+C` and it will stop trying.
|
||||
|
||||
If the content you're viewing is from a pipe rather than a file, `=` (and `-M`) will not show what it does not know, including the number of lines and bytes in the file. To see that data, if you know that `command` will finish quickly, you can jump to the end with `G`, and then `less` will start showing that information.
|
||||
|
||||
If you press `G` and the command writing to the pipe takes longer than expected, you can press `Ctrl+C`, and the command will be killed. Pressing `Ctrl+C` will kill it even if you didn't press `G`, so be careful not to press `Ctrl+C` accidentally if you don't intend to kill it. For this reason, if the command does something (that is, it's not only showing information), it's usually safer to write its output to a file and view the file in a separate terminal, instead of using a pipe.
|
||||
|
||||
### Why you need less
|
||||
|
||||
`less` is a very powerful program, and contrary to newer contenders in this space, such as `most` and `moar`, you are likely to find it on almost all the systems you use, just like `vi`. So, even if you use GUI viewers or editors, it's worth investing some time going through the `less` man page, at least to get a feeling of what's available. This way, when you need to do something that might be covered by existing functionality, you'll know to search the manual page or the internet to find what you need.
|
||||
|
||||
For more information, visit the [less home page][2]. The site has a nice FAQ with more tips and tricks.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/5/advanced-use-less-text-file-viewer
|
||||
|
||||
作者：[Yedidyah Bar David][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://opensource.com/users/didib
|
||||
[1]:http://opensource.com/article/18/4/using-less-view-text-files-command-line
|
||||
[2]:http://www.greenwoodsoftware.com/less/
|
||||
@ -0,0 +1,83 @@
|
||||
Free Resources for Securing Your Open Source Code
|
||||
======
|
||||
|
||||
|
||||
|
||||
While the widespread adoption of open source continues at a healthy rate, the recent [2018 Open Source Security and Risk Analysis Report][1] from Black Duck and Synopsys reveals some common concerns and highlights the need for sound security practices. The report examines findings from the anonymized data of over 1,100 commercial codebases with represented Industries from automotive, Big Data, enterprise software, financial services, healthcare, IoT, manufacturing, and more.
|
||||
|
||||
The report highlights a massive uptick in open source adoption, with 96 percent of the applications scanned containing open source components. However, the report also includes warnings about existing vulnerabilities. Among the [findings][2]:
|
||||
|
||||
* “What is worrisome is that 78 percent of the codebases examined contained at least one open source vulnerability, with an average 64 vulnerabilities per codebase.”
|
||||
|
||||
* “Over 54 percent of the vulnerabilities found in audited codebases are considered high-risk vulnerabilities.”
|
||||
|
||||
* Seventeen percent of the codebases contained a highly publicized vulnerability such as Heartbleed, Logjam, Freak, Drown, or Poodle.
|
||||
|
||||
|
||||
|
||||
|
||||
"The report clearly demonstrates that with the growth in open source use, organizations need to ensure they have the tools to detect vulnerabilities in open source components and manage whatever license compliance their use of open source may require," said Tim Mackey, technical evangelist at Black Duck by Synopsys.
|
||||
|
||||
Indeed, with ever more impactful security threats emerging,the need for fluency with security tools and practices has never been more pronounced. Most organizations are aware that network administrators and sysadmins need to have strong security skills, and, in many cases security certifications. [In this article,][3] we explored some of the tools, certifications and practices that many of them wisely embrace.
|
||||
|
||||
The Linux Foundation has also made available many informational and educational resources on security. Likewise, the Linux community offers many free resources for specific platforms and tools. For example, The Linux Foundation has published a [Linux workstation security checklist][4] that covers a lot of good ground. Online publications ranging from the [Fedora security guide][5] to the[Securing Debian Manual][6] can also help users protect against vulnerabilities within specific platforms.
|
||||
|
||||
The widespread use of cloud platforms such as OpenStack is also stepping up the need for cloud-centric security smarts. According to The Linux Foundation’s[Guide to the Open Cloud][7]: “Security is still a top concern among companies considering moving workloads to the public cloud, according to Gartner, despite a strong track record of security and increased transparency from cloud providers. Rather, security is still an issue largely due to companies’ inexperience and improper use of cloud services.”
|
||||
|
||||
For both organizations and individuals, the smallest holes in implementation of routers, firewalls, VPNs, and virtual machines can leave room for big security problems. Here is a collection of free tools that can plug these kinds of holes:
|
||||
|
||||
* [Wireshark][8], a packet analyzer
|
||||
|
||||
* [KeePass Password Safe][9], a free open source password manager
|
||||
|
||||
* [Malwarebytes][10], a free anti-malware and antivirus tool
|
||||
|
||||
* [NMAP][11], a powerful security scanner
|
||||
|
||||
* [NIKTO][12], an open source web server scanner
|
||||
|
||||
* [Ansible][13], a tool for automating secure IT provisioning
|
||||
|
||||
* [Metasploit][14], a tool for understanding attack vectors and doing penetration testing
|
||||
|
||||
|
||||
|
||||
|
||||
Instructional videos abound for these tools. You’ll find a whole[tutorial series][15] for Metasploit, and [video tutorials][16] for Wireshark. Quite a few free ebooks provide good guidance on security as well. For example, one of the common ways for security threats to invade open source platforms occurs in M&A scenarios, where technology platforms are merged—often without proper open source audits. In an ebook titled [Open Source Audits in Merger and Acquisition Transactions][17], from Ibrahim Haddad and The Linux Foundation, you’ll find an overview of the open source audit process and important considerations for code compliance, preparation, and documentation.
|
||||
|
||||
Meanwhile, we’ve[previously covered][18] a free ebook from the editors at[The New Stack][19] called Networking, Security & Storage with Docker & Containers. It covers the latest approaches to secure container networking, as well as native efforts by Docker to create efficient and secure networking practices. The ebook is loaded with best practices for locking down security at scale.
|
||||
|
||||
All of these tools and resources, and many more, can go a long way toward preventing security problems, and an ounce of prevention is, as they say, worth a pound of cure. With security breaches continuing, now is an excellent time to look into the many security and compliance resources for open source tools and platforms available. Learn more about security, compliance, and open source project health [here][20].
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.linux.com/blog/2018/5/free-resources-securing-your-open-source-code
|
||||
|
||||
作者：[Sam Dean][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://www.linux.com/users/sam-dean
|
||||
[1]:https://www.blackducksoftware.com/open-source-security-risk-analysis-2018
|
||||
[2]:https://www.prnewswire.com/news-releases/synopsys-report-finds-majority-of-software-plagued-by-known-vulnerabilities-and-license-conflicts-as-open-source-adoption-soars-300648367.html
|
||||
[3]:https://www.linux.com/blog/sysadmin-ebook/2017/8/future-proof-your-sysadmin-career-locking-down-security
|
||||
[4]:http://go.linuxfoundation.org/ebook_workstation_security
|
||||
[5]:https://docs.fedoraproject.org/en-US/Fedora/19/html/Security_Guide/index.html
|
||||
[6]:https://www.debian.org/doc/manuals/securing-debian-howto/index.en.html
|
||||
[7]:https://www.linux.com/publications/2016-guide-open-cloud
|
||||
[8]:https://www.wireshark.org/
|
||||
[9]:http://keepass.info/
|
||||
[10]:https://www.malwarebytes.com/
|
||||
[11]:http://searchsecurity.techtarget.co.uk/tip/Nmap-tutorial-Nmap-scan-examples-for-vulnerability-discovery
|
||||
[12]:https://cirt.net/Nikto2
|
||||
[13]:https://www.ansible.com/
|
||||
[14]:https://www.metasploit.com/
|
||||
[15]:http://www.computerweekly.com/tutorial/The-Metasploit-Framework-Tutorial-PDF-compendium-Your-ready-reckoner
|
||||
[16]:https://www.youtube.com/watch?v=TkCSr30UojM
|
||||
[17]:https://www.linuxfoundation.org/resources/open-source-audits-merger-acquisition-transactions/
|
||||
[18]:https://www.linux.com/news/networking-security-storage-docker-containers-free-ebook-covers-essentials
|
||||
[19]:http://thenewstack.io/ebookseries/
|
||||
[20]:https://www.linuxfoundation.org/projects/security-compliance/
|
||||
@ -0,0 +1,102 @@
|
||||
How to Enable Click to Minimize On Ubuntu
|
||||
============================================================
|
||||
|
||||
|
||||
_Brief: This quick tutorial shows you how to enable click to minimize option on Ubuntu 18.04 and Ubuntu 16.04._
|
||||
|
||||
The launcher at the left hand side in [Ubuntu][7] is a handy tool for quickly accessing applications. When you click on an icon in the launcher, the application window appears in focus.
|
||||
|
||||
If you click again on the icon of an application already in focus, the default behavior is to do nothing. This may bother you if you expect the application window to be minimized on the second click.
|
||||
|
||||
Perhaps this GIF will be better in explaining the click on minimize behavior on Ubuntu.
|
||||
|
||||
[video](https://giphy.com/gifs/linux-ubuntu-itsfoss-52FlrSIMxnZ1qq9koP?utm_source=iframe&utm_medium=embed&utm_campaign=Embeds&utm_term=https%3A%2F%2Fitsfoss.com%2Fclick-to-minimize-ubuntu%2F%3Futm_source%3Dnewsletter&%3Butm_medium=email&%3Butm_campaign=new_linux_laptop_ubuntu_1804_flavor_reviews_meltdown_20_and_other_linux_stuff&%3Butm_term=2018-05-23)
|
||||
|
||||
In my opinion, this should be the default behavior but apparently Ubuntu doesn’t think so. So what? Customization is one of the main reason [why I use Linux][8] and this behavior can also be easily changed.
|
||||
|
||||
In this quick tutorial, I’ll show you how to enable click to minimize on Ubuntu 18.04 and 16.04\. I’ll show both command line and the GUI methods here.
|
||||
|
||||
|
||||
### Enable click to minimize on Ubuntu using command line (recommended)
|
||||
|
||||
_This method is for Ubuntu 18.04 and 17.10 users with [GNOME desktop environment][1]_ .
|
||||
|
||||
The first option is using the terminal. I recommend this way to ‘minimize on click’ even if you are not comfortable with the command line.
|
||||
|
||||
It’s not at all complicated. Open a terminal using Ctrl+Alt+T shortcut or searching for it in the menu. All you need is to copy paste the command below in the terminal.
|
||||
|
||||
```
|
||||
gsettings set org.gnome.shell.extensions.dash-to-dock click-action 'minimize'
|
||||
```
|
||||
|
||||
No need of restarting your system or any thing of that sort. You can test the minimize on click behavior immediately after it.
|
||||
|
||||
If you do not like ‘click to minimize’ behavior, you can set it back to default using the command below:
|
||||
|
||||
```
|
||||
gsettings reset org.gnome.shell.extensions.dash-to-dock click-action
|
||||
```
|
||||
|
||||
### Enable click to minimize on Ubuntu using GUI tool
|
||||
|
||||
You can do the same steps mentioned above using a GUI tool called [Dconf Editor][10]. It is a powerful tool that allows you to change many hidden aspects of your Linux desktop. I avoid recommending it because one wrong click here and there may screw up your desktop settings. So be careful while using this tool keeping in mind that it works on single click and changes are applied immediately.
|
||||
|
||||
You can find and install Dconf Editor in the Ubuntu Software Center.
|
||||
|
||||
|
||||
|
||||
Once installed, launch Dconf Editor and go to org -> gnome -> shell -> extensions -> dash-to-dock. Scroll down a bit until you find click-action. Click on it to access the click action settings.
|
||||
|
||||
In here, turn off the Use default value option and change the Custom Valueto ‘minimize’.
|
||||
|
||||
|
||||
|
||||
You can see that the minimize on click behavior has been applied instantly.
|
||||
|
||||
### Enable click to minimize on Ubuntu 16.04 Unity
|
||||
|
||||
If you are using Unity desktop environment, you can easily d it using Unity Tweak Tool. If you have not installed it already, look for Unity Tweak Tool in Software Center and install it.
|
||||
|
||||
Once installed, launch Unity Tweak Tool and click on Launcher here.
|
||||
|
||||
|
||||
|
||||
Check the “Minimize single window application on click” option here.
|
||||
|
||||
|
||||
|
||||
That’s all. The change takes into effect right away.
|
||||
|
||||
### Did it work for you?
|
||||
|
||||
I hope this quick tip helped you to enable the minimize on click feature in Ubuntu. If you are using Ubuntu 18.04, I suggest reading [GNOME customization tips][11] for more such options.
|
||||
|
||||
If you have any questions or suggestions, please leave a comment. If it helped you, perhaps you could share this article on various social media platforms such as Reddit and Twitter.
|
||||
|
||||
|
||||
#### 关于作者
|
||||
|
||||
I am a professional software developer, and founder of It's FOSS. I am an avid Linux lover and Open Source enthusiast. I use Ubuntu and believe in sharing knowledge. Apart from Linux, I love classic detective mysteries. I'm a huge fan of Agatha Christie's work.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://itsfoss.com/click-to-minimize-ubuntu/
|
||||
|
||||
作者：[Abhishek Prakash ][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://itsfoss.com/author/abhishek/
|
||||
[1]:https://www.gnome.org/
|
||||
[2]:https://itsfoss.com/author/abhishek/
|
||||
[3]:https://itsfoss.com/click-to-minimize-ubuntu/#comments
|
||||
[4]:https://itsfoss.com/category/how-to/
|
||||
[5]:https://itsfoss.com/tag/quick-tip/
|
||||
[6]:https://itsfoss.com/tag/ubuntu-18-04/
|
||||
[7]:https://www.ubuntu.com/
|
||||
[8]:https://itsfoss.com/reasons-switch-linux-windows-xp/
|
||||
[9]:https://itsfoss.com/how-to-know-ubuntu-unity-version/
|
||||
[10]:https://wiki.gnome.org/Projects/dconf
|
||||
[11]:https://itsfoss.com/gnome-tricks-ubuntu/
|
||||
232
sources/tech/20180522 How to Run Your Own Git Server.md
Normal file
232
sources/tech/20180522 How to Run Your Own Git Server.md
Normal file
@ -0,0 +1,232 @@
|
||||
How to Run Your Own Git Server
|
||||
======
|
||||
**Learn how to set up your own Git server in this tutorial from our archives.**
|
||||
|
||||
[Git ][1]is a versioning system [developed by Linus Torvalds][2], that is used by millions of users around the globe. Companies like GitHub offer code hosting services based on Git. [According to reports, GitHub, a code hosting site, is the world's largest code hosting service.][3] The company claims that there are 9.2M people collaborating right now across 21.8M repositories on GitHub. Big companies are now moving to GitHub. [Even Google, the search engine giant, is shutting it's own Google Code and moving to GitHub.][4]
|
||||
|
||||
### Run your own Git server
|
||||
|
||||
GitHub is a great service, however there are some limitations and restrictions, especially if you are an individual or a small player. One of the limitations of GitHub is that the free service doesn’t allow private hosting of the code. [You have to pay a monthly fee of $7 to host 5 private repositories][5], and the expenses go up with more repos.
|
||||
|
||||
In cases like these or when you want more control, the best path is to run Git on your own server. Not only do you save costs, you also have more control over your server. In most cases a majority of advanced Linux users already have their own servers and pushing Git on those servers is like ‘free as in beer’.
|
||||
|
||||
In this tutorial we are going to talk about two methods of managing your code on your own server. One is running a bare, basic Git server and and the second one is via a GUI tool called [GitLab][6]. For this tutorial I used a fully patched Ubuntu 14.04 LTS server running on a VPS.
|
||||
|
||||
### Install Git on your server
|
||||
|
||||
In this tutorial we are considering a use-case where we have a remote server and a local server and we will work between these machines. For the sake of simplicity we will call them remote-server and local-server.
|
||||
|
||||
First, install Git on both machines. You can install Git from the packages already available via the repos or your distros, or you can do it manually. In this article we will use the simpler method:
|
||||
```
|
||||
sudo apt-get install git-core
|
||||
|
||||
```
|
||||
|
||||
Then add a user for Git.
|
||||
```
|
||||
sudo useradd git
|
||||
passwd git
|
||||
|
||||
```
|
||||
|
||||
In order to ease access to the server let's set-up a password-less ssh login. First create ssh keys on your local machine:
|
||||
```
|
||||
ssh-keygen -t rsa
|
||||
|
||||
```
|
||||
|
||||
It will ask you to provide the location for storing the key, just hit Enter to use the default location. The second question will be to provide it with a pass phrase which will be needed to access the remote server. It generates two keys - a public key and a private key. Note down the location of the public key which you will need in the next step.
|
||||
|
||||
Now you have to copy these keys to the server so that the two machines can talk to each other. Run the following command on your local machine:
|
||||
```
|
||||
cat ~/.ssh/id_rsa.pub | ssh git@remote-server "mkdir -p ~/.ssh && cat >> ~/.ssh/authorized_keys"
|
||||
|
||||
```
|
||||
|
||||
Now ssh into the server and create a project directory for Git. You can use the desired path for the repo.
|
||||
|
||||
Then change to this directory:
|
||||
```
|
||||
cd /home/swapnil/project-1.git
|
||||
|
||||
```
|
||||
|
||||
Then create an empty repo:
|
||||
```
|
||||
git init --bare
|
||||
Initialized empty Git repository in /home/swapnil/project-1.git
|
||||
|
||||
```
|
||||
|
||||
We now need to create a Git repo on the local machine.
|
||||
```
|
||||
mkdir -p /home/swapnil/git/project
|
||||
|
||||
```
|
||||
|
||||
And change to this directory:
|
||||
```
|
||||
cd /home/swapnil/git/project
|
||||
|
||||
```
|
||||
|
||||
Now create the files that you need for the project in this directory. Stay in this directory and initiate git:
|
||||
```
|
||||
git init
|
||||
Initialized empty Git repository in /home/swapnil/git/project
|
||||
|
||||
```
|
||||
|
||||
Now add files to the repo:
|
||||
```
|
||||
git add .
|
||||
|
||||
```
|
||||
|
||||
Now every time you add a file or make changes you have to run the add command above. You also need to write a commit message with every change in a file. The commit message basically tells what changes were made.
|
||||
```
|
||||
git commit -m "message" -a
|
||||
[master (root-commit) 57331ee] message
|
||||
2 files changed, 2 insertions(+)
|
||||
create mode 100644 GoT.txt
|
||||
create mode 100644 writing.txt
|
||||
|
||||
```
|
||||
|
||||
In this case I had a file called GoT (Game of Thrones review) and I made some changes, so when I ran the command it specified that changes were made to the file. In the above command '-a' option means commits for all files in the repo. If you made changes to only one you can specify the name of that file instead of using '-a'.
|
||||
|
||||
An example:
|
||||
```
|
||||
git commit -m "message" GoT.txt
|
||||
[master e517b10] message
|
||||
1 file changed, 1 insertion(+)
|
||||
|
||||
```
|
||||
|
||||
Until now we have been working on the local server. Now we have to push these changes to the server so the work is accessible over the Internet and you can collaborate with other team members.
|
||||
```
|
||||
git remote add origin ssh://git@remote-server/repo-<wbr< a="">>path-on-server..git
|
||||
|
||||
```
|
||||
|
||||
Now you can push or pull changes between the server and local machine using the 'push' or 'pull' option:
|
||||
```
|
||||
git push origin master
|
||||
|
||||
```
|
||||
|
||||
If there are other team members who want to work with the project they need to clone the repo on the server to their local machine:
|
||||
```
|
||||
git clone git@remote-server:/home/swapnil/project.git
|
||||
|
||||
```
|
||||
|
||||
Here /home/swapnil/project.git is the project path on the remote server, exchange the values for your own server.
|
||||
|
||||
Then change directory on the local machine (exchange project with the name of project on your server):
|
||||
```
|
||||
cd /project
|
||||
|
||||
```
|
||||
|
||||
Now they can edit files, write commit change messages and then push them to the server:
|
||||
```
|
||||
git commit -m 'corrections in GoT.txt story' -a
|
||||
And then push changes:
|
||||
|
||||
git push origin master
|
||||
|
||||
```
|
||||
|
||||
I assume this is enough for a new user to get started with Git on their own servers. If you are looking for some GUI tools to manage changes on local machines, you can use GUI tools such as QGit or GitK for Linux.
|
||||
|
||||
### Using GitLab
|
||||
|
||||
This was a pure command line solution for project owner and collaborator. It's certainly not as easy as using GitHub. Unfortunately, while GitHub is the world's largest code hosting service; its own software is not available for others to use. It's not open source so you can't grab the source code and compile your own GitHub. Unlike WordPress or Drupal you can't download GitHub and run it on your own servers.
|
||||
|
||||
As usual in the open source world there is no end to the options. GitLab is a nifty project which does exactly that. It's an open source project which allows users to run a project management system similar to GitHub on their own servers.
|
||||
|
||||
You can use GitLab to run a service similar to GitHub for your team members or your company. You can use GitLab to work on private projects before releasing them for public contributions.
|
||||
|
||||
GitLab employs the traditional Open Source business model. They have two products: free of cost open source software, which users can install on their own servers, and a hosted service similar to GitHub.
|
||||
|
||||
The downloadable version has two editions - the free of cost community edition and the paid enterprise edition. The enterprise edition is based on the community edition but comes with additional features targeted at enterprise customers. It’s more or less similar to what WordPress.org or Wordpress.com offer.
|
||||
|
||||
The community edition is highly scalable and can support 25,000 users on a single server or cluster. Some of the features of GitLab include: Git repository management, code reviews, issue tracking, activity feeds, and wikis. It comes with GitLab CI for continuous integration and delivery.
|
||||
|
||||
Many VPS providers such as Digital Ocean offer GitLab droplets for users. If you want to run it on your own server, you can install it manually. GitLab offers an Omnibus package for different operating systems. Before we install GitLab, you may want to configure an SMTP email server so that GitLab can push emails as and when needed. They recommend Postfix. So, install Postfix on your server:
|
||||
```
|
||||
sudo apt-get install postfix
|
||||
|
||||
```
|
||||
|
||||
During installation of Postfix it will ask you some questions; don't skip them. If you did miss it you can always re-configure it using this command:
|
||||
```
|
||||
sudo dpkg-reconfigure postfix
|
||||
|
||||
```
|
||||
|
||||
When you run this command choose "Internet Site" and provide the email ID for the domain which will be used by Gitlab.
|
||||
|
||||
In my case I provided it with:
|
||||
```
|
||||
This e-mail address is being protected from spambots. You need JavaScript enabled to view it
|
||||
|
||||
|
||||
```
|
||||
|
||||
Use Tab and create a username for postfix. The Next page will ask you to provide a destination for mail.
|
||||
|
||||
In the rest of the steps, use the default options. Once Postfix is installed and configured, let's move on to install GitLab.
|
||||
|
||||
Download the packages using wget (replace the download link with the [latest packages from here][7]) :
|
||||
```
|
||||
wget https://downloads-packages.s3.amazonaws.com/ubuntu-14.04/gitlab_7.9.4-omnibus.1-1_amd64.deb
|
||||
|
||||
```
|
||||
|
||||
Then install the package:
|
||||
```
|
||||
sudo dpkg -i gitlab_7.9.4-omnibus.1-1_amd64.deb
|
||||
|
||||
```
|
||||
|
||||
Now it's time to configure and start GitLabs.
|
||||
```
|
||||
sudo gitlab-ctl reconfigure
|
||||
|
||||
```
|
||||
|
||||
You now need to configure the domain name in the configuration file so you can access GitLab. Open the file.
|
||||
```
|
||||
nano /etc/gitlab/gitlab.rb
|
||||
|
||||
```
|
||||
|
||||
In this file edit the 'external_url' and give the server domain. Save the file and then open the newly created GitLab site from a web browser.
|
||||
|
||||
By default it creates 'root' as the system admin and uses '5iveL!fe' as the password. Log into the GitLab site and then change the password.
|
||||
|
||||
Once the password is changed, log into the site and start managing your project.
|
||||
|
||||
GitLab is overflowing with features and options. I will borrow popular lines from the movie, The Matrix: "Unfortunately, no one can be told what all GitLab can do. You have to try it for yourself."
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.linux.com/learn/how-run-your-own-git-server
|
||||
|
||||
作者：[Swapnil Bhartiya][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://www.linux.com/users/arnieswap
|
||||
[1]:https://github.com/git/git
|
||||
[2]:https://www.linuxfoundation.org/blog/10-years-of-git-an-interview-with-git-creator-linus-torvalds/
|
||||
[3]:https://github.com/about/press
|
||||
[4]:http://google-opensource.blogspot.com/2015/03/farewell-to-google-code.html
|
||||
[5]:https://github.com/pricing
|
||||
[6]:https://about.gitlab.com/
|
||||
[7]:https://about.gitlab.com/downloads/
|
||||
@ -0,0 +1,134 @@
|
||||
Using Stratis to manage Linux storage from the command line
|
||||
======
|
||||
|
||||
|
||||
|
||||
As discussed in [Part 1][1] and [Part 2][2] of this series, Stratis is a volume-managing filesystem with functionality similar to that of [ZFS][3] and [Btrfs][4]. In this article, we'll walk through how to use Stratis on the command line.
|
||||
|
||||
### Getting Stratis
|
||||
|
||||
For non-developers, the easiest way to try Stratis now is in [Fedora 28][5].
|
||||
|
||||
Once you're running this, you can install the Stratis daemon and the Stratis command-line tool with:
|
||||
```
|
||||
# dnf install stratis-cli stratisd
|
||||
|
||||
```
|
||||
|
||||
### Creating a pool
|
||||
|
||||
Stratis has three concepts: blockdevs, pools, and filesystems. Blockdevs are the block devices, such as a disk or a disk partition, that make up a pool. Once a pool is created, filesystems can be created from it.
|
||||
|
||||
Assuming you have a block device called `vdg` on your system that is not currently in use or mounted, you can create a Stratis pool on it with:
|
||||
```
|
||||
# stratis pool create mypool /dev/vdg
|
||||
|
||||
```
|
||||
|
||||
This assumes `vdg` is completely zeroed and empty. If it is not in use but has old data on it, it may be necessary to use `pool create`'s `- force` option. If it is in use, don't use it for Stratis.
|
||||
|
||||
If you want to create a pool from more than one block device, just list them all on the `pool create` command line. You can also add more blockdevs later using the `blockdev add-data` command. Note that Stratis requires blockdevs to be at least 1 GiB in size.
|
||||
|
||||
### Creating filesystems
|
||||
|
||||
Once you've created a pool called `mypool`, you can create filesystems from it:
|
||||
```
|
||||
# stratis fs create mypool myfs1
|
||||
|
||||
```
|
||||
|
||||
After creating a filesystem called `myfs1` from pool `mypool`, you can mount and use it, using the entries Stratis has created within /dev/stratis:
|
||||
```
|
||||
# mkdir myfs1
|
||||
|
||||
# mount /dev/stratis/mypool/myfs1 myfs1
|
||||
|
||||
```
|
||||
|
||||
The filesystem is now mounted on `myfs1` and ready to use.
|
||||
|
||||
### Snapshots
|
||||
|
||||
In addition to creating empty filesystems, you can also create a filesystem as a snapshot of an existing filesystem:
|
||||
```
|
||||
# stratis fs snapshot mypool myfs1 myfs1-experiment
|
||||
|
||||
```
|
||||
|
||||
After doing so, you could mount the new `myfs1-experiment`, which will initially contain the same file contents as `myfs1`, but could change as the filesystem is modified. Whatever changes you made to `myfs1-experiment` would not be reflected in `myfs1` unless you unmounted `myfs1` and destroyed it with:
|
||||
```
|
||||
# umount myfs1
|
||||
|
||||
# stratis fs destroy mypool myfs1
|
||||
|
||||
```
|
||||
|
||||
and then snapshotted the snapshot to recreate it and remounted it:
|
||||
```
|
||||
# stratis fs snapshot mypool myfs1-experiment myfs1
|
||||
|
||||
# mount /dev/stratis/mypool/myfs1 myfs1
|
||||
|
||||
```
|
||||
|
||||
### Getting information
|
||||
|
||||
Stratis can list pools on the system:
|
||||
```
|
||||
# stratis pool list
|
||||
|
||||
```
|
||||
|
||||
As filesystems have more data written to them, you will see the "Total Physical Used" value increase. Be careful when this approaches "Total Physical Size"; we're still working on handling this correctly.
|
||||
|
||||
To list filesystems within a pool:
|
||||
```
|
||||
# stratis fs list mypool
|
||||
|
||||
```
|
||||
|
||||
To list the blockdevs that make up a pool:
|
||||
```
|
||||
# stratis blockdev list mypool
|
||||
|
||||
```
|
||||
|
||||
These give only minimal information currently, but they will provide more in the future.
|
||||
|
||||
#### Destroying a pool
|
||||
|
||||
Once you have an idea of what Stratis can do, to destroy the pool, first make sure all filesystems created from it are unmounted and destroyed, then use the `pool destroy` command:
|
||||
```
|
||||
# umount myfs1
|
||||
|
||||
# umount myfs1-experiment (if you created it)
|
||||
|
||||
# stratis fs destroy mypool myfs1
|
||||
|
||||
# stratis fs destroy mypool myfs1-experiment
|
||||
|
||||
# stratis pool destroy mypool
|
||||
|
||||
```
|
||||
|
||||
`stratis pool list` should now show no pools.
|
||||
|
||||
That's it! For more information, please see the manpage: `man stratis`.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/5/stratis-storage-linux-command-line
|
||||
|
||||
作者：[Andy Grover][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://opensource.com/users/agrover
|
||||
[1]:https://opensource.com/article/18/4/stratis-easy-use-local-storage-management-linux
|
||||
[2]:https://opensource.com/article/18/4/stratis-lessons-learned
|
||||
[3]:https://en.wikipedia.org/wiki/ZFS
|
||||
[4]:https://en.wikipedia.org/wiki/Btrfs
|
||||
[5]:https://fedoraproject.org/wiki/Releases/28/Schedule
|
||||
@ -0,0 +1,69 @@
|
||||
KevinSJ translating
|
||||
|
||||
How CERN Is Using Linux and Open Source
|
||||
============================================================
|
||||
|
||||
|
||||
>CERN relies on open source technology to handle huge amounts of data generated by the Large Hadron Collider. The ATLAS (shown here) is a general-purpose detector that probes for fundamental particles. (Image courtesy: CERN)[Used with permission][2]
|
||||
|
||||
[CERN][3]
|
||||
|
||||
[CERN][6] really needs no introduction. Among other things, the European Organization for Nuclear Research created the World Wide Web and the Large Hadron Collider (LHC), the world’s largest particle accelerator, which was used in discovery of the [Higgs boson][7]. Tim Bell, who is responsible for the organization’s IT Operating Systems and Infrastructure group, says the goal of his team is “to provide the compute facility for 13,000 physicists around the world to analyze those collisions, understand what the universe is made of and how it works.”
|
||||
|
||||
CERN is conducting hardcore science, especially with the LHC, which [generates massive amounts of data][8] when it’s operational. “CERN currently stores about 200 petabytes of data, with over 10 petabytes of data coming in each month when the accelerator is running. This certainly produces extreme challenges for the computing infrastructure, regarding storing this large amount of data, as well as the having the capability to process it in a reasonable timeframe. It puts pressure on the networking and storage technologies and the ability to deliver an efficient compute framework,” Bell said.
|
||||
|
||||
### [tim-bell-cern.png][4]
|
||||
|
||||
|
||||
Tim Bell, CERN[Used with permission][1]Swapnil Bhartiya
|
||||
|
||||
The scale at which LHC operates and the amount of data it generates pose some serious challenges. But CERN is not new to such problems. Founded in 1954, CERN has been around for about 60 years. “We've always been facing computing challenges that are difficult problems to solve, but we have been working with open source communities to solve them,” Bell said. “Even in the 90s, when we invented the World Wide Web, we were looking to share this with the rest of humanity in order to be able to benefit from the research done at CERN and open source was the right vehicle to do that.”
|
||||
|
||||
### Using OpenStack and CentOS
|
||||
|
||||
Today, CERN is a heavy user of OpenStack, and Bell is one of the Board Members of the OpenStack Foundation. But CERN predates OpenStack. For several years, they have been using various open source technologies to deliver services through Linux servers.
|
||||
|
||||
“Over the past 10 years, we've found that rather than taking our problems ourselves, we find upstream open source communities with which we can work, who are facing similar challenges and then we contribute to those projects rather than inventing everything ourselves and then having to maintain it as well,” said Bell.
|
||||
|
||||
A good example is Linux itself. CERN used to be a Red Hat Enterprise Linux customer. But, back in 2004, they worked with Fermilab to build their own Linux distribution called [Scientific Linux][9]. Eventually they realized that, because they were not modifying the kernel, there was no point in spending time spinning up their own distribution; so they migrated to CentOS. Because CentOS is a fully open source and community driven project, CERN could collaborate with the project and contribute to how CentOS is built and distributed.
|
||||
|
||||
CERN helps CentOS with infrastructure and they also organize CentOS DoJo at CERN where engineers can get together to improve the CentOS packaging.
|
||||
|
||||
In addition to OpenStack and CentOS, CERN is a heavy user of other open source projects, including Puppet for configuration management, Grafana and influxDB for monitoring, and is involved in many more.
|
||||
|
||||
“We collaborate with around 170 labs around the world. So every time that we find an improvement in an open source project, other labs can easily take that and use it,” said Bell, “At the same time, we also learn from others. When large scale installations like eBay and Rackspace make changes to improve scalability of solutions, it benefits us and allows us to scale.”
|
||||
|
||||
### Solving realistic problems
|
||||
|
||||
Around 2012, CERN was looking at ways to scale computing for the LHC, but the challenge was people rather than technology. The number of staff that CERN employs is fixed. “We had to find ways in which we can scale the compute without requiring a large number of additional people in order to administer that,” Bell said. “OpenStack provided us with an automated API-driven, software-defined infrastructure.” OpenStack also allowed CERN to look at problems related to the delivery of services and then automate those, without having to scale the staff.
|
||||
|
||||
“We're currently running about 280,000 cores and 7,000 servers across two data centers in Geneva and in Budapest. We are using software-defined infrastructure to automate everything, which allows us to continue to add additional servers while remaining within the same envelope of staff,” said Bell.
|
||||
|
||||
As time progresses, CERN will be dealing with even bigger challenges. Large Hadron Collider has a roadmap out to 2035, including a number of significant upgrades. “We run the accelerator for three to four years and then have a period of 18 months or two years when we upgrade the infrastructure. This maintenance period allows us to also do some computing planning,” said Bell. CERN is also planning High Luminosity Large Hadron Collider upgrade, which will allow for beams with higher luminosity. The upgrade would mean about 60 times more compute requirement compared to what CERN has today.
|
||||
|
||||
“With Moore's Law, we will maybe get one quarter of the way there, so we have to find ways under which we can be scaling the compute and the storage infrastructure correspondingly and finding automation and solutions such as OpenStack will help that,” said Bell.
|
||||
|
||||
“When we started off the large Hadron collider and looked at how we would deliver the computing, it was clear that we couldn't put everything into the data center at CERN, so we devised a distributed grid structure, with tier zero at CERN and then a cascading structure around that,” said Bell. “There are around 12 large tier one centers and then 150 small universities and labs around the world. They receive samples at the data from the LHC in order to assist the physicists to understand and analyze the data.”
|
||||
|
||||
That structure means CERN is collaborating internationally, with hundreds of countries contributing toward the analysis of that data. It boils down to the fundamental principle that open source is not just about sharing code, it’s about collaboration among people to share knowledge and achieve what no single individual, organization, or company can achieve alone. That’s the Higgs boson of the open source world.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.linux.com/blog/2018/5/how-cern-using-linux-open-source
|
||||
|
||||
作者：[SWAPNIL BHARTIYA ][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://www.linux.com/users/arnieswap
|
||||
[1]:https://www.linux.com/licenses/category/used-permission
|
||||
[2]:https://www.linux.com/licenses/category/used-permission
|
||||
[3]:https://home.cern/about/experiments/atlas
|
||||
[4]:https://www.linux.com/files/images/tim-bell-cernpng
|
||||
[5]:https://www.linux.com/files/images/atlas-cernjpg
|
||||
[6]:https://home.cern/
|
||||
[7]:https://home.cern/topics/higgs-boson
|
||||
[8]:https://home.cern/about/computing
|
||||
[9]:https://www.scientificlinux.org/
|
||||
@ -0,0 +1,130 @@
|
||||
IT自动化的下一步是什么: 6 大趋势
|
||||
======
|
||||
|
||||
|
||||
|
||||
我们最近介绍了 [促进自动化的因素][1] ,目前正在被人们采用的 [趋势][2], 以及那些刚开始使用自动化部分流程组织 [有用的技巧][3] 。
|
||||
|
||||
噢, 我们也分享了在你的公司[如何使用自动化的案例][4] , 以及 [长期成功的关键][5].
|
||||
|
||||
现在, 只有一个问题: 自动化的下一步是什么? 我们邀请一系列专家分享一下 [自动化][6]不远的将来。 以下是他们建议IT领域领导需密切关注的六大趋势。
|
||||
|
||||
### 1. 机器学习的成熟
|
||||
|
||||
对于关于 [机器学习][7]的讨论 (与“自我学习系统”相似的定义),对于绝大多数组织的项目来说，实际执行起来它仍然为时过早。但预计这将发生变化，机器学习将在下一次IT自动化浪潮中将扮演着至关重要的角色。
|
||||
|
||||
[Advanced Systems Concepts, Inc.][8]公司工程总监 Mehul Amin 指出机器学习是IT自动化下一个关键增长领域之一。
|
||||
|
||||
“随着数据化的发展, 自动化软件理应可以自我决策，否则这就是开发人员的责任了”， Amin 说。 “例如, 开发者需要执行构建内容, 但是识别系统最佳执行流程的，可能是由系统内软件分析完成。”
|
||||
|
||||
假设将这个系统延伸到其他地方中。Amin 指出，机器学习可以使自动化系统在必要的时候提供额外的资源，以需要满足时间线或SLA，同样在不需要资源的时候退出以及其他的可能性。
|
||||
|
||||
显然不只有 Amin 一个人这样认为。
|
||||
|
||||
[Sungard Availability Services][9] 公司首席架构师 Kiran Chitturi 表示,“IT自动化正在走向自我学习的方向” 。“系统将会能测试和监控自己，加强业务流程和软件交付能力。”
|
||||
|
||||
Chitturi 指出自动化测试就是个例子。脚本测试已经被广泛采用，但很快这些自动化测试流程将会更容易学习，更快发展，例如开发出新的代码或将更为广泛地影响生产环境。
|
||||
|
||||
### 2. 人工智能催生的自动化
|
||||
|
||||
上述原则同样适合 [人工智能][10]（但是为独立）的领域。假定新兴的人工智能技术将也会产生新的自动化机会。根据对人工智能的定义，机器学习在短时间内可能会对IT领域产生巨大的影响（并且我们可能会看到这两个领域的许多重叠的定义和理解）。
|
||||
|
||||
[SolarWinds][11]公司技术负责人 Patrick Hubbard说，“人工智能（AI）和机器学习的整合普遍被认为对未来几年的商业成功起至关重要的作用。”
|
||||
|
||||
### 3. 这并不意味着不再需要人力
|
||||
|
||||
让我们试着安慰一下那些不知所措的人：前两种趋势并不一定意味着我们将失去工作。
|
||||
|
||||
这很可能意味着各种角色的改变以及[全新角色][12]的创造。
|
||||
|
||||
但是在可预见的将来，至少，你不必需要机器人鞠躬。
|
||||
|
||||
“一台机器只能运行在给定的环境变量中它不能选择包含新的变量，在今天只有人类可以这样做，” Hubbard 解释说。“但是，对于IT专业人员来说，这将是需要培养AI和自动化技能的时代。如对程序设计、编程、管理人工智能和机器学习功能算法的基本理解，以及用强大的安全状态面对更复杂的网络攻击。”
|
||||
|
||||
Hubbard 分享一些新的工具或功能例子，例如支持人工智能的安全软件或机器学习的应用程序，这些应用程序可以远程发现石油管道中的维护需求。两者都可以提高效益和效果，自然不会代替需要信息安全或管道维护的人员。
|
||||
|
||||
“许多新功能仍需要人工监控，”Hubbard 说。“例如，为了让机器确定一些‘预测’是否可能成为‘规律’，人为的管理是必要的。”
|
||||
|
||||
即使你把机器学习和AI先放在一边，看待一般地IT自动化，同样原理也是成立的,尤其是在软件开发生命周期中。
|
||||
|
||||
[Juniper Networks][13]公司自动化首席架构师 Matthew Oswalt ，指出IT自动化增长的根本原因是它通过减少操作基础设施所需的人工工作量来创造直接价值。
|
||||
|
||||
在代码上，操作工程师可以使用事件驱动的自动化提前定义他们的工作流程，而不是在凌晨3点来应对基础设施的问题。
|
||||
|
||||
“它也将操作工作流程作为代码而不再是容易过时的文档或系统知识阶段，”Oswalt解释说。“操作人员仍然需要在[自动化]工具响应事件方面后发挥积极作用。采用自动化的下一个阶段是建立一个能够跨IT频谱识别发生的有趣事件的系统，并以自主方式进行响应。在代码上，操作工程师可以使用事件驱动的自动化提前定义他们的工作流程，而不是在凌晨3点来应对基础设施的问题。他们可以依靠这个系统在任何时候以同样的方式作出回应。”
|
||||
|
||||
### 4. 对自动化的焦虑将会减少
|
||||
|
||||
SolarWinds公司的 Hubbard 指出，“自动化”一词本身就产生大量的不确定性和担忧，不仅仅是在IT领域，而且是跨专业领域，他说这种担忧是合理的。但一些随之而来的担忧可能被夸大了，甚至是科技产业本身。现实可能实际上是这方面的镇静力：当自动化的实际实施和实践帮助人们认识到这个列表中的“3”时，我们将看到“4”的出现。
|
||||
|
||||
“今年我们可能会看到对自动化焦虑的减少，更多的组织开始接受人工智能和机器学习作为增加现有人力资源的一种方式，”Hubbard说。“自动化历史上的今天为更多的工作创造了空间,通过降低成本和时间来完成较小任务，并将劳动力重新集中到无法自动化并需要人力的事情上。人工智能和机器学习也是如此。”
|
||||
|
||||
自动化还将减少IT领导者神经紧张主题的一些焦虑：安全。正如[红帽][14]公司首席架构师 Matt Smith 最近[指出][15]的那样，自动化将越来越多地帮助IT部门降低与维护任务相关的安全风险。
|
||||
|
||||
他的建议是：“首先在维护活动期间记录和自动化IT资产之间的交互。通过依靠自动化，您不仅可以消除历史上需要大量手动操作和手术技巧的任务，还可以降低人为错误的风险，并展示当您的IT组织采纳变更和新工作方法时可能发生的情况。最终，这将迅速减少对应用安全补丁的抵制。而且它还可以帮助您的企业在下一次重大安全事件中摆脱头条新闻。”
|
||||
|
||||
**[ 阅读全文: [12个企业安全坏习惯要打破。][16] ] **
|
||||
|
||||
### 5. 脚本和自动化工具将持续发展
|
||||
|
||||
看到许多组织增加自动化的第一步 - 通常以脚本或自动化工具（有时称为配置管理工具）的形式 - 作为“早期”工作。
|
||||
|
||||
但是随着各种自动化技术的使用，对这些工具的观点也在不断发展。
|
||||
|
||||
[DataVision][18]首席运营官 Mark Abolafia 表示：“数据中心环境中存在很多重复性过程，容易出现人为错误，[Ansible][17]等技术有助于缓解这些问题。“通过 Ansible ，人们可以为一组操作编写特定的步骤，并输入不同的变量，例如地址等，使过去长时间的过程链实现自动化，而这些过程以前都需要人为触摸和更长的交货时间。”
|
||||
|
||||
**[想了解更多关于Ansible这个方面的知识吗？阅读相关文章:[使用Ansible时的成功秘诀][19]。 ]**
|
||||
|
||||
另一个因素是：工具本身将继续变得更先进。
|
||||
|
||||
“使用先进的IT自动化工具，开发人员将能够在更短的时间内构建和自动化工作流程，减少易出错的编码，” ASCI 公司的 Amin 说。“这些工具包括预先构建的，预先测试过的拖放式集成，API作业，丰富的变量使用，参考功能和对象修订历史记录。”
|
||||
|
||||
### 6. 自动化开创了新的指标机会
|
||||
|
||||
正如我们在此前所说的那样，IT自动化不是万能的。它不会修复被破坏的流程，或者以其他方式为您的组织提供全面的灵丹妙药。这也是持续不断的：自动化并不排除衡量性能的必要性。
|
||||
|
||||
**[ 参见我们的相关文章 [DevOps指标：你在衡量什么重要吗？][20] ]**
|
||||
|
||||
实际上,自动化应该打开新的机会。
|
||||
|
||||
[Janeiro Digital][21]公司架构师总裁 Josh Collins 说，“随着越来越多的开发活动 - 源代码管理，DevOps管道，工作项目跟踪 - 转向API驱动的平台 - 将这些原始数据拼接在一起以描绘组织效率提升的机会和图景”。
|
||||
|
||||
Collins 认为这是一种可能的新型“开发组织度量指标”。但不要误认为这意味着机器和算法可以突然预测IT所做的一切。
|
||||
|
||||
“无论是衡量个人资源还是整体团队，这些指标都可以很强大 - 但应该用大量的背景来衡量。”Collins说，“将这些数据用于高层次趋势并确认定性观察 - 而不是临床评级你的团队。”
|
||||
|
||||
**想要更多这样知识, IT领导者？[注册我们的每周电子邮件通讯][22]。**
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://enterprisersproject.com/article/2018/3/what-s-next-it-automation-6-trends-watch
|
||||
|
||||
作者：[Kevin Casey][a]
|
||||
译者：[MZqk](https://github.com/MZqk)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://enterprisersproject.com/user/kevin-casey
|
||||
[1]:https://enterprisersproject.com/article/2017/12/5-factors-fueling-automation-it-now
|
||||
[2]:https://enterprisersproject.com/article/2017/12/4-trends-watch-it-automation-expands
|
||||
[3]:https://enterprisersproject.com/article/2018/1/getting-started-automation-6-tips
|
||||
[4]:https://enterprisersproject.com/article/2018/1/how-make-case-it-automation
|
||||
[5]:https://enterprisersproject.com/article/2018/1/it-automation-best-practices-7-keys-long-term-success
|
||||
[6]:https://enterprisersproject.com/tags/automation
|
||||
[7]:https://enterprisersproject.com/article/2018/2/how-spot-machine-learning-opportunity
|
||||
[8]:https://www.advsyscon.com/en-us/
|
||||
[9]:https://www.sungardas.com/en/
|
||||
[10]:https://enterprisersproject.com/tags/artificial-intelligence
|
||||
[11]:https://www.solarwinds.com/
|
||||
[12]:https://enterprisersproject.com/article/2017/12/8-emerging-ai-jobs-it-pros
|
||||
[13]:https://www.juniper.net/
|
||||
[14]:https://www.redhat.com/en?intcmp=701f2000000tjyaAAA
|
||||
[15]:https://enterprisersproject.com/article/2018/2/12-bad-enterprise-security-habits-break
|
||||
[16]:https://enterprisersproject.com/article/2018/2/12-bad-enterprise-security-habits-break?sc_cid=70160000000h0aXAAQ
|
||||
[17]:https://opensource.com/tags/ansible
|
||||
[18]:https://datavision.com/
|
||||
[19]:https://opensource.com/article/18/2/tips-success-when-getting-started-ansible?intcmp=701f2000000tjyaAAA
|
||||
[20]:https://enterprisersproject.com/article/2017/7/devops-metrics-are-you-measuring-what-matters?sc_cid=70160000000h0aXAAQ
|
||||
[21]:https://www.janeirodigital.com/
|
||||
[22]:https://enterprisersproject.com/email-newsletter?intcmp=701f2000000tsjPAAQ
|
||||
@ -0,0 +1,156 @@
|
||||
可以考虑的 9 个开源 ERP 系统
|
||||
======
|
||||
|
||||
拥有一定数量员工的企业就需要大量的协调工作，包括价格、生产计划、帐务和财务、管理支出、管理存货等等。把一套截然不同的工具拼接到一起去处理这些工作，是一种粗制滥造和无价值的做法。
|
||||
|
||||
那种方法没有任何弹性。并且那样在各种各样的自组织系统之间高效移动数据是非常困难的。同样，它也很难维护。
|
||||
|
||||
因此，大多数成长型企业都转而使用一个 [企业资源计划][1] (ERP) 系统。
|
||||
|
||||
在这个行业中的大咖有 Oracle、SAP、以及 Microsoft Dynamics。它们都提供了一个综合的系统，但同时也很昂贵。如果你的企业支付不起如此昂贵的大系统，或者你仅需要一个简单的系统，怎么办呢？你可以使用开源的产品来作为替代。
|
||||
|
||||
### 一个 ERP 系统中有什么东西
|
||||
|
||||
显然，你希望有一个满足你需要的系统。基于那些需要，更多的功能并不意味着就更好。但是，你的需要会根据你的业务的增长而变化的，因此，你希望能够找到一个 ERP 系统，它能够根据你新的需要而扩展它。那就意味着系统有额外的模块或者支持插件和附加功能。
|
||||
|
||||
大多数的开源 ERP 系统都是 web 应用程序。你可以下载并将它们安装到你的服务器上。但是，如果你不希望（或者没有相应技能或者人员）自己去维护系统，那么应该确保它们的应用程序提供托管版本。
|
||||
|
||||
最后，你还应该确保应用程序有良好的文档和支持 —— 要么是付费支持或者有一个活跃的用户社区。
|
||||
|
||||
有很多弹性很好的、功能丰富的、很划算的开源 ERP 系统。如果你正打算购买这样的系统，这里有我们挑选出来的 9 个。
|
||||
|
||||
### ADempiere
|
||||
|
||||
像大多数其它开源 ERP 解决方案，[ADempiere][2] 的目标客户是中小企业。它已经存在一段时间了— 这个项目出现于 2006，它是 Compiere ERP 软件的一个分支。
|
||||
|
||||
它的意大利语名字的意思是“实现”或者“满足”，它“涉及多个方面”的 ERP 特性旨在帮企业去满足各种需求。它在 ERP 中增加了供应链管理（SCM）和客户关系管理（CRM）功能，能够让 ERP 套件在一个软件中去管理销售、采购、库存、以及帐务处理。它的最新版本是 v.3.9.0，更新了用户界面、销售点、人力资源、工资、以及其它的特性。
|
||||
|
||||
因为是一个跨平台的、基于 Java 的云解决方案，ADempiere 可以运行在Linux、Unix、Windows、MacOS、智能手机、平板电脑上。它使用 [GPLv2][3] 授权。如果你想了解更多信息，这里有一个用于测试的 [demo][4]，或者也可以在 GitHub 上查看它的 [源代码][5]。
|
||||
|
||||
### Apache OFBiz
|
||||
|
||||
[Apache OFBiz][6] 的业务相关的套件是构建在通用的架构上的，它允许企业根据自己的需要去定制 ERP。因此，它是有内部开发资源的大中型企业去修改和集成它到它们现有的 IT 和业务流程的最佳套件。
|
||||
|
||||
OFBiz 是一个成熟的开源 ERP 系统；它的网站上说它是一个有十年历史的顶级 Apache 项目。可用的 [模块][7] 有帐务、生产制造、人力资源、存货管理、目录管理、客户关系管理、以及电子商务。你可以在它的 [demo 页面][8] 上试用电子商务的网上商店以及后端的 ERP 应用程序。
|
||||
|
||||
Apache OFBiz 的源代码能够在它的 [项目仓库][9] 中找到。它是用 Java 写的，它在 [Apache 2.0 license][10] 下可用。
|
||||
|
||||
### Dolibarr
|
||||
|
||||
[Dolibarr][11] 提供了中小型企业端到端的业务管理，从发票跟踪、合同、存货、订单、以及支付，到文档管理和电子化 POS 系统支持。它的全部功能封装在一个清晰的界面中。
|
||||
|
||||
如果你担心不会使用 Dolibarr，[这里有一些关于它的文档][12]。
|
||||
|
||||
另外，还有一个 [在线演示][13]，Dolibarr 也有一个 [插件商店][14]，你可以在那是购买一些软件来扩展它的功能。你可以在 GitHub 上查看它的 [源代码][15]；它在 [GPLv3][16] 或者任何它的最新版本许可下面使用。
|
||||
|
||||
### ERPNext
|
||||
|
||||
[ERPNext][17] 是这类开源项目中的其中一个；实际上它最初 [出现在 Opensource.com][18]。它被设计用于打破一个陈旧而昂贵的专用 ERP 系统的垄断局面。
|
||||
|
||||
ERPNext 适合于中小型企业。它包含的模块有帐务、存货管理、销售、采购、以及项目管理。ERPNext 是表单驱动的应用程序 — 你可以在一组字段中填入信息，然后让应用程序去完成剩余部分。整个套件非常易用。
|
||||
|
||||
如果你感兴趣，在你考虑参与之前，你可以请求获取一个 [demo][19]，去 [下载它][20] 或者在托管服务上 [购买一个订阅][21]。
|
||||
|
||||
### Metasfresh
|
||||
|
||||
[Metasfresh][22] 的名字表示它承诺软件的代码始终保持“新鲜”。它自 2015 年以来每周发行一个更新版本，那时，它的代码是由创始人从 ADempiere 项目中 fork 的。与 ADempiere 一样，它是一个基于 Java 的开源 ERP，目标客户是中小型企业。
|
||||
|
||||
虽然，相比在这里介绍的其它软件来说，它是一个很 “年青的” 项目，但是它早早就引起了一起人的注意，获得很多积极的评价，比如，被提名为“最佳开源”的 IT 创新奖入围者。
|
||||
|
||||
Metasfresh 在自托管系统上或者在云上单用户使用时是免费的，或者可以按月交纳订阅费用。它的 [源代码][23] 在 GitHub 上，可以在遵守 [GPLv2][24] 许可的情况下使用，它的云版本是以 GPLv3 方式授权使用。
|
||||
|
||||
### Odoo
|
||||
|
||||
[Odoo][25] 是一个应用程序集成解决方案，它包含的模块有项目管理、帐单、存货管理、生产制造、以及采购。这些模块之间可以相互通讯，实现高效平滑地信息交换。
|
||||
|
||||
虽然 ERP 可能很复杂，但是，Odoo 通过简单的，甚至是简洁的界面使它变得很友好。这个界面让人联想到谷歌云盘，它只让你需要的功能可见。在你决定签定采购合同之前，你可以 [得到一个 Odoo 去试用][26]。
|
||||
|
||||
Odoo 是基于 web 的工具。按单个模块来订阅的话，每个模块每月需要支付 20 美元。你也可以 [下载它][27]，或者可以从 GitHub 上获得 [源代码][28]，它以 [LGPLv3][29] 方式授权。
|
||||
|
||||
### Opentaps
|
||||
|
||||
[Opentaps][30] 是专为大型业务设计的几个开源 ERP 解决方案之一，它的功能强大而灵活。这并不奇怪，因为它是在 Apache OFBiz 基础之上构建的。
|
||||
|
||||
你可以得到你所希望的模块组合，来帮你管理存货、生产制造、财务、以及采购。它也有分析功能，帮你去分析业务的各个方面。你可以借助这些信息让未来的计划做的更好。Opentaps 也包含一个强大的报表功能。
|
||||
|
||||
在它的基础之上，你还可以 [购买一些插件和附加模块][31] 去增强 Opentaps 的功能。包括与 Amazon Marketplace Services 和 FedEx 的集成等。在你 [下载 Opentaps][32] 之前，你可以到 [在线 demo][33] 上试用一下。它遵守 [GPLv3][34] 许可。
|
||||
|
||||
### WebERP
|
||||
|
||||
[WebERP][35] 是一个如它的名字所表示的那样：一个通过 Web 浏览器来使用的 ERP 系统。另外还需要的其它软件只有一个，那就是查看报告所使用的 PDF 阅读器。
|
||||
|
||||
具体来说，它是一个面向批发、分销、生产制造业务的账务和业务管理解决方案。它也可以与 [第三方的业务软件][36] 集成，包括多地点零售管理的销售点系统、电子商务模块、以及构建业务知识库的 wiki 软件。它是用 PHP 写的，并且它致力于成为低资源占用、高效、快速、以及平台无关的、普通商业用户易于使用的 ERP 系统。
|
||||
|
||||
WebERP 正在积极地进行开发，并且它有一个活跃的 [论坛][37]，在那里你可以咨询问题或者学习关于如何使用这个应用程序的相关知识。你也可以试用一个 [demo][38]，或者在 GitHub 上下载它的 [源代码][39]（遵守 [GPLv2][40] 许可）
|
||||
|
||||
### xTuple PostBooks
|
||||
|
||||
如果你的生产制造、分销、电子商务业务已经从小规模业务成长起来了，并且正在寻找一个适合你的成长型企业的 ERP 系统，那么，你可以去了解一下 [xTuple PostBooks][41]。它是围绕核心 ERP 功能、帐务、以及可以添加存货、分销、采购、以及供应商报告等 CRM 功能构建的全面解决方案的系统。
|
||||
|
||||
xTuple 在通用公共属性许可证（[CPAL][42]）下使用，并且这个项目欢迎开发者去 fork 它，然后为基于存货的生产制造型企业开发其它的业务软件。它的基于 web 的核心是用 JavaScript 写的，它的 [源代码][43] 可以在 GitHub 上找到。你可以去在 xTuple 的网站上注册一个免费的 [demo][44] 去了解它。
|
||||
|
||||
还有许多其它的开源 ERP 可供你选择 — 另外你可以去了解的还有 [Tryton][45]，它是用 Python 写的，并且使用的是 PostgreSQL 数据库引擎，或者基于 Java 的 [Axelor][46]，它的好处是用户可以使用拖放界面来创建或者修改业务应用。如果还有在这里没有列出的你喜欢的开源 ERP 解决方案，请在下面的评论区共享出来。你也可以去查看我们的 [供应链管理工具][47] 榜单。
|
||||
|
||||
这篇文章是 [以前版本][48] 的一个更新版，它是由 Opensource.com 的主席 [Scott Nesbitt][49] 所写。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/tools/enterprise-resource-planning
|
||||
|
||||
作者：[Opensource.com][a]
|
||||
译者：[qhwdw](https://github.com/qhwdw)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://opensource.com
|
||||
[1]:http://en.wikipedia.org/wiki/Enterprise_resource_planning
|
||||
[2]:http://www.adempiere.net/welcome
|
||||
[3]:http://wiki.adempiere.net/License
|
||||
[4]:http://www.adempiere.net/web/guest/demo
|
||||
[5]:https://github.com/adempiere/adempiere
|
||||
[6]:http://ofbiz.apache.org/
|
||||
[7]:https://ofbiz.apache.org/business-users.html#UsrModules
|
||||
[8]:http://ofbiz.apache.org/ofbiz-demos.html
|
||||
[9]:http://ofbiz.apache.org/source-repositories.html
|
||||
[10]:http://www.apache.org/licenses/LICENSE-2.0
|
||||
[11]:http://www.dolibarr.org/
|
||||
[12]:http://wiki.dolibarr.org/index.php/What_Dolibarr_can%27t_do
|
||||
[13]:http://www.dolibarr.org/onlinedemo
|
||||
[14]:http://www.dolistore.com/
|
||||
[15]:https://github.com/Dolibarr/dolibarr
|
||||
[16]:https://github.com/Dolibarr/dolibarr/blob/develop/COPYING
|
||||
[17]:https://erpnext.com/
|
||||
[18]:https://opensource.com/business/14/11/building-open-source-erp
|
||||
[19]:https://frappe.erpnext.com/request-a-demo
|
||||
[20]:https://erpnext.com/download
|
||||
[21]:https://erpnext.com/pricing
|
||||
[22]:http://metasfresh.com/en/
|
||||
[23]:https://github.com/metasfresh/metasfresh
|
||||
[24]:https://github.com/metasfresh/metasfresh/blob/master/LICENSE.md
|
||||
[25]:https://www.odoo.com/
|
||||
[26]:https://www.odoo.com/page/start
|
||||
[27]:https://www.odoo.com/page/download
|
||||
[28]:https://github.com/odoo
|
||||
[29]:https://github.com/odoo/odoo/blob/11.0/LICENSE
|
||||
[30]:http://www.opentaps.org/
|
||||
[31]:http://shop.opentaps.org/
|
||||
[32]:http://www.opentaps.org/products/download
|
||||
[33]:http://www.opentaps.org/products/online-demo
|
||||
[34]:https://www.gnu.org/licenses/agpl-3.0.html
|
||||
[35]:http://www.weberp.org/
|
||||
[36]:http://www.weberp.org/Links.html
|
||||
[37]:http://www.weberp.org/forum/
|
||||
[38]:http://www.weberp.org/weberp/
|
||||
[39]:https://github.com/webERP-team/webERP
|
||||
[40]:https://github.com/webERP-team/webERP#legal
|
||||
[41]:https://xtuple.com/
|
||||
[42]:https://xtuple.com/products/license-options#cpal
|
||||
[43]:http://xtuple.github.io/
|
||||
[44]:https://xtuple.com/free-demo
|
||||
[45]:http://www.tryton.org/
|
||||
[46]:https://www.axelor.com/
|
||||
[47]:https://opensource.com/tools/supply-chain-management
|
||||
[48]:https://opensource.com/article/16/3/top-4-open-source-erp-systems
|
||||
[49]:https://opensource.com/users/scottnesbitt
|
||||
227
translated/tech/20180504 A Beginners Guide To Cron Jobs.md
Normal file
227
translated/tech/20180504 A Beginners Guide To Cron Jobs.md
Normal file
@ -0,0 +1,227 @@
|
||||
Cron 任务入门指南
|
||||
======
|
||||
|
||||
|
||||
** Cron **是您可以在任何类 Unix 操作系统中找到的最有用的实用程序之一。它用于安排命令在特定时间执行。这些预定的命令或任务被称为 “Cron 任务”。Cron 通常用于运行计划备份，监视磁盘空间，定期删除不再需要的文件（例如日志文件），运行系统维护任务等等。在本简要指南中，我们将看到 Linux 中 Cron 任务 的基本用法。
|
||||
|
||||
Cron 任务入门指南
|
||||
|
||||
cron 任务的典型格式是：
|
||||
```
|
||||
Minute(0-59) Hour(0-24) Day_of_month(1-31) Month(1-12) Day_of_week(0-6) Command_to_execute
|
||||
```
|
||||
|
||||
只需记住 cron 任务的格式或打印下面的插图并将其放在你桌面上即可。
|
||||
|
||||
![][2]
|
||||
|
||||
在上图中，星号表示特定的时间块。
|
||||
|
||||
要显示当前登录用户的 ** crontab ** 文件的内容：
|
||||
```
|
||||
$ crontab -l
|
||||
|
||||
```
|
||||
|
||||
要编辑当前用户的 cron 任务，请执行以下操作：
|
||||
```
|
||||
$ crontab -e
|
||||
```
|
||||
|
||||
如果这是第一次编辑此文件，你将需要使用编辑器来编辑此文件。
|
||||
```
|
||||
no crontab for sk - using an empty one
|
||||
|
||||
Select an editor. To change later, run 'select-editor'.
|
||||
1. /bin/nano <---- easiest
|
||||
2. /usr/bin/vim.basic
|
||||
3. /usr/bin/vim.tiny
|
||||
4. /bin/ed
|
||||
|
||||
Choose 1-4 [1]:
|
||||
|
||||
```
|
||||
|
||||
选择适合你的编辑器。这里是一个示例crontab文件的样子。
|
||||
|
||||
![][3]
|
||||
|
||||
在这个文件中，你需要添加你的 cron 任务s。
|
||||
|
||||
要编辑其他用户的crontab，例如 ostechnix，请执行：
|
||||
```
|
||||
$ crontab -u ostechnix -e
|
||||
```
|
||||
|
||||
让我们看看一些例子。
|
||||
|
||||
要 **每分钟** 执行一次 cron 任务 , 需使用如下格式.
|
||||
```
|
||||
* * * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
要每5分钟运行一次cron 任务，请在crontab文件中添加以下内容。
|
||||
```
|
||||
*/5 * * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
要在每 1/4 个小时（每15分钟）运行一次 cron 任务，请添加以下内容：
|
||||
```
|
||||
*/15 * * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
要每小时的第30分钟运行一次 cron 任务，请运行：
|
||||
```
|
||||
30 * * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
您还可以使用逗号定义多个时间间隔。例如，以下 cron 任务 每小时运行三次，分别在第 0, 5 和 10 分钟运行：
|
||||
```
|
||||
0,5,10 * * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
每半小时运行一次 cron 任务：
|
||||
```
|
||||
*/30 * * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
每小时运行一次：
|
||||
```
|
||||
0 * * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
每2小时运行一次：
|
||||
```
|
||||
0 */2 * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
每天运行一项（在00:00运行）：
|
||||
```
|
||||
0 0 * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
每天凌晨3点运行：
|
||||
```
|
||||
0 3 * * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
每周日运行：
|
||||
```
|
||||
0 0 * * SUN <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
或使用，
|
||||
```
|
||||
0 0 * * 0 <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
它将在每周日的午夜 00:00 运行。
|
||||
|
||||
星期一至星期五每天运行一次，亦即每个工作日运行一次：
|
||||
```
|
||||
0 0 * * 1-5 <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
这项工作将于00:00开始。
|
||||
|
||||
每个月运行一次：
|
||||
```
|
||||
0 0 1 * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
于每月第1天的16:15运行：
|
||||
```
|
||||
15 16 1 * * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
每季度运行一次，亦即每隔3个月的第1天运行：
|
||||
```
|
||||
0 0 1 */3 * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
在特定月份的特定时间运行：
|
||||
```
|
||||
5 0 * 4 * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
每个四月的 00:05 运行。
|
||||
|
||||
每6个月运行：
|
||||
```
|
||||
0 0 1 */6 * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
这个定时任务将在每六个月的第一天的 00:00 运行。
|
||||
|
||||
每年运行：
|
||||
```
|
||||
0 0 1 1 * <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
这项 cron 任务将于 1 月份的第一天的 00:00 运行。
|
||||
|
||||
我们也可以使用以下字符串来定义任务。
|
||||
|
||||
@reboot 在每次启动时运行一次。 @yearly 每年运行一次。 @annually（和 @yearly 一样）。 @monthly 每月运行一次。 @weekly 每周运行一次。 @daily 每天运行一次。 @midnight （和 @daily 一样）。 @hourly 每小时运行一次。
|
||||
|
||||
例如，要在每次重新启动服务器时运行任务，请将此行添加到您的 crontab 文件中。
|
||||
```
|
||||
@reboot <command-to-execute>
|
||||
|
||||
```
|
||||
|
||||
要删除当前用户的所有 cron 任务：
|
||||
```
|
||||
$ crontab -r
|
||||
|
||||
```
|
||||
|
||||
还有一个名为 [** crontab.guru **] [4] 的专业网站，用于学习 cron 任务示例。这个网站提供了很多 cron 任务的例子。
|
||||
|
||||
有关更多详细信息，请查看手册页。
|
||||
```
|
||||
$ man crontab
|
||||
|
||||
```
|
||||
|
||||
那么，就是这样。到此为止，您应该对 cron 任务以及如何在世使用它们有了一个基本的了解。后续还会介绍更多的优秀工具。敬请关注！！
|
||||
|
||||
干杯!
|
||||
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.ostechnix.com/a-beginners-guide-to-cron-任务s/
|
||||
|
||||
作者：[SK][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[译者KevinSJ](https://github.com/KevinSJ)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://www.ostechnix.com/author/sk/
|
||||
[1]:data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7
|
||||
[2]:http://www.ostechnix.com/wp-content/uploads/2018/05/cron-任务-format-1.png
|
||||
[3]:http://www.ostechnix.com/wp-content/uploads/2018/05/cron-任务s-1.png
|
||||
[4]:https://crontab.guru/
|
||||
@ -0,0 +1,106 @@
|
||||
如何在 Linux 系统中结束结束进程或是中止程序
|
||||
======
|
||||
|
||||
|
||||
|
||||
进程出错的时候，您可能会想要中止或是中断这个进程。本文，我们将在命令行和图形界面中探索进程或是应用程序的中断，这里我们使用 [gedit][1] 作为样例程序。
|
||||
|
||||
### 使用命令行、终端字符
|
||||
|
||||
#### Ctrl + C
|
||||
|
||||
在命令行中调用 `gedit` （如果您没有使用 `gedit &` 命令）程序发生错误时，shell 会话被阻塞，将不会释放出相应的错误提示，此下，`Ctrl + C` （Ctrl 和 C 的组合键） 会很管用。`gedit` 会被中断，由于 `Ctrl + C` 给 `gedit` 发送了 `SIGINT` 信号，之前的所有工作都将丢失（除非文件已经被保存）。`SIGINT` 是一个会默认执行进程中断的终止信号，它将指示 shell 终止 `gedit` 的运行，并返回到主函数的循环中，此时，您将得到提示语。
|
||||
|
||||
```
|
||||
$ gedit
|
||||
^C
|
||||
```
|
||||
|
||||
#### Ctrl + Z
|
||||
|
||||
它被称为挂起字符，能够为进程发送 `SIGTSTP` 信号。它也是一个中止信号，但是默认行为不是杀死进程，而是挂起进程。
|
||||
|
||||
下面的命令将会停止（杀死/中断） `gedit` 的运行，并返回 shell 提示。
|
||||
```
|
||||
$ gedit
|
||||
^Z
|
||||
[1]+ Stopped gedit
|
||||
$
|
||||
```
|
||||
|
||||
一旦进程被挂起（以 `gedit` 为例），将不能在 `gedit` 中做任何事情。而在后台，该进程任然是一个作业，可以使用 `jsbs` 命令验证。
|
||||
```
|
||||
$ jobs
|
||||
[1]+ Stopped gedit
|
||||
```
|
||||
|
||||
`jobs` 允许您在单个 shell 会话中控制多个进程。您可以在前台或是后台终止，恢复或是移动作业。
|
||||
|
||||
让我们在后台恢复 `gedit`，释放提示并运行其它命令吧。您可以根据作业 ID（注意，`jobs` 命令显示出来的 `[1]` 就是作业 ID）使用 `bg` 命令恢复进程。
|
||||
```
|
||||
$ bg 1
|
||||
[1]+ gedit &
|
||||
```
|
||||
|
||||
这和直接使用 `gedit &` 启动程序效果差不多：
|
||||
```
|
||||
$ gedit &
|
||||
```
|
||||
|
||||
### 使用 kill
|
||||
|
||||
`kill` 命令提供信号的精确控制，允许您通过进程 ID 或是 PID，根据特定的信号名或是信号数字为进程发送信号。
|
||||
|
||||
`kill` 命令能够根据作业 ID 控制进程，这一点是我喜欢的。让我们使用 `gedit &` 命令在后台开启 `gedit` 服务。假设通过 `jobs` 命令我得到了一个 `gedit` 的作业 ID，让我们为 `gedit` 发送 `SIGINT` 信号吧：
|
||||
```
|
||||
$ kill -s SIGINT %1
|
||||
```
|
||||
|
||||
作业 ID 需要使用 `%` 前缀，不然 `kill` 会将其视作 PID。
|
||||
|
||||
不明确指定的信号，`kill` 仍然可以工作。此时，默认会发送能中断进程的 `SIGTERM` 信号。执行 `kill -l` 查看信号名列表，使用 `man kill` 命令阅读手册。
|
||||
|
||||
### 使用 killall
|
||||
|
||||
如果您不想使用特定的工作 ID 或者 PID，`killall` 允许您使用特定的进程名。中断 `gedit` 最简单的 `killall` 使用方式是：
|
||||
```
|
||||
$ killall gedit
|
||||
```
|
||||
|
||||
它将终止所有名为 `gedit` 的进程。和 `kill` 想死，默认发送的信号时 `SIGTERM`。
|
||||
This will kill all the processes with the name `gedit`. Like `kill`, the default signal is `SIGTERM`. 使用 `-I` 选项忽略大小写。
|
||||
```
|
||||
$ gedit &
|
||||
[1] 14852
|
||||
|
||||
$ killall -I GEDIT
|
||||
[1]+ Terminated gedit
|
||||
```
|
||||
|
||||
查看手册学习更多 `killall` 命令选项（如 `-u`）。
|
||||
|
||||
### 使用 xkill
|
||||
|
||||
您是否遇见过播放器崩溃，比如 [VLC][2] 灰屏或挂起？现在，获得程序 PID 之后，您就可以使用 `xkill` 命令终止应用程序。
|
||||
|
||||
![Using xkill][3]
|
||||
|
||||
`xkill` 允许您使用鼠标关闭窗口。仅需在终端执行 `xkill` 命令，它将会改变鼠标光标为一个 **X** 或是一个骷髅图标。点击您想关闭的进程窗口上的 **X**。小心使用 `xkill`，如手册描述的一致，它很危险。我已经提醒过您了！
|
||||
|
||||
参阅手册，了解上述命令更多信息。您还可以接续探索 `pkill` 和 `pgrep` 命令。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/5/how-kill-process-stop-program-linux
|
||||
|
||||
作者：[Sachin Patil][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[CYLeft](https://github.com/CYLeft)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://opensource.com/users/psachin
|
||||
[1]:https://wiki.gnome.org/Apps/Gedit
|
||||
[2]:https://www.videolan.org/vlc/index.html
|
||||
[3]:https://opensource.com/sites/default/files/styles/panopoly_image_original/public/uploads/xkill_gedit.png?itok=TBvMw0TN (Using xkill)
|
||||
@ -0,0 +1,98 @@
|
||||
使用 Buildah 创建小体积的容器
|
||||
======
|
||||
|
||||
我最近加入了 Red Hat，在这之前我在另外一家科技公司工作了很多年。在我的上一份工作岗位上，我开发了不少不同类型的软件产品，这些产品是成功的，但都有版权保护。不仅法规限制了我们不能在公司外将软件共享，而且我们在公司内部也基本不进行共享。在那时，我觉得这很有道理：公司花费了时间、精力和预算用于开发软件，理应保护并要求软件涉及的利益。
|
||||
|
||||
时间如梭，去年我加入 Red Hat 并培养出一种完全不同的理念。[Buildah 项目][1]是我最早加入的项目之一，该项目用于构建 OCI (Open Container Initiative) 标准的镜像，特别擅长让你精简已创建镜像的体积。那时 Buildah 还处于非常早期的阶段，包含一些瑕疵，不适合用于生产环境。
|
||||
|
||||
刚接触项目不久，我做了一些小变更，然后询问公司内部 git 仓库地址，以便提交我做的变更。收到的回答是：没有内部仓库，直接将变更提交到 GitHub 上。这让我感到困惑，将我的变更提交到 GitHub 意味着：任何人都可以查看这部分代码并在他们自己的项目中使用。况且代码还有一些瑕疵，这样做简直有悖常理。但作为一个新人，我只是惊讶地摇了摇头并提交了变更。
|
||||
|
||||
一年后，我终于相信了开源软件的力量和价值。我仍为 Buildah 项目工作，我们最近遇到的一个主题很形象地说明了这种力量和价值。标题为 [Buildah 镜像体积并不小？][2] 的主题由 Tim Dudgeon (@tdudgeon) 提出。简而言之，他发现使用 Buildah 创建的镜像比使用 Docker 创建的镜像体积更大，而且 Buildah 镜像中并不包含一些额外应用，但 Docker 镜像中却包含它们。
|
||||
|
||||
为了比较，他首先操作如下：
|
||||
```
|
||||
$ docker pull centos:7
|
||||
$ docker images
|
||||
REPOSITORY TAG IMAGE ID CREATED SIZE
|
||||
docker.io/centos 7 2d194b392dd1 2 weeks ago 195 MB
|
||||
```
|
||||
|
||||
他发现 Docker 镜像的体积为 195MB。Tim 接着使用 Buildah 创建了一个（基于 scratch 的）最小化镜像，仅仅将 `coreutils` 和 `bash` 软件包加入到镜像中，使用的脚本如下：
|
||||
```
|
||||
$ cat ./buildah-base.sh
|
||||
#!/bin/bash
|
||||
|
||||
set -x
|
||||
|
||||
# build a minimal image
|
||||
newcontainer=$(buildah from scratch)
|
||||
scratchmnt=$(buildah mount $newcontainer)
|
||||
|
||||
# install the packages
|
||||
yum install --installroot $scratchmnt bash coreutils --releasever 7 --setopt install_weak_deps=false -y
|
||||
yum clean all -y --installroot $scratchmnt --releasever 7
|
||||
|
||||
sudo buildah config --cmd /bin/bash $newcontainer
|
||||
|
||||
# set some config info
|
||||
buildah config --label name=centos-base $newcontainer
|
||||
|
||||
# commit the image
|
||||
buildah unmount $newcontainer
|
||||
buildah commit $newcontainer centos-base
|
||||
|
||||
$ sudo ./buildah-base.sh
|
||||
|
||||
$ sudo buildah images
|
||||
IMAGE ID IMAGE NAME CREATED AT SIZE
|
||||
8379315d3e3e docker.io/library/centos-base:latest Mar 25, 2018 17:08 212.1 MB
|
||||
```
|
||||
|
||||
Tim 想知道为何 Buildah 镜像体积反而大 17MB，毕竟 `python` 和 `yum` 软件包都没有安装到 Buildah 镜像中，而这些软件已经安装到 Docker 镜像中。这个结果并不符合预期，在 Github 的相关主题中引发了广泛的讨论。
|
||||
|
||||
不仅 Red Hat 的员工参与了讨论，还有不少公司外人士也加入了讨论，这很有意义。值得一提的是，GitHub 用户 @pixdrift 主导了很多重要的讨论并提出很多发现，他指出在 Buildah 镜像中文档和语言包就占据了比 100MB 略多一点的空间。Pixdrift 建议在 yum 安装器中强制指定语言，据此提出如下修改过的 `buildah-bash.sh` 脚本：
|
||||
```
|
||||
#!/bin/bash
|
||||
|
||||
set -x
|
||||
|
||||
# build a minimal image
|
||||
newcontainer=$(buildah from scratch)
|
||||
scratchmnt=$(buildah mount $newcontainer)
|
||||
|
||||
# install the packages
|
||||
yum install --installroot $scratchmnt bash coreutils --releasever 7 --setopt=install_weak_deps=false --setopt=tsflags=nodocs --setopt=override_install_langs=en_US.utf8 -y
|
||||
yum clean all -y --installroot $scratchmnt --releasever 7
|
||||
|
||||
sudo buildah config --cmd /bin/bash $newcontainer
|
||||
|
||||
# set some config info
|
||||
buildah config --label name=centos-base $newcontainer
|
||||
|
||||
# commit the image
|
||||
buildah unmount $newcontainer
|
||||
buildah commit $newcontainer centos-base
|
||||
```
|
||||
|
||||
Tim 运行这个新脚本，得到的镜像体积缩减至 92MB，相比之前的 Buildah 镜像体积减少了 120MB，这比较接近我们的预期；然而，c出于工程师的天性，56% 的体积缩减不能让他们满足。讨论继续深入下去，涉及如何移除个人语言包以节省更多空间。如果想了解讨论细节，点击 [Buildah 镜像体积并不小？][2] 链接。说不定你也能给出有帮助的点子，甚至更进一步成为 Buildah 项目的贡献者。这个主题的解决从一个侧面告诉我们，Buildah 软件可以多么快速和容易地创建体积最小化的容器，该容器仅包含你高效运行任务所需的软件。额外的好处是，你无需运行一个守护进程。
|
||||
|
||||
这个镜像体积缩减的主题让我意识到开源软件的力量。来自不同公司的大量开发者，在一天多的时间内，以开放讨论的形式进行合作解决问题。虽然解决这个具体问题并没有修改已有代码，但 Red Hat 公司外开发者对 Buildah 做了很多代码贡献，进而帮助项目变得更好。这些贡献也吸引了更多人才关注项目代码；如果像之前那样，代码作为版权保护软件的一部分放置在私有 git 仓库中，不会获得上述好处。我只用了一年的时间就转向拥抱 [开源方式][3]，而且可能不会再转回去了。
|
||||
|
||||
文章最初发表于 [Project Atomic][4]，已获得转载许可。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/5/containers-buildah
|
||||
|
||||
作者：[Tom Sweeney][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[pinewall](https://github.com/pinewall)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://opensource.com/users/tomsweeneyredhat
|
||||
[1]:https://github.com/projectatomic/buildah
|
||||
[2]:https://github.com/projectatomic/buildah/issues/532
|
||||
[3]:https://twitter.com/opensourceway
|
||||
[4]:http://www.projectatomic.io/blog/2018/04/open-source-what-a-concept/
|
||||
@ -0,0 +1,216 @@
|
||||
使用 GNU Parallel 提高 Linux 命令行执行效率
|
||||
======
|
||||
|
||||
|
||||
|
||||
你是否有过这种感觉，你的主机运行速度没有预期的那么快？我也曾经有过这种感觉，直到我发现了 GNU Parallel。
|
||||
|
||||
GNU Parallel 是一个 shell 工具，可以并行执行任务。它可以解析多种输入，让你可以同时在多份数据上运行脚本或命令。你终于可以使用全部的 CPU 了！
|
||||
|
||||
如果你用过 `xargs`，上手 Parallel 几乎没有难度。如果没有用过，这篇教程会告诉你如何使用，同时给出一些其它的用例。
|
||||
|
||||
### 安装 GNU Parallel
|
||||
|
||||
GNU Parallel 很可能没有预装在你的 Linux 或 BSD 主机上，你可以从软件源（Linux 对应 repository，BSD 对应 ports collection）中安装。以 Fedora 为例：
|
||||
```
|
||||
$ sudo dnf install parallel
|
||||
|
||||
```
|
||||
|
||||
对于 NetBSD：
|
||||
```
|
||||
# pkg_add parallel
|
||||
|
||||
```
|
||||
|
||||
如果各种方式都不成功，请参考[项目主页][1]。
|
||||
|
||||
### 从串行到并行
|
||||
|
||||
正如其名称所示，Parallel 的强大之处是以并行方式执行任务；而我们中不少人平时仍然以串行方式运行任务。
|
||||
|
||||
当你对多个对象执行某个命令时，你实际上创建了一个任务队列。一部分对象可以被命令处理，剩余的对象需要等待，直到命令处理它们。这种方式是低效的。只要数据够多，总会形成任务队列；但与其只使用一个任务队列，为何不使用多个更小规模的任务队列呢？
|
||||
|
||||
假设你有一个图片目录，你希望将目录中的图片从 JEEG 格式转换为 PNG 格式。有多种方法可以完成这个任务。可以手动用 GIMP 打开每个图片，输出成新格式，但这基本是最差的选择，费时费力。
|
||||
|
||||
上述方法有一个漂亮且简洁的变种，即基于 shell 的方案：
|
||||
```
|
||||
$ convert 001.jpeg 001.png
|
||||
$ convert 002.jpeg 002.png
|
||||
$ convert 003.jpeg 003.png
|
||||
... 略 ...
|
||||
|
||||
```
|
||||
|
||||
对于初学者而言，这是一个不小的转变，而且看起来是个不小的改进。不再需要图像界面和不断的鼠标点击，但仍然是费力的。
|
||||
|
||||
进一步改进：
|
||||
```
|
||||
$ for i in *jpeg; do convert $i $i.png ; done
|
||||
|
||||
```
|
||||
|
||||
至少，这一步设置好任务执行，让你节省时间去做更有价值的事情。但问题来了，这仍然是串行操作；一张图片转换完成后，队列中的下一张进行转换，依此类推直到全部完成。
|
||||
|
||||
使用 Parallel:
|
||||
```
|
||||
$ find . -name "*jpeg" | parallel -I% --max-args 1 convert % %.png
|
||||
|
||||
```
|
||||
|
||||
这是两条命令的组合：`find` 命令，用于收集需要操作的对象；`parallel` 命令，用于对象排序并确保每个对象按需处理。
|
||||
|
||||
* `find . -name "*jpeg"` 查找当前目录下以 `jpeg` 结尾的所有文件。
|
||||
* `parallel` 调用 GNU Parallel。
|
||||
* `-I%` 创建了一个占位符 `%`，代表 `find` 传递给 Parallel 的内容。如果不使用占位符，你需要对 `find` 命令的每一个结果手动编写一个命令，而这恰恰是你想要避免的。
|
||||
* `--max-args 1` 给出 Parallel 从队列获取新对象的速率限制。考虑到 Parallel 运行的命令只需要一个文件输入，这里将速率限制设置为 1。假如你需要执行更复杂的命令，需要两个文件输入（例如 `cat 001.txt 002.txt > new.txt`），你需要将速率限制设置为 2。
|
||||
* `convert % %.png` 是你希望 Parallel 执行的命令。
|
||||
|
||||
|
||||
组合命令的执行效果如下：`find` 命令收集所有相关的文件信息并传递给 `parallel`，后者（使用当前参数）启动一个任务，（无需等待任务完成）立即获取参数行中的下一个参数（注：管道输出的每一行对应 `parallel` 的一个参数，所有参数构成参数行）；只要你的主机没有瘫痪，Parallel 会不断做这样的操作。旧任务完成后，Parallel 会为分配新任务，直到所有数据都处理完成。不使用 Parallel 完成任务大约需要 10 分钟，使用后仅需 3 至 5 分钟。
|
||||
|
||||
### 多个输入
|
||||
|
||||
只要你熟悉 `find` 和 `xargs` （整体被称为 GNU 查找工具，或 `findutils`）,`find` 命令是一个完美的 Parallel 数据提供者。它提供了灵活的接口，大多数 Linux 用户已经很习惯使用，即使对于初学者也很容易学习。
|
||||
|
||||
`find` 命令十分直截了当：你向 `find` 提供搜索路径和待查找文件的一部分信息。可以使用通配符完成模糊搜索；在下面的例子中，星号匹配任何字符，故 `find` 定位（文件名）以字符 `searchterm` 结尾的全部文件：
|
||||
```
|
||||
$ find /path/to/directory -name "*searchterm"
|
||||
|
||||
```
|
||||
|
||||
默认情况下，`find` 逐行返回搜索结果，每个结果对应 1 行：
|
||||
```
|
||||
$ find ~/graphics -name "*jpg"
|
||||
/home/seth/graphics/001.jpg
|
||||
/home/seth/graphics/cat.jpg
|
||||
/home/seth/graphics/penguin.jpg
|
||||
/home/seth/graphics/IMG_0135.jpg
|
||||
|
||||
```
|
||||
|
||||
当使用管道将 `find` 的结果传递给 `parallel` 时，每一行中的文件路径被视为 `parallel` 命令的一个参数。另一方面，如果你需要使用命令处理多个参数，你可以改变队列数据传递给 `parallel` 的方式。
|
||||
|
||||
下面先给出一个不那么真实的例子，后续会做一些修改使其更加有意义。如果你安装了 GNU Parallel，你可以跟着这个例子操作。
|
||||
|
||||
假设你有 4 个文件，按照每行一个文件的方式列出，具体如下：
|
||||
```
|
||||
$ echo ada > ada ; echo lovelace > lovelace
|
||||
$ echo richard > richard ; echo stallman > stallman
|
||||
$ ls -1
|
||||
ada
|
||||
lovelace
|
||||
richard
|
||||
stallman
|
||||
|
||||
```
|
||||
|
||||
你需要将两个文件合并成第三个文件，后者同时包含前两个文件的内容。这种情况下，Parallel 需要访问两个文件，使用 `-I%` 变量的方式不符合本例的预期。
|
||||
|
||||
Parallel 默认情况下读取 1 个队列对象：
|
||||
```
|
||||
$ ls -1 | parallel echo
|
||||
ada
|
||||
lovelace
|
||||
richard
|
||||
stallman
|
||||
|
||||
```
|
||||
现在让 Parallel 每个任务使用 2 个队列对象：
|
||||
```
|
||||
$ ls -1 | parallel --max-args=2 echo
|
||||
ada lovelace
|
||||
richard stallman
|
||||
|
||||
```
|
||||
|
||||
现在，我们看到行已经并合并；具体而言，`ls -1` 的两个查询结果会被同时传送给 Parallel。传送给 Parallel 的参数涉及了任务所需的 2 个文件，但目前还只是 1 个有效参数：（对于两个任务分别为）"ada lovelace" 和 "richard stallman"。你真正需要的是每个任务对应 2 个独立的参数。
|
||||
|
||||
值得庆幸的是，Parallel 本身提供了上述所需的解析功能。如果你将 `--max-args` 设置为 `2`，那么 `{1}` 和 `{2}` 这两个变量分别代表传入参数的第一和第二部分：
|
||||
```
|
||||
$ ls -1 | parallel --max-args=2 cat {1} {2} ">" {1}_{2}.person
|
||||
|
||||
```
|
||||
|
||||
在上面的命令中，变量 `{1}` 值为 `ada` 或 `richard` （取决于你选取的任务），变量 `{2}` 值为 `lovelace` 或 `stallman`。通过使用重定向符号（放到引号中，防止被 Bash 识别，以便 Parallel 使用），（两个）文件的内容被分别重定向至新文件 `ada_lovelace.person` 和 `richard_stallman.person`。
|
||||
```
|
||||
$ ls -1
|
||||
ada
|
||||
ada_lovelace.person
|
||||
lovelace
|
||||
richard
|
||||
richard_stallman.person
|
||||
stallman
|
||||
|
||||
$ cat ada_*person
|
||||
ada lovelace
|
||||
$ cat ri*person
|
||||
richard stallman
|
||||
|
||||
```
|
||||
|
||||
如果你整天处理大量几百 MB 大小的日志文件，那么（上述）并行处理文本的方法对你帮忙很大；否则，上述例子只是个用于上手的示例。
|
||||
|
||||
然而，这种处理方法对于很多文本处理之外的操作也有很大帮助。下面是来自电影产业的真实案例，其中需要将一个目录中的视频文件和（对应的）音频文件进行合并。
|
||||
```
|
||||
$ ls -1
|
||||
12_LS_establishing-manor.avi
|
||||
12_wildsound.flac
|
||||
14_butler-dialogue-mixed.flac
|
||||
14_MS_butler.avi
|
||||
...略...
|
||||
|
||||
```
|
||||
|
||||
使用同样的方法，使用下面这个简单命令即可并行地合并文件：
|
||||
```
|
||||
$ ls -1 | parallel --max-args=2 ffmpeg -i {1} -i {2} -vcodec copy -acodec copy {1}.mkv
|
||||
|
||||
```
|
||||
|
||||
### 简单粗暴的方式
|
||||
|
||||
上述花哨的输入输出处理不一定对所有人的口味。如果你希望更直接一些，可以将一堆命令甩给 Parallel，然后去干些其它事情。
|
||||
|
||||
首先，需要创建一个文本文件，每行包含一个命令：
|
||||
```
|
||||
$ cat jobs2run
|
||||
bzip2 oldstuff.tar
|
||||
oggenc music.flac
|
||||
opusenc ambiance.wav
|
||||
convert bigfile.tiff small.jpeg
|
||||
ffmepg -i foo.avi -v:b 12000k foo.mp4
|
||||
xsltproc --output build/tmp.fo style/dm.xsl src/tmp.xml
|
||||
bzip2 archive.tar
|
||||
|
||||
```
|
||||
|
||||
接着，将文件传递给 Parallel：
|
||||
```
|
||||
$ parallel --jobs 6 < jobs2run
|
||||
|
||||
```
|
||||
|
||||
现在文件中对应的全部任务都在被 Parallel 执行。如果任务数量超过允许的数目（译者注：应该是 --jobs 指定的数目或默认值），Parallel 会创建并维护一个队列，直到任务全部完成。
|
||||
|
||||
### 更多内容
|
||||
|
||||
GNU Parallel 是个强大而灵活的工具，还有很多很多用例无法在本文中讲述。工具的 man 页面提供很多非常酷的例子可供你参考，包括通过 SSH 远程执行和在 Parallel 命令中使用 Bash 函数等。[YouTube][2] 上甚至有一个系列，包含大量操作演示，让你可以直接从 GNU Parallel 团队学习。GNU Paralle 的主要维护者还发布了官方使用指导手册，可以从 [Lulu.com][3] 获取。
|
||||
|
||||
GNU Parallel 有可能改变你完成计算的方式；即使没有，也会至少改变你主机花在计算上的时间。马上上手试试吧！
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/5/gnu-parallel
|
||||
|
||||
作者：[Seth Kenlon][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[pinewall](https://github.com/pinewall)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/seth
|
||||
[1]:https://www.gnu.org/software/parallel
|
||||
[2]:https://www.youtube.com/watch?v=OpaiGYxkSuQ&list=PL284C9FF2488BC6D1
|
||||
[3]:http://www.lulu.com/shop/ole-tange/gnu-parallel-2018/paperback/product-23558902.html
|
||||
@ -1,47 +0,0 @@
|
||||
LikeCoin，一种给创作者的开放内容许可的加密货币
|
||||
======
|
||||
|
||||
|
||||
传统观点表明，作家、摄影师、艺术家和其他创作者在 Creative Commons 和其他开放许可下免费共享内容的不会得到报酬。这意味着大多数独立创作者无法通过在互联网上发布他们的作品来赚钱。输入 [LikeCoin][1]：一个新的开源项目，旨在制定这个惯例，艺术家经常为了分发而不得不妥协或牺牲，这是过去的事情。
|
||||
|
||||
LikeCoin 协议旨在通过创意内容获利，因此创作者可以专注于创造出色的内容而不是出售。
|
||||
|
||||
协议同样基于去中心化技术，它可以跟踪何时使用内容，并使用 LikeCoin，一种 [Ethereum ERC-20][2] 加密货币令牌奖励其创作者。它通过“创造性证明”算法进行操作，该算法一部分根据作品收到多少个“喜欢”，一部分根据有多少作品衍生自它而分配 LikeCoin。由于开放授权内容有更多机会被重复使用并获得 LikeCoin 令牌，因此系统鼓励内容创作者在 Creative Commons 许可下发布。
|
||||
|
||||
### 如何运行
|
||||
|
||||
当通过 LikeCoin 协议上传创意片段时，内容创作者将包括作品的元数据，包括作者信息及其 InterPlanetary 关联数据（[IPLD][3]）。这些数据构成了衍生作品的家族图表;我们称作品与其衍生品之间的关系为“内容足迹”。这种结构使得内容的继承树可以很容易地追溯到原始作品。
|
||||
|
||||
LikeCoin 令牌将作品衍生历史记录的信息分发给创作者。由于所有创意作品都包含作者钱包的元数据，因此相应的 LikeCoin 份额可以通过算法计算并分发。
|
||||
|
||||
LikeCoin 可以通过两种方式获得奖励：直接由想要通过支付内容创建者来表示赞赏的个人或通过 Creators Pool 收集观众的“赞”的并根据内容的 LikeRank 分配 LikeCoin。基于在 LikeCoin 协议中的内容追踪，LikeRank 衡量作品重要性（或者我们在这定义的创造性）。一般来说，一副作品有越多的衍生作品，创意内容的创新越多，内容就会有更高的 LikeRank。 LikeRank 是内容创新性的量化者。
|
||||
|
||||
### 如何参与？
|
||||
|
||||
LikeCoin 仍然非常新，我们期望在 2018 年晚些时候推出我们的第一个去中心化程序来奖励 Creative Commons 的内容，并与更大的社区无缝连接。
|
||||
|
||||
LikeCoin 的大部分代码都可以在 [LikeCoin GitHub][4] 仓库中通过[ GPL 3.0 许可证][5]访问。由于它仍处于积极开发阶段，一些实验代码尚未公开，但我们会尽快完成。
|
||||
|
||||
我们欢迎功能请求，pull request，fork 和 star。请参与我们在 Github 上的开发，并加入我们在 [Telegram][6] 的讨论组。我们同样在 [Medium][7]、[Facebook][8]、[Twitter][9] 和我们的网站 [like.co][1] 发布关于我们进展的最新消息。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/5/likecoin
|
||||
|
||||
作者：[Kin Ko][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://opensource.com/users/ckxpress
|
||||
[1]:https://like.co/
|
||||
[2]:https://en.wikipedia.org/wiki/ERC20
|
||||
[3]:https://ipld.io/
|
||||
[4]:https://github.com/likecoin
|
||||
[5]:https://www.gnu.org/licenses/gpl-3.0.en.html
|
||||
[6]:https://t.me/likecoin
|
||||
[7]:http://medium.com/likecoin
|
||||
[8]:http://fb.com/likecoin.foundation
|
||||
[9]:https://twitter.com/likecoin_fdn
|
||||
@ -0,0 +1,55 @@
|
||||
如何在 Linux 中找到你的 IP 地址
|
||||
======
|
||||
|
||||
互联网协议（IP）不需要介绍 - 我们每天都在使用它。即使你不直接使用它，当你在浏览器上输入 website-name.com 时，它会查找该 URL 的 IP 地址，然后加载该网站。
|
||||
|
||||
我们将 IP 地址分为两类：私有和公共。私有 IP 地址是你的无线路由（和公司内网）提供的私有 IP 地址。它们的范围是 10.xxx、172.16.xx-172.31.xx 和 192.168.xx，其中 x=0 到 255。公有 IP 地址，顾名思义，是“公共”的，你可以在世界上任何地方访问它。每个网站都有一个唯一的 IP 地址，任何人可在任何地点访问，这可被视为公共 IP 地址。
|
||||
|
||||
此外，还有两种类型的 IP 地址：IPv4 和 IPv6。
|
||||
|
||||
IPv4 地址格式为 x.x.x.x，其中 x=0 到 255。有 2^32（大约 40 亿个）可能的 IPv4 地址。
|
||||
|
||||
IPv6 地址使用更复杂的十六进制。总的比特数是 128，这意味着有 2^128-340 后面有 36 个零！ - 可能的 IPv6 地址。IPv6 已经被引入解决了可预见的 IPv4 地址耗尽问题。
|
||||
|
||||
作为网络工程师，我建议不要与任何人共享你机器的公有 IP 地址。你的 WiFi 路由器有公共 IP，即 WAN（广域网）IP 地址，并且连接到该 WiFi 的任何设备都是相同的。连接到相同 WiFi 的所有设备都有上面所说的私有 IP 地址。例如，我的笔记本电脑的 IP 地址 192.168.0.5，而我的电话是 192.168.0.8。这些是私有 IP 地址，但两者都有相同的公有 IP 地址。
|
||||
|
||||
以下命令将列出IP地址列表，以查找你计算机的公有 IP 地址：
|
||||
|
||||
1. `ifconfig.me`
|
||||
2. `curl -4/-6 icanhazip.com`
|
||||
3. `curl ipinfo.io/ip`
|
||||
4. `curl api.ipify.org`
|
||||
5. `curl checkip.dyndns.org`
|
||||
6. `dig +short myip.opendns.com @resolver1.opendns.com`
|
||||
7. `host myip.opendns.com resolver1.opendns.com`
|
||||
8. `curl ident.me`
|
||||
9. `curl bot.whatismyipaddress.com`
|
||||
10. `curl ipecho.net/plain`
|
||||
|
||||
|
||||
|
||||
以下命令将为你提供接口的私有 IP 地址：
|
||||
|
||||
1. `ifconfig -a`
|
||||
2. `ip addr (ip a)`
|
||||
3. `hostname -I | awk ‘{print $1}’`
|
||||
4. `ip route get 1.2.3.4 | awk '{print $7}'`
|
||||
5. `(Fedora) Wifi-Settings→ click the setting icon next to the Wifi name that you are connected to → Ipv4 and Ipv6 both can be seen`
|
||||
6. `nmcli -p device show`
|
||||
|
||||
|
||||
|
||||
_注意：一些工具需要根据你正在使用的 Linux 发行版安装在你的系统上。另外，一些提到的命令使用第三方网站来获取 IP_
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/5/how-find-ip-address-linux
|
||||
|
||||
作者：[Archit Modi][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[geekpi](https://github.com/geekpi)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://opensource.com/users/architmodi
|
||||
Loading…
Reference in New Issue
Block a user