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Kevin Sicong Jiang
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在 RHEL/CentOS 7.0 中安装 LAMP（Linux、 Apache、 MariaDB、 PHP/PhpMyAdmin）
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================================================================================
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跳过 LAMP 的介绍，因为我认为你们大多数已经知道了。这个教程会集中在如何在升级到 Apache 2.4 的 Red Hat Enterprise Linux 7.0 和 CentOS 7.0 中安装和配置 LAMP：Linux、Apache、 MariaDB、 PHP/PhpMyAdmin。
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*在 RHEL/CentOS 7.0 中安装 LAMP*
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#### 前置要求 ####
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根据使用的发行版是 RHEL 还是 CentOS 7.0，按照下面的链接来进行最小化的系统安装，网络使用静态 IP。
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**对于 RHEL 7.0**
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- [RHEL 7.0 安装过程][1]
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- [在 RHEL 7.0 中注册和启用订阅仓库][2]
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**对于 CentOS 7.0**
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- [CentOS 7.0 安装过程][3]
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### 第一步：使用基本配置安装apache ###
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1、在完成最小化系统安装，并[在 RHEL/CentOS 7.0 上配置静态 IP][4] 后，就可以使用下面的命令从官方仓库安装最新的 Apache 2.4 httpd 服务了。
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# yum install httpd
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*安装 apache 服务*
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2、安装完成后，使用下面的命令来管理apache守护进程，因为 RHEL 和 CentOS 7.0 都将 init 脚本从 SysV 升级到了systemd，所以同时你还可以使用 SysV 脚本和 Apache 脚本来管理服务。
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# systemctl status|start|stop|restart|reload httpd
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或者
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# service httpd status|start|stop|restart|reload
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或者
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# apachectl configtest| graceful
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*启动apache服务*
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3、在使用 systemd 初始化脚本来启动 apache 服务后，要用 `firewall-cmd` 打开 RHEL/CentOS 7.0 防火墙规则， 这是通过 [firewalld][7] 守护进程管理 iptables 的默认命令。**
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# firewall-cmd --add-service=http
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**注意**：上面的命令会在系统重启或者 firewalld 服务重启后失效，因为它是即时的规则，它不会永久生效。要使 iptables 规则在 fiewalld 中持久化，使用 `--permanent` 选项并重启 firewalld 服务来生效。（LCTT 译注：也可以不重启 firewalld 服务，而是再执行一遍不带 ` --permanent` 选项的命令。）
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# firewall-cmd --permanent --add-service=http
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# systemctl restart firewalld
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*在 CentOS 7 中启用防火墙*
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下面是 firewalld 其他的重要选项：
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# firewall-cmd --state
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# firewall-cmd --list-all
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# firewall-cmd --list-interfaces
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# firewall-cmd --get-service
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# firewall-cmd --query-service service_name
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# firewall-cmd --add-port=8080/tcp
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4、要验证 apache 的功能，打开一个远程浏览器并使用 http 协议访问你服务器的 IP 地址(http://server_IP)， 应该会显示下图中的默认页面。
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*Apache 默认页*
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5、现在 apache 的根地址在 `/var/www/html`，该目录中没有提供任何索引文件。如果你想要看见根目录下的文件夹列表，打开 apache 欢迎配置文件并设置 `<LocationMach>` 下 `Indexes` 前的状态从`-`到`+`，下面的截图就是一个例子。
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# nano /etc/httpd/conf.d/welcome.conf
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*Apache 目录列出*
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6、关闭文件，重启 apache 服务来使设置生效，重载页面来看最终效果。
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# systemctl restart httpd
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*Apache 索引文件*
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### 第二步：为 Apache 安装 php5 支持 ###
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7、在为 apache 安装 php 支持之前，使用下面的命令的得到所有可用的php模块和扩展。
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# yum search php
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在 CentOS 7 上安装 PHP*
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8、根据你所要使用的应用类型，安装上述列表中所需的 PHP 模块。对于 PHP 中的基本的 MariaDB 支持和 PhpMyAdmin，你需要安装如下模块。
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# yum install php php-mysql php-pdo php-gd php-mbstring
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*安装 PHP 模块*
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*安装 PHP mbstring 模块*
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9、 要在你的浏览器上显示 PHP 的全部信息，用 root 账号执行如下命令在 Apache 的文档根目录下创建一个 `info.php` 文件，然后重启 httpd 服务，并在你的浏览器里面访问 http://server_IP/info.php 。
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# echo "<?php phpinfo(); ?>" > /var/www/html/info.php
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# systemctl restart httpd
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*查看 CentOS 7 上的 PHP 信息*
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10、如果你得到一个 PHP 的日期和时区错误，打开配置文件 `php.ini`，取消 `date.timezone` 语句的注释，加上你的实际时区参数，然后重启 Apache 守护进程。
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# nano /etc/php.ini
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找到并如下修改`date.timezone`，参考 [PHP 支持的时区列表][5]。（LCTT 译注：对于中国，可以使用 Asia/Shanghai、Asia/Chongqing 等，但是不建议使用向后兼容而保留的 PRC。）
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date.timezone = Continent/City
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*设置 PHP 的时区*
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###第三步：安装和配置 MariaDB 数据库 ###
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11、 Red Hat Enterprise Linux/CentOS 7.0 使用 MariaDB 替换 MySQL 为默认数据库管理系统。使用如下命令安装 MariaDB 数据库。
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# yum install mariadb-server mariadb
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*在 CentOS 7中安装 MariaDB*
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12、安装 MariaDB 后，启动数据库守护进程并使用 mysql_secure_installation 脚本来保护数据库（设置数据库的 root 密码、禁止远程 root 登录、移除测试数据库、移除匿名用户等）。
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# systemctl start mariadb
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# mysql_secure_installation
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*启动 MariaDB 数据库*
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*MariaDB 安全设置*
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13、要测试数据库功能，使用 root 账户登录 MariaDB 并用 quit 退出。
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mysql -u root -p
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MariaDB > SHOW VARIABLES;
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MariaDB > quit
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*连接 MariaDB 数据库*
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### 第四步：安装 PhpMyAdmin ###
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14、 RHEL 7.0 或者 CentOS 7.0 仓库默认没有提供 PhpMyAdmin 二进制安装包。如果你不适应使用 MySQL 命令行来管理你的数据库，你可以通过下面的命令启用 CentOS 7.0 rpmforge 仓库来安装 PhpMyAdmin。
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# yum install http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.3-1.el7.rf.x86_64.rpm
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启用 rpmforge 仓库后，下面安装 PhpMyAdmin。
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# yum install phpmyadmin
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*启用 RPMForge 仓库*
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15、下面配置 PhpMyAdmin 的 `phpmyadmin.conf` 来允许远程连接，它位于 Apache 的 `conf.d` 目录下，并注释掉下面的行。
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# nano /etc/httpd/conf.d/phpmyadmin.conf
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使用#来注释掉下列行。
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# Order Deny,Allow
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# Deny from all
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# Allow from 127.0.0.1
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*允许远程 PhpMyAdmin 访问*
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16、 要使用 cookie 验证来登录 PhpMyAdmin，像下面的截图那样使用[生成的秘密字符串][6]来添加一个 blowfish 字符串到 `config.inc.php` 文件中，重启 apache 服务并打开 URL：http://server_IP/phpmyadmin/。
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# nano /etc/httpd/conf.d/phpmyadmin.conf
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# systemctl restart httpd
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*在 PhpMyAdmin 中添加 Blowfish*
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*PhpMyAdmin 面板*
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### 第五步：在系统范围内启用 LAMP ###
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17、 如果你需要在重启后自动运行 MariaDB 和 Apache 服务，你需要在系统级地启用它们。
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# systemctl enable mariadb
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# systemctl enable httpd
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*系统级启用服务*
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这就是在 Red Hat Enterprise 7.0 或者 CentOS 7.0 中安装 LAMP 的过程。在 CentOS/RHEL 7.0 上关于 LAMP 的系列文章接下来将会讨论在 Apache 中创建虚拟主机，生成 SSL 证书、密钥和添加 SSL 事务支持。
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--------------------------------------------------------------------------------
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via: http://www.tecmint.com/install-lamp-in-centos-7/
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作者：[Matei Cezar][a]
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译者：[geekpi](https://github.com/geekpi)
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校对：[wxy](https://github.com/wxy)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]:http://www.tecmint.com/author/cezarmatei/
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[1]:http://www.tecmint.com/redhat-enterprise-linux-7-installation/
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[2]:http://www.tecmint.com/enable-redhat-subscription-reposiories-and-updates-for-rhel-7/
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[3]:http://www.tecmint.com/centos-7-installation/
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[4]:https://linux.cn/article-3977-1.html
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[5]:http://php.net/manual/en/timezones.php
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[6]:http://www.question-defense.com/tools/phpmyadmin-blowfish-secret-generator
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[7]:https://linux.cn/article-4425-1.html
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@ -0,0 +1,33 @@
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Linus Torvalds Says People Who Believe in AI Singularity Are on Drugs
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================================================================================
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*As usual, his comments should not be taken literally*
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**AI is a very hot topic right now, and many high profile people, including Elon Musk, the head of Tesla, have said that we're going to get sentient AIs soon and that it's going to be a dangerous threshold. It seems that Linus Torvalds doesn't feel the same way, and he thinks that it's just bad Sci-Fi.**
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The idea of AIs turning on their human creators is not something new, but recently the so-called AI singularity has been discussed, and people like Elon Musk and Stephen Hawking expressed concerns about the possibility of creating a monster. And it's not just them, forums and comments sections are full of alarmist people who don't know what to believe or who take for granted the opinions of much smarter people.
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As it turns out, Linus Torvalds, the creator of the Linux project, has a completely different opinion on this matter. In fact, he says that nothing like this will happen, and we have a much better reason to believe him. AI means that someone wrote its code, and Linus knows the power and the obstacles of writing an AI code. He's much likely to guess what's involved and to understands why an AI won't be a threat.
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### Linus Torvalds and AIs ###
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Linus Torvalds answered some questions from the community on [slashdot.org][1], and all his ideas were very interesting. He talked about the [future of gaming and Valve][2], but he also tackled stuff like AI. He's usually asked stuff about the kernel or open source, but he has opinions on other topics as well. As a matter a fact, the AI subject is something that he can actually talk about as a programmer.
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"So I'd expect just more of (and much fancier) rather targeted AI, rather than anything human-like at all. Language recognition, pattern recognition, things like that. I just don't see the situation where you suddenly have some existential crisis because your dishwasher is starting to discuss Sartre with you. The whole 'Singularity' kind of event? Yeah, it's science fiction, and not very good Sci-Fi at that, in my opinion. Unending exponential growth? What drugs are those people on? I mean, really" wrote Linus on Slashdot.
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It's your choice whether to believe Elon Musk or Linus, but if betting were involved, I would put my money on Linus.
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--------------------------------------------------------------------------------
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via: http://news.softpedia.com/news/linus-torvalds-says-people-who-believe-in-an-ai-singularity-are-on-drugs-486373.shtml
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作者：[Silviu Stahie][a]
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译者：[译者ID](https://github.com/译者ID)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]:http://news.softpedia.com/editors/browse/silviu-stahie
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[1]:http://classic.slashdot.org/story/15/06/30/0058243
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[2]:http://news.softpedia.com/news/linus-torvalds-said-valve-is-exploring-a-second-source-against-microsoft-486266.shtml
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@ -0,0 +1,184 @@
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Interviews: Linus Torvalds Answers Your Question
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================================================================================
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Last Thursday you had a chance to [ask Linus Torvalds][1] about programming, hardware, and all things Linux. You can read his answers to those questions below. If you'd like to see what he had to say the last time we sat down with him, [you can do so here][2].
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**Productivity**
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by DoofusOfDeath
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> You've somehow managed to originate two insanely useful pieces of software: Linux, and Git. Do you think there's anything in your work habits, your approach to choosing projects, etc., that have helped you achieve that level of productivity? Or is it just the traditional combination of talent, effort, and luck?
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**Linus**: I'm sure it's pretty much always that "talent, effort and luck". I'll leave it to others to debate how much of each...
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I'd love to point out some magical work habit that makes it all happen, but I doubt there really is any. Especially as the work habits I had wrt the kernel and Git have been so different.
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With Git, I think it was a lot about coming at a problem with fresh eyes (not having ever really bought into the traditional SCM mindset), and really trying to think about the issues, and spending a fair amount of time thinking about what the real problems were and what I wanted the design to be. And then the initial self-hosting code took about a day to write (ok, that was "self-hosting" in only the weakest sense, but still).
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And with Linux, obviously, things were very different - the big designs came from the outside, and it took half a year to host itself, and it hadn't even started out as a kernel to begin with. Clearly not a lot of thinking ahead and planning involved ;). So very different circumstances indeed.
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What both the kernel and Git have, and what I think is really important (and I guess that counts as a "work habit"), is a maintainer that stuck to it, and was responsive, responsible and sane. Too many projects falter because they don't have people that stick with them, or have people who have an agenda that doesn't match reality or the user expectations.
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But it's very important to point out that for Git, that maintainer was not me. Junio Hamano really should get pretty much all the credit for Git. Credit where credit is due. I'll take credit for the initial implementation and design of Git - it may not be perfect, but ten years on it still is very solid and very clearly the same basic design. But I'll take even _more_ credit for recognizing that Junio had his head screwed on right, and was the person to drive the project. And all the rest of the credit goes to him.
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Of course, that kind of segues into something else the kernel and Git do have in common: while I still maintain the kernel, I did end up finding a lot of smart people to maintain all the different parts of it. So while one important work habit is that "stick to it" persistence that you need to really take a project from a not-quite-usable prototype to something bigger and better, another important work-habit is probably to also "let go" and not try to own and control the project too much. Let other people really help you - guide the process but don't get in their way.
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**init system**
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by lorinc
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> There wasn't a decent unix-like kernel, you wrote one which ultimately became the most used. There wasn't a decent version control software, you wrote one which ultimately became the most love. Do you think we already have a decent init system, or do you have plan to write one that will ultimately settle the world on that hot topic?
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**Linus**: You can say the word "systemd", It's not a four-letter word. Seven letters. Count them.
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I have to say, I don't really get the hatred of systemd. I think it improves a lot on the state of init, and no, I don't see myself getting into that whole area.
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Yeah, it may have a few odd corners here and there, and I'm sure you'll find things to despise. That happens in every project. I'm not a huge fan of the binary logging, for example. But that's just an example. I much prefer systemd's infrastructure for starting services over traditional init, and I think that's a much bigger design decision.
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Yeah, I've had some personality issues with some of the maintainers, but that's about how you handle bug reports and accept blame (or not) for when things go wrong. If people thought that meant that I dislike systemd, I will have to disappoint you guys.
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**Can Valve change the Linux gaming market?**
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by Anonymous Coward
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> Do you think Valve is capable of making Linux a primary choice for gamers?
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**Linus**: "Primary"? Probably not where it's even aiming. I think consoles (and all those handheld and various mobile platforms that "real gamers" seem to dismiss as toys) are likely much more primary, and will stay so.
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I think Valve wants to make sure they can control their own future, and Linux and ValveOS is probably partly to explore a more "console-like" Valve experience (ie the whole "get a box set up for a single main purpose", as opposed to a more PC-like experience), and partly as a "second source" against Microsoft, who is a competitor in the console area. Keeping your infrastructure suppliers honest by making sure you have alternatives sounds like a good strategy, and particularly so when those suppliers may be competing with you directly elsewhere.
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So I don't think the aim is really "primary". "Solid alternative" is I think the aim. Of course, let's see where it goes after that.
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But I really have not been involved. People like Greg and the actual graphics driver guys have been in much more direct contact with Valve. I think it's great to see gaming on Linux, but at the same time, I'm personally not really much of a gamer.
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**The future of RT-Linux?**
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by nurhussein
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> According to Thomas Gleixner, [the future of the realtime patchset to Linux is in doubt][2], as it is difficult to secure funding from interested parties on this functionality even though it is both useful and important: What are your thoughts on this, and what do you think we need to do to get more support behind the RT patchset, especially considering Linux's increasing use in embedded systems where realtime functionality is undoubtedly useful.
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**Linus**: So I think this is one of those things where the markets decide how important rtLinux ends up being, and I suspect there are more than enough companies who end up wanting and using rtLinux that the project isn't really going anywhere. The complaints by Thomas were - I think - a wake-up call to the companies who end up wanting the extended hard realtime patches.
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So I suspect there are companies and groups like OSADL that end up funding and helping with rtLinux, and that it isn't going away.
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**Rigor and developments**
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by hcs_$reboot
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> The most complex program running on a machine is arguably its OS, especially the kernel. Linux (kernel) reached the top level in terms of performance, reliability and versatility. You have been criticized quite a few times for some virulent mails addressed to developers. Do you think Linux would be where it is without managing the project with an iron fist? To go further, do you think some other main OSS project would benefit from a more rigorous management approach?
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|
||||
**Linus**: One of the nice things about open source is how it allows people to really concentrate on what they are good at, and it has been a huge advantage for Linux that we've had people who are interested in the marketing side and selling Linux, as well as the legal side etc.
|
||||
|
||||
And that is all in addition, of course, to the original "we're motivated by the technology" people like me. And even within that "we're motivated by technology" group, you most certainly don't need to find _everything_ interesting, you can find the area you are passionate about and really care about and want to work on.
|
||||
|
||||
That's _fundamentally_ how open source works.
|
||||
|
||||
Now, if somebody is passionate about some "good management" thing, go wild, and try to get involved, and try to manage things. It's not what _I_ am interested in, but hey, the proof is in the pudding - anybody who thinks they have a new rigorous management approach that they think will help some part of the process, go wild.
|
||||
|
||||
Now, I personally suspect that it wouldn't work - not only are tech people an ornery lot to begin with (that whole "herding cats" thing), just look at all the crazy arguments on the internet. And ask yourself what actually holds an open source project like the kernel together? I think you need to be very oriented towards the purely technical solutions, simply because then you have tangible and real issues you can discuss (and argue about) with fairly clear-cut hard answers. It's the only thing people can really agree on in the big picture.
|
||||
|
||||
So the Linux approach to "management" has been to put technology first. That's rigorous enough for me. But as mentioned, it's a free-for-all. Anybody can come in and try to do better. Really.
|
||||
|
||||
And btw, it's worth noting that there are obviously specific smaller development teams where other management models work fine. Most of the individual developers are parts of teams inside particular companies, and within the confines of that company, there may well be a very strict rigorous management model. Similarly, within the confines of a particular productization effort there may be particular goals and models for that particular team that transcend that general "technical issues" thing.
|
||||
|
||||
Just to give a concrete example, the "development kernel" tree that I maintain works fundamentally differently and with very different rules from the "stable tree" that Greg does, which in turn is maintained very differently from what a distribution team within a Linux company does inside its maintenance kernel team.
|
||||
|
||||
So there's certainly room for different approaches to managing those very different groups. But do I think you can "rigorously manage" people on the internet? No.
|
||||
|
||||
**Functional languages?**
|
||||
by EmeraldBot
|
||||
|
||||
> While historically you've been a C and Assembly guy (and the odd shell scripting and such), what do you think of functional languages such as Lisp, Closure, Haskell, etc? Do you see any advantages to them, or do you view them as frivolous and impractical? If you decide to do so, thanks for taking the time to answer my question! You're a legend at what you do, and I think it's awesome that the significantly less interesting me can ask you a question like this.
|
||||
|
||||
**Linus**: I may be a fan of C (with a certain fondness for assembly, just because it's so close to the machine), but that's very much about a certain context. I work at a level where those languages make sense. I certainly don't think that tools like Haskell etc are "frivolous and impractical" in general, although on a kernel level (or in a source control management system) I suspect they kind of are.
|
||||
|
||||
Many moons ago I worked on sparse (the C parser and analyzer), and one of my coworkers was a Haskell fan, and did incredible example transformations in very simple (well, to him) code - stuff that is just nasty to write in C because it's pretty high-level, there's tons of memory management, and you're really talking about implementing fairly abstract and high-level rules with pattern matching etc.
|
||||
|
||||
So I'm definitely not a functional language kind of guy - it's not how I learnt programming, and it really isn't very relevant to what I do, and I wouldn't recognize Haskell code if it bit me in the ass and called me names. But no, I wouldn't call them frivolous.
|
||||
|
||||
**Critical software to the use of Linux**
|
||||
by TWX
|
||||
|
||||
> Mr. Torvalds, For many uses of Linux such as on the desktop, other software beyond the kernel and the base GNU tools are required. What other projects would you like to see given priority, and what would you like to see implemented or improved? Admittedly I thought most about X-Windows when asking this question; but I don't doubt that other daemons or systems can be just as important to the user experience. Thank you for your efforts all these years.
|
||||
|
||||
**Linus**: Hey, I don't really have any particular project I would want to champion, largely because we all have so different requirements on the desktop. There's just no single thing that stands out as being hugely more important than others to me.
|
||||
|
||||
What I do wish particularly desktop developers cared about is "consistency of experience". And by that I don't mean some kind of enforced visual consistency between different applications to make things "look coherent". No, I'm just talking about the pain and uncertainty users go through with upgrades, and understanding that while your project may be the most important project to *you* (because it's what you do), to your users, your project is likely just a fairly small and irrelevant part of their experience, and it's not very central at all, and they've learnt the quirks about that thing they don't even care about, and you really shouldn't break their expectations. Because it turns out that that is how you really make people hate their desktop.
|
||||
|
||||
This is not at all Linux-specific, of course - just look at the less than enthusiastic reception that other operating system redesigns have received. But I really wish that we hadn't had *both* of the major Linux desktop environments have to learn this (well, I hope they learnt) the hard way, and both of them ending up blaming their users rather than themselves.
|
||||
|
||||
**"anykernel"-style portable drivers?**
|
||||
by staalmannen
|
||||
|
||||
> What do you think about the "anykernel" concept (invented by another Finn btw) used in NetBSD? Basically, they have modularized the code so that a driver can be built either in a monolithic kernel or for user space without source code changes ( rumpkernel.org ). The drivers are highly portable and used in Genode os (L4 type kernels), minix etc... Would this be possible or desirable for Linux? Apparently there is one attempt called "libos"...
|
||||
|
||||
**Linus**: So I have bad experiences with "portable" drivers. Writing drivers to some common environment tends to force some ridiculously nasty impedance matching abstractions that just get in the way and make things really hard to read and modify. It gets particularly nasty when everybody ends up having complicated - and differently so - driver subsystems to handle a lot of commonalities for a certain class of drivers (say a network driver, or a USB driver), and the different operating systems really have very different approaches and locking rules etc.
|
||||
|
||||
I haven't seen anykernel drivers, but from past experience my reaction to "portable device drivers" is to run away, screaming like little girl. As they say in Swedish "Bränt barn luktar illa".
|
||||
|
||||
**Processor Architecture**
|
||||
by swv3752
|
||||
|
||||
> Several years ago, you were employed by Transmeta designing the Crusoe processor. I understand you are quite knowledgeable about cpu architecture. What are your thoughts on the Current Intel and AMD x86 CPUs particularly in comparison with ARM and IBM's Power8 CPUs? Where do you see the advantages of each one?
|
||||
|
||||
**Linus**: I'm no CPU architect, I just play one on TV.
|
||||
|
||||
But yes, I've been close to the CPU both as part of my kernel work, and as part of a processor company, and working at that level for a long time just means that you end up having fairly strong opinions. One of the things that my experiences at Transmeta convinced me of, for example, was that there's definitely very much a limit to what software should care about. I loved working at Transmeta, I loved the whole startup company environment, I loved working with really smart people, but in the end I ended up absolutely *not* loving to work with overly simple hardware (I also didn't love the whole IPO process, and what that did to the company culture, but that's a different thing).
|
||||
|
||||
Because there's only so much that software can do to compensate.
|
||||
|
||||
Something similar happened with my kernel work on the alpha architecture, which also started out as being an overly simplified implementation in the name of being small and supposedly running really fast. While I really started out liking the alpha architecture for being so clean, I ended up detesting how fragile the architecture implementations were (and by the time that got fixed in the 21264, I had given up on alpha).
|
||||
|
||||
So I've come to absolutely detest CPU's that need a lot of compiler smarts or special tuning to go fast. Life is too short to waste on in-order CPU's, or on hardware designers who think software should take care of the pieces that they find to be too complicated to handle themselves, and as a result just left undone. "Weak memory ordering" is just another example.
|
||||
|
||||
Thankfully, most of the industry these days seems to agree. Yes, there are still in-order cores, but nobody tries to make excuses for them any more: they are for the truly cheap and low-end market.
|
||||
|
||||
I tend to really like the modern Intel cores in particular, which tend to take that "let's not be stupid" really to heart. With the kernel being so threaded, I end up caring a lot about things like memory ordering etc, and the Intel big-core CPU's tend to be in a class of their own there. As a software person who cares about performance and looks at instruction profiles etc, it's just so *nice* to see that the CPU doesn't have some crazy glass jaw where you have to be very careful.
|
||||
|
||||
**GPU kernels**
|
||||
by maraist
|
||||
|
||||
> Is there any inspiration that a GPU based kernel / scheduler has for you? How might Linux be improved to better take advantage of GPU-type batch execution models. Given that you worked transmeta and JIT compiled host-targeted runtimes. GPUs 1,000-thread schedulers seem like the next great paradigm for the exact type of machines that Linux does best on.
|
||||
|
||||
**Linus**: I don't think we'll see the kernel ever treat GPU threads the way we treat CPU threads. Not with the current model of GPU's (and that model doesn't really seem to be changing all that much any more).
|
||||
|
||||
Yes, GPU's are getting much better, and now generally have virtual memory and the ability to preempt execution, and you could run an OS on them. But the scheduling latencies are pretty high, and the threads are not really "independent" (ie they tend to share a lot of state - like the virtual address space and a large shared register set), so GPU "threads" don't tend to work like CPU threads. You'd schedule them all-or-nothing, so if you were to switch processes, you'd treat the GPU as one entity where you switch all the threads at once.
|
||||
|
||||
So it really wouldn't look like a thousand threads to the kernel. The GPU would still be scheduled as one single entity (or maybe a couple of entities depending on how the GPU is partitioned). The fact that that single entity works by doing a lot of things in massive parallelism is kind of immaterial for the kernel that doesn't end up seeing that parallelism as separate threads.
|
||||
|
||||
**alleged danger of Artificial Intelligence**
|
||||
by peter303
|
||||
|
||||
> Some computer experts like Marvin Minsky, Larry Page, Ray Kuzweil think A.I. will be a great gift to Mankind. Others like Bill Joy and Elon Musk are fearful of potential danger. Where do you stand, Linus?
|
||||
|
||||
**Linus**: I just don't see the thing to be fearful of.
|
||||
|
||||
We'll get AI, and it will almost certainly be through something very much like recurrent neural networks. And the thing is, since that kind of AI will need training, it won't be "reliable" in the traditional computer sense. It's not the old rule-based prolog days, when people thought they'd *understand* what the actual decisions were in an AI.
|
||||
|
||||
And that all makes it very interesting, of course, but it also makes it hard to productize. Which will very much limit where you'll actually find those neural networks, and what kinds of network sizes and inputs and outputs they'll have.
|
||||
|
||||
So I'd expect just more of (and much fancier) rather targeted AI, rather than anything human-like at all. Language recognition, pattern recognition, things like that. I just don't see the situation where you suddenly have some existential crisis because your dishwasher is starting to discuss Sartre with you.
|
||||
|
||||
The whole "Singularity" kind of event? Yeah, it's science fiction, and not very good SciFi at that, in my opinion. Unending exponential growth? What drugs are those people on? I mean, really..
|
||||
|
||||
It's like Moore's law - yeah, it's very impressive when something can (almost) be plotted on an exponential curve for a long time. Very impressive indeed when it's over many decades. But it's _still_ just the beginning of the "S curve". Anybody who thinks any different is just deluding themselves. There are no unending exponentials.
|
||||
|
||||
**Is the kernel basically a finished project?**
|
||||
by NaCh0
|
||||
|
||||
> Aside from adding drivers and refactoring algorithms when performance limits are discovered, is there anything left for the kernel? Maybe it's a failure of tech journalism but we never hear about the next big thing in kernel land anymore.
|
||||
|
||||
**Linus**: I don't think there's much of a "next big thing" in the kernel.
|
||||
|
||||
I wouldn't say that there is nothing but drivers (and architectures are kind of "CPU drivers) and improving scalability left, because I'm constantly amazed by how many new things people figure out are still good ideas. But they tend to still be pretty incremental improvements. An OS kernel doesn't look *that* radically different from what it was 40 years ago, and that's fine. I think radical new ideas are often overrated, and the thing that really matters in the end is that plodding detail work. That's how technology evolves.
|
||||
|
||||
And judging by how our kernel releases are going, there's no end in sight for that "plodding detail work". And it's still as interesting as it ever was.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://linux.slashdot.org/story/15/06/30/0058243/interviews-linus-torvalds-answers-your-question
|
||||
|
||||
作者：[samzenpus][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) 原创翻译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:samzenpus@slashdot.org
|
||||
[1]:http://interviews.slashdot.org/story/15/06/24/1718247/interview-ask-linus-torvalds-a-question
|
||||
[2]:http://meta.slashdot.org/story/12/10/11/0030249/linus-torvalds-answers-your-questions
|
||||
[3]:https://lwn.net/Articles/604695/
|
||||
@ -0,0 +1,79 @@
|
||||
7 command line tools for monitoring your Linux system
|
||||
================================================================================
|
||||
**Here is a selection of basic command line tools that will make your exploration and optimization in Linux easier. **
|
||||
|
||||
|
||||
|
||||
### Dive on in ###
|
||||
|
||||
One of the great things about Linux is how deeply you can dive into the system to explore how it works and to look for opportunities to fine tune performance or diagnose problems. Here is a selection of basic command line tools that will make your exploration and optimization easier. Most of these commands are already built into your Linux system, but in case they aren’t, just Google “install”, the command name, and the name of your distro and you’ll find which package needs installing (note that some commands are bundled with other commands in a package that has a different name from the one you’re looking for). If you have any other tools you use, let me know for our next Linux Tools roundup.
|
||||
|
||||
|
||||
|
||||
### How we did it ###
|
||||
|
||||
FYI: The screenshots in this collection were created on [Debian Linux 8.1][1] (“Jessie”) running in a virtual machine under [Oracle VirtualBox 4.3.28][2] under [OS X 10.10.3][3] (“Yosemite”). See my next slideshow “[How to install Debian Linux in a VirtualBox VM][4]” for a tutorial on how to build your own Debian VM.
|
||||
|
||||
|
||||
|
||||
### Top command ###
|
||||
|
||||
One of the simpler Linux system monitoring tools, the **top command** comes with pretty much every flavor of Linux. This is the default display, but pressing the “z” key switches the display to color. Other hot keys and command line switches control things such as the display of summary and memory information (the second through fourth lines), sorting the list according to various criteria, killing tasks, and so on (you can find the complete list at [here][5]).
|
||||
|
||||
|
||||
|
||||
### htop ###
|
||||
|
||||
Htop is a more sophisticated alternative to top. Wikipedia: “Users often deploy htop in cases where Unix top does not provide enough information about the systems processes, for example when trying to find minor memory leaks in applications. Htop is also popularly used interactively as a system monitor. Compared to top, it provides a more convenient, cursor-controlled interface for sending signals to processes.” (For more detail go [here][6].)
|
||||
|
||||
|
||||
|
||||
### Vmstat ###
|
||||
|
||||
Vmstat is a simpler tool for monitoring your Linux system performance statistics but that makes it highly suitable for use in shell scripts. Fire up your regex-fu and you can do some amazing things with vmstat and cron jobs. “The first report produced gives averages since the last reboot. Additional reports give information on a sampling period of length delay. The process and memory reports are instantaneous in either case” (go [here][7] for more info.).
|
||||
|
||||
|
||||
|
||||
### ps ###
|
||||
|
||||
The ps command shows a list of running processes. In this case, I’ve used the “-e”switch to show everything, that is, all processes running (I’ve scrolled back to the top of the output otherwise the column names wouldn’t be visible). This command has a lot of switches that allow you to format the output as needed. Add a little of the aforementioned regex-fu and you’ve got a powerful tool. Go [here][8] for the full details.
|
||||
|
||||
|
||||
|
||||
### Pstree ###
|
||||
|
||||
Pstree “shows running processes as a tree. The tree is rooted at either pid or init if pid is omitted. If a user name is specified, all process trees rooted at processes owned by that user are shown.”This is a really useful tool as the tree helps you sort out which process is dependent on which process (go [here][9]).
|
||||
|
||||
|
||||
|
||||
### pmap ###
|
||||
|
||||
Understanding just how an app uses memory is often crucial in debugging, and the pmap produces just such information when given a process ID (PID). The screenshot shows the medium weight output generated by using the “-x”switch. You can get pmap to produce even more detailed information using the “-X”switch but you’ll need a much wider terminal window.
|
||||
|
||||
|
||||
|
||||
### iostat ###
|
||||
|
||||
A crucial factor in your Linux system’s performance is processor and storage usage, which are what the iostat command reports on. As with the ps command, iostat has loads of switches that allow you to select the output format you need as well as sample performance over a time period and then repeat that sampling a number of times before reporting. See [here][10].
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://www.networkworld.com/article/2937219/linux/7-command-line-tools-for-monitoring-your-linux-system.html
|
||||
|
||||
作者：[Mark Gibbs][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) 原创翻译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://www.networkworld.com/author/Mark-Gibbs/
|
||||
[1]:https://www.debian.org/releases/stable/
|
||||
[2]:https://www.virtualbox.org/
|
||||
[3]:http://www.apple.com/osx/
|
||||
[4]:http://www.networkworld.com/article/2937148/how-to-install-debian-linux-8-1-in-a-virtualbox-vm
|
||||
[5]:http://linux.die.net/man/1/top
|
||||
[6]:http://linux.die.net/man/1/htop
|
||||
[7]:http://linuxcommand.org/man_pages/vmstat8.html
|
||||
[8]:http://linux.die.net/man/1/ps
|
||||
[9]:http://linux.die.net/man/1/pstree
|
||||
[10]:http://linux.die.net/man/1/iostat
|
||||
@ -0,0 +1,67 @@
|
||||
Install Google Hangouts Desktop Client In Linux
|
||||
================================================================================
|
||||
|
||||
|
||||
Earlier, we have seen how to [install Facebook Messenger in Linux][1] and [WhatsApp desktop client in Linux][2]. Both of these were unofficial apps. I have one more unofficial app for today and it is [Google Hangouts][3].
|
||||
|
||||
Of course, you can use Google Hangouts in the web browser but it is more fun to use the desktop client than the web browser one. Curious? Let’s see how to **install Google Hangouts desktop client in Linux** and how to use it.
|
||||
|
||||
### Install Google Hangouts in Linux ###
|
||||
|
||||
We are going to use an open source project called [yakyak][4] which is unofficial Google Hangouts client for Linux, Windows and OS X. I’ll show you how to use yakyak in Ubuntu but I believe that you can use the same method to use it in other Linux distributions. Before we see how to use it, let’s first take a look at main features of yakyak:
|
||||
|
||||
- Send and receive chat messages
|
||||
- Create and change conversations (rename, add people)
|
||||
- Leave and/or delete conversation
|
||||
- Desktop notifications
|
||||
- Toggle notifications on/off
|
||||
- Drag-drop, copy-paste or attach-button for image upload.
|
||||
- Hangupsbot sync room aware (actual user pics)
|
||||
- Shows inline images
|
||||
- History scrollback
|
||||
|
||||
Sounds good enough? Download the installation files from the link below:
|
||||
|
||||
- [Download Google Hangout client yakyak][5]
|
||||
|
||||
The downloaded file would be compressed. Extract it and you will see a directory like linux-x64 or linux-x32 based on your system. Go in to this directory and you should see a file named yakyak. Double click on it to run it.
|
||||
|
||||
|
||||
|
||||
You’ll have to enter your Google Account credentials of course.
|
||||
|
||||
|
||||
|
||||
Once you are through, you’ll see a screen like the one below where you can chat with your Google contacts.
|
||||
|
||||
|
||||
|
||||
If you want to show profile pictures of the contacts, you can select View->Show conversation thumbnails.
|
||||
|
||||
|
||||
|
||||
You’ll also get desktop notification for new messages.
|
||||
|
||||
|
||||
|
||||
### Worth a try? ###
|
||||
|
||||
I let you give it a try and decide whether or not it is worth to **install Google Hangouts client in Linux**. If you want official apps, take a look at these [instant messaging applications with native Linux clients][6]. Don’t forget to share your experience with Google Hangouts in Linux.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://itsfoss.com/install-google-hangouts-linux/
|
||||
|
||||
作者：[Abhishek][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) 原创翻译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://itsfoss.com/author/abhishek/
|
||||
[1]:http://itsfoss.com/facebook-messenger-linux/
|
||||
[2]:http://itsfoss.com/whatsapp-linux-desktop/
|
||||
[3]:http://www.google.com/+/learnmore/hangouts/
|
||||
[4]:https://github.com/yakyak/yakyak
|
||||
[5]:https://github.com/yakyak/yakyak
|
||||
[6]:http://itsfoss.com/best-messaging-apps-linux/
|
||||
@ -0,0 +1,36 @@
|
||||
Linux FAQs with Answers--How to fix “tar: Exiting with failure status due to previous errors”
|
||||
================================================================================
|
||||
> **Question**: When I try to create an archive using tar command, it fails in the middle, and throws an error saying: "tar: Exiting with failure status due to previous errors." What causes this error, and how can I solve this error?
|
||||
|
||||
|
||||
|
||||
If you encounter the following error while running tar command, the most likely reason is that you do not have read permission on one of the files you are trying to archive with tar.
|
||||
|
||||
tar: Exiting with failure status due to previous errors
|
||||
|
||||
Then how can we pin down the file(s) causing the errors, or identify any other cause?
|
||||
|
||||
The tar command should actually print out what those "previous errors" are, but you can easily miss printed error messages if you run tar in verbose mode (e.g., -cvf). To catch error messages more easily, you can filter out tar's stdout messages as follows.
|
||||
|
||||
$ tar cvzfz backup.tgz my_program/ > /dev/null
|
||||
|
||||
You will then see only error messages sent by tar to stderr.
|
||||
|
||||
tar: my_program/src/lib/.conf.db.~lock~: Cannot open: Permission denied
|
||||
tar: Exiting with failure status due to previous errors
|
||||
|
||||
As you can see in the above example, the cause for the errors is indeed "denied read permission."
|
||||
|
||||
To solve the problem, simply adjust the permission of the problematic file (or remove it), and re-run tar.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://ask.xmodulo.com/tar-exiting-with-failure-status-due-to-previous-errors.html
|
||||
|
||||
作者：[Dan Nanni][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) 原创翻译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://ask.xmodulo.com/author/nanni
|
||||
@ -0,0 +1,109 @@
|
||||
Linux FAQs with Answers--How to install a Brother printer on Linux
|
||||
================================================================================
|
||||
> **Question**: I have a Brother HL-2270DW laser printer, and want to print documents from my Linux box using this printer. How can I install an appropriate Brother printer driver on my Linux computer, and use it?
|
||||
|
||||
Brother is well known for its affordable [compact laser printer lineup][1]. You can get a high-quality WiFi/duplex-capable laser printer for less than 200USD, and the price keeps going down. On top of that, they provide reasonably good Linux support, so you can download and install their printer driver on your Linux computer. I bought [HL-2270DW][2] model more than a year ago, and I have been more than happy with its performance and reliability.
|
||||
|
||||
Here is how to install and configure a Brother printer driver on Linux. In this tutorial, I am demonstrating the installation of a USB driver for Brother HL-2270DW laser printer. So first connect your printer to a Linux computer via USB cable.
|
||||
|
||||
### Preparation ###
|
||||
|
||||
In this preparation step, go to the official [Brother support website][3], and search for the driver of your Brother printer by typing printer model name (e.g., HL-2270DW).
|
||||
|
||||
|
||||
|
||||
Once you go to the download page for your Brother printer, choose your Linux platform. For Debian, Ubuntu or their derivatives, choose "Linux (deb)". For Fedora, CentOS or RHEL, choose "Linux (rpm)".
|
||||
|
||||
|
||||
|
||||
On the next page, you will find a LPR driver as well as CUPS wrapper driver for your printer. The former is a command-line driver, while the latter allows you to configure and manage your printer via web-based administration interface. Especially the CUPS-based GUI is quite useful for (local or remote) printer maintenance. It is recommended that you install both drivers. So click on "Driver Install Tool" and download the installer file.
|
||||
|
||||
|
||||
|
||||
Before proceeding to run the installer file, you need to do one additional step if you are using a 64-bit Linux system.
|
||||
|
||||
Since Brother printer drivers are developed for 32-bit Linux, you need to install necessary 32-bit libraries on 64-bit Linux as follows.
|
||||
|
||||
On older Debian (6.0 or earlier) or Ubuntu (11.04 or earlier), install the following package.
|
||||
|
||||
$ sudo apt-get install ia32-libs
|
||||
|
||||
On newer Debian or Ubuntu which has introduced multiarch, you can install the following package instead:
|
||||
|
||||
$ sudo apt-get install lib32z1 lib32ncurses5
|
||||
|
||||
which replaces ia32-libs package. Or, you can install just:
|
||||
|
||||
$ sudo apt-get install lib32stdc++6
|
||||
|
||||
If you are using a Red Hat based Linux, you can install:
|
||||
|
||||
$ sudo yum install glibc.i686
|
||||
|
||||
### Driver Installation ###
|
||||
|
||||
Now go ahead and extract a downloaded driver installer file.
|
||||
|
||||
$ gunzip linux-brprinter-installer-2.0.0-1.gz
|
||||
|
||||
Next, run the driver installer file as follows.
|
||||
|
||||
$ sudo sh ./linux-brprinter-installer-2.0.0-1
|
||||
|
||||
You will be prompted to type a printer model name. Type the model name of your printer, for example "HL-2270DW".
|
||||
|
||||
|
||||
|
||||
After agreeing to GPL license agreement, accept default answers to any subsequent questions.
|
||||
|
||||
|
||||
|
||||
Now LPR/CUPS printer drivers are installed. Proceed to configure your printer next.
|
||||
|
||||
### Printer Configuration ###
|
||||
|
||||
We are going to configure and manage a Brother via CUPS-based web management interface.
|
||||
|
||||
First, verify that CUPS daemon is running successfully.
|
||||
|
||||
$ sudo netstat -nap | grep 631
|
||||
|
||||
Open a web browser window, and go to http://localhost:631. You will see the following CUPS printer management interface.
|
||||
|
||||
|
||||
|
||||
Go to "Administration" tab, and click on "Manage Printers" under Printers section.
|
||||
|
||||
|
||||
|
||||
You must see your printer (HL-2270DW) listed in the next page. Click on the printer name.
|
||||
|
||||
|
||||
In the dropdown menu titled "Administration", choose "Set As Server Default" option. This will make your printer system-wide default.
|
||||
|
||||
|
||||
|
||||
When asked to authenticate yourself, type in your Linux login information.
|
||||
|
||||
|
||||
|
||||
Now the basic configuration step is mostly done. To test print, open any document viewer application (e.g., PDF viwer), and print it. You will see "HL-2270DW" listed and chosen by default in printer setting.
|
||||
|
||||
|
||||
|
||||
Print should work now. You can see the printer status and manage printer jobs via the same CUPS web interface.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://ask.xmodulo.com/install-brother-printer-linux.html
|
||||
|
||||
作者：[Dan Nanni][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) 原创翻译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://ask.xmodulo.com/author/nanni
|
||||
[1]:http://xmodulo.com/go/brother_printers
|
||||
[2]:http://xmodulo.com/go/hl_2270dw
|
||||
[3]:http://support.brother.com/
|
||||
@ -0,0 +1,38 @@
|
||||
Linux FAQs with Answers--How to open multiple tabs in a GNOME terminal on Ubuntu 15.04
|
||||
================================================================================
|
||||
> **Question**: I used to be able to open multiple tabs inside gnome-terminal on my Ubuntu desktop. On Ubuntu 15.04, however, I can no longer open a new tab in my terminal window. How can I open tabs in gnome-terminal on Ubuntu 15.04?
|
||||
|
||||
On Ubuntu 14.10 or earlier, gnome-terminal allowed you to open either a new terminal or a tab inside a terminal window. However, starting with Ubuntu 15.04, gnome-terminal has removed "New Tab" menu option. This is actually not a bug, but a feature that attempts to unify new tab and new window. GNOME 3.12 has introduced a [single "Open Terminal" option][1]. The ability to open a new terminal tab has been migrated from the terminal menu to Preferences.
|
||||
|
||||
|
||||
|
||||
### Open Tabs via Preferences ###
|
||||
|
||||
To be able to open a new tab in new gnome-terminal of Ubuntu 15.04, go to "Edit" -> "Preferences", and change "Open new terminals in: Window" to "Open new terminals in: Tab".
|
||||
|
||||
|
||||
|
||||
Now if you open a new terminal via menu, it will automatically open a new tab inside the terminal.
|
||||
|
||||
|
||||
|
||||
### Open Tabs via a Keyboard Shortcut ###
|
||||
|
||||
If you do not want to change Preferences, you can hold down <Ctrl> to "invert" Preferences setting temporarily. For example, under the default Preferences, if you hold down <Ctrl> and click on "New Terminal", it will open a new tab, not a terminal.
|
||||
|
||||
Alternatively, you can simply use a keyboard shortcut <Shift+Ctrl+T> to open a new tab in a terminal.
|
||||
|
||||
In my view, this UI change in gnome-terminal is not quite an improvement. For example, you are no longer able to customize the name of individual terminal tabs. This feature is useful when you have many tabs open in a terminal. With the default tab name fixed to the current prompt (whose length can grow quickly), you easily cannot see the whole prompt string in the limited tab name space. Hope this feature will become available soon.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://ask.xmodulo.com/open-multiple-tabs-gnome-terminal-ubuntu.html
|
||||
|
||||
作者：[Dan Nanni][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) 原创翻译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://ask.xmodulo.com/author/nanni
|
||||
[1]:http://worldofgnome.org/opening-a-new-terminal-tabwindow-in-gnome-3-12/
|
||||
@ -0,0 +1,115 @@
|
||||
wyangsun 翻译中
|
||||
Why is the ibdata1 file continuously growing in MySQL?
|
||||
================================================================================
|
||||
|
||||
|
||||
We receive this question about the ibdata1 file in MySQL very often in [Percona Support][1].
|
||||
|
||||
The panic starts when the monitoring server sends an alert about the storage of the MySQL server – saying that the disk is about to get filled.
|
||||
|
||||
After some research you realize that most of the disk space is used by the InnoDB’s shared tablespace ibdata1. You have [innodb_file_per_table][2] enabled, so the question is:
|
||||
|
||||
### What is stored in ibdata1? ###
|
||||
|
||||
When you have innodb_file_per_table enabled, the tables are stored in their own tablespace but the shared tablespace is still used to store other InnoDB’s internal data:
|
||||
|
||||
- data dictionary aka metadata of InnoDB tables
|
||||
- change buffer
|
||||
- doublewrite buffer
|
||||
- undo logs
|
||||
|
||||
Some of them can be configured on [Percona Server][3] to avoid becoming too large. For example you can set a maximum size for change buffer with [innodb_ibuf_max_size][4] or store the doublewrite buffer on a separate file with [innodb_doublewrite_file][5].
|
||||
|
||||
In MySQL 5.6 you can also create external UNDO tablespaces so they will be in their own files instead of stored inside ibdata1. Check following [documentation link][6].
|
||||
|
||||
### What is causing the ibdata1 to grow that fast? ###
|
||||
|
||||
Usually the first command that we need to run when there is a MySQL problem is:
|
||||
|
||||
SHOW ENGINE INNODB STATUSG
|
||||
|
||||
That will show us very valuable information. We start checking the **TRANSACTIONS** section and we find this:
|
||||
|
||||
---TRANSACTION 36E, ACTIVE 1256288 sec
|
||||
MySQL thread id 42, OS thread handle 0x7f8baaccc700, query id 7900290 localhost root
|
||||
show engine innodb status
|
||||
Trx read view will not see trx with id >= 36F, sees < 36F
|
||||
|
||||
This is the most common reason, a pretty old transaction created 14 days ago. The status is **ACTIVE**, that means InnoDB has created a snapshot of the data so it needs to maintain old pages in **undo** to be able to provide a consistent view of the database since that transaction was started. If your database is heavily write loaded that means lots of undo pages are being stored.
|
||||
|
||||
If you don’t find any long-running transaction you can also monitor another variable from the INNODB STATUS, the “**History list length.**” It shows the number of pending purge operations. In this case the problem is usually caused because the purge thread (or master thread in older versions) is not capable to process undo records with the same speed as they come in.
|
||||
|
||||
### How can I check what is being stored in the ibdata1? ###
|
||||
|
||||
Unfortunately MySQL doesn’t provide information of what is being stored on that ibdata1 shared tablespace but there are two tools that will be very helpful. First a modified version of innochecksum made by Mark Callaghan and published in [this bug report][7].
|
||||
|
||||
It is pretty easy to use:
|
||||
|
||||
# ./innochecksum /var/lib/mysql/ibdata1
|
||||
0 bad checksum
|
||||
13 FIL_PAGE_INDEX
|
||||
19272 FIL_PAGE_UNDO_LOG
|
||||
230 FIL_PAGE_INODE
|
||||
1 FIL_PAGE_IBUF_FREE_LIST
|
||||
892 FIL_PAGE_TYPE_ALLOCATED
|
||||
2 FIL_PAGE_IBUF_BITMAP
|
||||
195 FIL_PAGE_TYPE_SYS
|
||||
1 FIL_PAGE_TYPE_TRX_SYS
|
||||
1 FIL_PAGE_TYPE_FSP_HDR
|
||||
1 FIL_PAGE_TYPE_XDES
|
||||
0 FIL_PAGE_TYPE_BLOB
|
||||
0 FIL_PAGE_TYPE_ZBLOB
|
||||
0 other
|
||||
3 max index_id
|
||||
|
||||
It has 19272 UNDO_LOG pages from a total of 20608. **That’s the 93% of the tablespace**.
|
||||
|
||||
The second way to check the content of a tablespace are the [InnoDB Ruby Tools][8] made by Jeremy Cole. It is a more advanced tool to examine the internals of InnoDB. For example we can use the space-summary parameter to get a list with every page and its data type. We can use standard Unix tools to get the number of **UNDO_LOG** pages:
|
||||
|
||||
# innodb_space -f /var/lib/mysql/ibdata1 space-summary | grep UNDO_LOG | wc -l
|
||||
19272
|
||||
|
||||
Altough in this particular case innochecksum is faster and easier to use I recommend you to play with Jeremy’s tools to learn more about the data distribution inside InnoDB and its internals.
|
||||
|
||||
OK, now we know where the problem is. The next question:
|
||||
|
||||
### How can I solve the problem? ###
|
||||
|
||||
The answer to this question is easy. If you can still commit that query, do it. If not you’ll have to kill the thread to start the rollback process. That will just stop ibdata1 from growing but it is clear that your software has a bug or someone made a mistake. Now that you know how to identify where is the problem you need to find who or what is causing it using your own debugging tools or the general query log.
|
||||
|
||||
If the problem is caused by the purge thread then the solution is usually to upgrade to a newer version where you can use a dedicated purge thread instead of the master thread. More information on the following [documentation link][9].
|
||||
|
||||
### Is there any way to recover the used space? ###
|
||||
|
||||
No, it is not possible at least in an easy and fast way. InnoDB tablespaces never shrink… see the following [10-year old bug report][10] recently updated by James Day (thanks):
|
||||
|
||||
When you delete some rows, the pages are marked as deleted to reuse later but the space is never recovered. The only way is to start the database with fresh ibdata1. To do that you would need to take a full logical backup with mysqldump. Then stop MySQL and remove all the databases, ib_logfile* and ibdata* files. When you start MySQL again it will create a new fresh shared tablespace. Then, recover the logical dump.
|
||||
|
||||
### Summary ###
|
||||
|
||||
When the ibdata1 file is growing too fast within MySQL it is usually caused by a long running transaction that we have forgotten about. Try to solve the problem as fast as possible (commiting or killing a transaction) because you won’t be able to recover the wasted disk space without the painfully slow mysqldump process.
|
||||
|
||||
Monitoring the database to avoid these kind of problems is also very recommended. Our [MySQL Monitoring Plugins][11] includes a Nagios script that can alert you if it finds a too old running transaction.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.percona.com/blog/2013/08/20/why-is-the-ibdata1-file-continuously-growing-in-mysql/
|
||||
|
||||
作者：[Miguel Angel Nieto][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) 原创翻译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://www.percona.com/blog/author/miguelangelnieto/
|
||||
[1]:https://www.percona.com/products/mysql-support
|
||||
[2]:http://dev.mysql.com/doc/refman/5.5/en/innodb-parameters.html#sysvar_innodb_file_per_table
|
||||
[3]:https://www.percona.com/software/percona-server
|
||||
[4]:https://www.percona.com/doc/percona-server/5.5/scalability/innodb_insert_buffer.html#innodb_ibuf_max_size
|
||||
[5]:https://www.percona.com/doc/percona-server/5.5/performance/innodb_doublewrite_path.html?id=percona-server:features:percona_innodb_doublewrite_path#innodb_doublewrite_file
|
||||
[6]:http://dev.mysql.com/doc/refman/5.6/en/innodb-performance.html#innodb-undo-tablespace
|
||||
[7]:http://bugs.mysql.com/bug.php?id=57611
|
||||
[8]:https://github.com/jeremycole/innodb_ruby
|
||||
[9]:http://dev.mysql.com/doc/innodb/1.1/en/innodb-improved-purge-scheduling.html
|
||||
[10]:http://bugs.mysql.com/bug.php?id=1341
|
||||
[11]:https://www.percona.com/software/percona-monitoring-plugins
|
||||
@ -1,3 +1,4 @@
|
||||
[translating by KevinSJ]
|
||||
Linux_Logo – A Command Line Tool to Print Color ANSI Logos of Linux Distributions
|
||||
================================================================================
|
||||
linuxlogo or linux_logo is a Linux command line utility that generates a color ANSI picture of Distribution logo with a few system information.
|
||||
@ -180,4 +181,4 @@ via: http://www.tecmint.com/linux_logo-tool-to-print-color-ansi-logos-of-linux/
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://www.tecmint.com/author/avishek/
|
||||
[1]:http://www.tecmint.com/screenfetch-system-information-generator-for-linux/
|
||||
[1]:http://www.tecmint.com/screenfetch-system-information-generator-for-linux/
|
||||
@ -1,239 +0,0 @@
|
||||
在RHEL/CentOS 7.0中安装LAMP（Linux、 Apache、 MariaDB、 PHP/PhpMyAdmin）
|
||||
================================================================================
|
||||
跳过LAMP的介绍因为我认为你们大多数已经知道了。这个教程会集中在如何在升级到Apache 2.4的 Red Hat Enterprise Linux 7.0 和 CentOS 7.0中安装和配置LAMP-Linux Apache、 MariaDB、 PHP、PhpMyAdmin。
|
||||
|
||||
|
||||
|
||||
在RHEL/CentOS 7.0中安装LAMP
|
||||
|
||||
#### 要求 ####
|
||||
|
||||
根据使用的发行版，RHEL 或者 CentOS 7.0使用下面的链接来执行最小的系统安装，网络使用静态ip
|
||||
|
||||
**对于RHEL 7.0**
|
||||
|
||||
- [RHEL 7.0安装过程][1]
|
||||
- [在RHEL 7.0中注册和启用订阅仓库][2]
|
||||
|
||||
**对于 CentOS 7.0**
|
||||
|
||||
- [CentOS 7.0 安装过程][3]
|
||||
|
||||
### 第一步: 使用基本配置安装apache ###
|
||||
|
||||
**1. 在执行最小系统安装并配置[在RHEL/CentOS 7.0中配置静态ip][4]**就可以从使用下面的命令从官方仓库安装最新的Apache 2.4 httpd服务。
|
||||
|
||||
# yum install httpd
|
||||
|
||||
|
||||
|
||||
安装apache服务
|
||||
|
||||
**2. 安装安城后，使用下面的命令来管理apache守护进程，因为RHEL and CentOS 7.0都将init脚本从SysV升级到了systemd - 你也可以同事使用SysV和Apache脚本来管理服务。**
|
||||
|
||||
# systemctl status|start|stop|restart|reload httpd
|
||||
|
||||
或者
|
||||
|
||||
# service httpd status|start|stop|restart|reload
|
||||
|
||||
或者
|
||||
|
||||
# apachectl configtest| graceful
|
||||
|
||||
|
||||
|
||||
启动apache服务
|
||||
|
||||
**3. 下一步使用systemd初始化脚本来启动apache服务并用firewall-cmd打开RHEL/CentOS 7.0防火墙规则， 这是通过firewalld守护进程管理iptables的默认命令。**
|
||||
|
||||
# firewall-cmd --add-service=http
|
||||
|
||||
**注意**：上面的命令会在系统重启或者firewalld服务重启后失效，因为它是即时的规则，它不会永久生效。要使iptables规则在fiewwall中持久化，使用-permanent选项并重启firewalld服务来生效。
|
||||
|
||||
# firewall-cmd --permanent --add-service=http
|
||||
# systemctl restart firewalld
|
||||
|
||||
|
||||
|
||||
在CentOS 7中启用Firewall
|
||||
|
||||
下面是firewalld其他的重要选项：
|
||||
|
||||
# firewall-cmd --state
|
||||
# firewall-cmd --list-all
|
||||
# firewall-cmd --list-interfaces
|
||||
# firewall-cmd --get-service
|
||||
# firewall-cmd --query-service service_name
|
||||
# firewall-cmd --add-port=8080/tcp
|
||||
|
||||
**4. 要验证apache的功能，打开一个远程浏览器并使用http协议输入你服务器的ip地址(http://server_IP), 应该会显示下图中的默认页面。**
|
||||
|
||||
|
||||
|
||||
Apache默认页
|
||||
|
||||
**5. 现在apache的根地址在/var/www/html，该目录中没有提供任何index文件。如果你想要看见根目录下的文件夹列表，打开apache欢迎配置文件并设置 <LocationMach>下Indexes前的状态从-到+，下面的截图就是一个例子。**
|
||||
|
||||
# nano /etc/httpd/conf.d/welcome.conf
|
||||
|
||||
|
||||
|
||||
Apache目录列出
|
||||
|
||||
**6. 关闭文件，重启apache服务来使设置生效，重载页面来看最终效果。**
|
||||
|
||||
# systemctl restart httpd
|
||||
|
||||
|
||||
|
||||
Apache Index 文件
|
||||
|
||||
### 第二步: 为Apache安装php5支持 ###
|
||||
|
||||
|
||||
**7. 在为apache安装php支持之前，使用下面的命令的得到所有可用的php模块和扩展。**
|
||||
|
||||
# yum search php
|
||||
|
||||
|
||||
|
||||
在
|
||||
|
||||
**8. Depending on what type of applications you want to use, install the required PHP modules from the above list, but for a basic MariaDB support in PHP and PhpMyAdmin you need to install the following modules.**
|
||||
|
||||
# yum install php php-mysql php-pdo php-gd php-mbstring
|
||||
|
||||
|
||||
|
||||
Install PHP Modules
|
||||
|
||||
|
||||
|
||||
Install PHP mbstring Module
|
||||
|
||||
**9. To get a full information list on PHP from your browser, create a info.php file on Apache Document Root using the following command from root account, restart httpd service and direct your browser to the http://server_IP/info.php address.**
|
||||
|
||||
# echo "<?php phpinfo(); ?>" > /var/www/html/info.php
|
||||
# systemctl restart httpd
|
||||
|
||||
|
||||
|
||||
Check PHP Info in CentOS 7
|
||||
|
||||
**10. If you get an error on PHP Date and Timezone, open php.ini configuration file, search and uncomment date.timezone statement, append your physical location and restart Apache daemon.**
|
||||
|
||||
# nano /etc/php.ini
|
||||
|
||||
Locate and change date.timezone line to look like this, using [PHP Supported Timezones list][5].
|
||||
|
||||
date.timezone = Continent/City
|
||||
|
||||
|
||||
|
||||
Set Timezone in PHP
|
||||
|
||||
### Step 3: Install and Configure MariaDB Database ###
|
||||
|
||||
**11. Red Hat Enterprise Linux/CentOS 7.0 switched from MySQL to MariaDB for its default database management system. To install MariaDB database use the following command.**
|
||||
|
||||
# yum install mariadb-server mariadb
|
||||
|
||||
|
||||
|
||||
在CentOS 7中安装PHP
|
||||
|
||||
***12. 安装MariaDB后，开启数据库守护进程并使用mysql_secure_installation脚本来保护数据库（设置root密码、禁止远程root登录、移除测试数据库、移除匿名用户）**
|
||||
|
||||
# systemctl start mariadb
|
||||
# mysql_secure_installation
|
||||
|
||||
|
||||
|
||||
启动MariaDB数据库
|
||||
|
||||
|
||||
|
||||
MySQL安全设置
|
||||
|
||||
**13. 要测试数据库功能，使用root账户登录MariaDB并用quit退出。**
|
||||
|
||||
mysql -u root -p
|
||||
MariaDB > SHOW VARIABLES;
|
||||
MariaDB > quit
|
||||
|
||||
|
||||
|
||||
连接MySQL数据库
|
||||
|
||||
### 第四步: 安装PhpMyAdmin ###
|
||||
|
||||
**14. RHEL 7.0 或者 CentOS 7.0仓库默认没有提供PhpMyAdmin二进制安装包。如果你不适应使用MySQL命令行来管理你的数据库，你可以通过下面的命令启用CentOS 7.0 rpmforge仓库来安装PhpMyAdmin。**
|
||||
|
||||
# yum install http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.3-1.el7.rf.x86_64.rpm
|
||||
|
||||
启用rpmforge仓库后，下面安装PhpMyAdmin。
|
||||
|
||||
# yum install phpmyadmin
|
||||
|
||||
|
||||
|
||||
启用RPMForge仓库
|
||||
|
||||
**15. 下面配置PhpMyAdmin的phpmyadmin.conf来允许远程连接，它位于Apache conf.d目录下，并注释掉下面的行。**
|
||||
|
||||
# nano /etc/httpd/conf.d/phpmyadmin.conf
|
||||
|
||||
使用#来注释掉行。
|
||||
|
||||
# Order Deny,Allow
|
||||
# Deny from all
|
||||
# Allow from 127.0.0.1
|
||||
|
||||
|
||||
|
||||
允许远程PhpMyAdmin访问
|
||||
|
||||
**16. 要使用cookie验证来登录PhpMyAdmin，像下面的截图那样使用[生成字符串][6]添加一个blowfish字符串到config.inc.php文件下，重启apache服务并打开URL：http://server_IP/phpmyadmin/。**
|
||||
|
||||
# nano /etc/httpd/conf.d/phpmyadmin.conf
|
||||
# systemctl restart httpd
|
||||
|
||||
|
||||
|
||||
在PhpMyAdmin中添加Blowfish
|
||||
|
||||
|
||||
|
||||
PhpMyAdmin面板
|
||||
|
||||
### 第五步: 系统范围启用LAMP ###
|
||||
|
||||
**17. 如果你需要在重启后自动运行MariaDB和Apache服务，你需要系统级地启用它们。**
|
||||
|
||||
# systemctl enable mariadb
|
||||
# systemctl enable httpd
|
||||
|
||||
|
||||
|
||||
系统级启用服务
|
||||
|
||||
这就是在Red Hat Enterprise 7.0或者CentOS 7.0中安装LAMP的过程。CentOS/RHEL 7.0上关于LAMP洗系列文章将会讨论在Apache中创建虚拟主机，生成SSL证书、密钥和添加SSL事物支持。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: http://www.tecmint.com/install-lamp-in-centos-7/
|
||||
|
||||
作者：[Matei Cezar][a]
|
||||
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) 原创翻译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:http://www.tecmint.com/author/cezarmatei/
|
||||
[1]:http://www.tecmint.com/redhat-enterprise-linux-7-installation/
|
||||
[2]:http://www.tecmint.com/enable-redhat-subscription-reposiories-and-updates-for-rhel-7/
|
||||
[3]:http://www.tecmint.com/centos-7-installation/
|
||||
[4]:http://www.tecmint.com/configure-network-interface-in-rhel-centos-7-0/
|
||||
[5]:http://php.net/manual/en/timezones.php
|
||||
[6]:http://www.question-defense.com/tools/phpmyadmin-blowfish-secret-generator
|
||||
Loading…
Reference in New Issue
Block a user