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sources/talk/20181116 Akash Angle- How do you Fedora.md
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sources/talk/20181116 Akash Angle- How do you Fedora.md
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@ -0,0 +1,61 @@
|
||||
Akash Angle: How do you Fedora?
|
||||
======
|
||||
|
||||
|
||||
We recently interviewed Akash Angle on how he uses Fedora. This is [part of a series][1] on the Fedora Magazine. The series profiles Fedora users and how they use Fedora to get things done. Contact us on the [feedback form][2] to express your interest in becoming a interviewee.
|
||||
|
||||
### Who is Akash Angle?
|
||||
|
||||
Akash is a Linux user who ditched Windows some time ago. An avid Fedora user for the past 9 years, he has tried out almost all the Fedora flavors and spins to get his day to day tasks done. He was introduced to Fedora by a school friend.
|
||||
|
||||
### What Hardware?
|
||||
|
||||
Akash uses a Lenovo B490 at work. It is equipped with an Intel Core i3-3310 Processor, and a 240GB Kingston SSD. “This laptop is great for day to work like surfing the internet, blogging, and a little bit of photo editing and video editing too. Although not a professional laptop and the specs not being that high end, it does the job perfectly,” says Akash.
|
||||
|
||||
He uses a Logitech basic wireless mouse and would like to eventually get a mechanical keyboard. His personal computer — which is a custom-built desktop — has the latest 7th-generation Intel i5 7400 processor, and 8GB Corsair Vengeance RAM.
|
||||
|
||||
![][3]
|
||||
|
||||
### What Software?
|
||||
|
||||
Akash is a fan of the GNOME 3 desktop environment. He loves most of the goodies and bells and whistles the OS can throw in for getting basic tasks done.
|
||||
|
||||
For practical reasons he prefers a fresh installation as a way of upgrading to the latest Fedora version. He thinks Fedora 29 is arguably the the best workstation out there. Akash says this has been backed up by reviews of various tech evangelists and open source news sites.
|
||||
|
||||
To play videos, his go-to is the VLC video player packaged as a [Flatpak][4], which gives him the latest stable version. When Akash wants to make screenshots, the ultimate tool for him is [Shutter, which the Magazine has covered in the past][5]. For graphics, GIMP is something without which he wouldn’t be able to work.
|
||||
|
||||
Google Chrome stable, and the dev channel, are his most used web browsers. He also uses Chromium and the default version of Firefox, and sometimes even Opera makes its way into the party as well.
|
||||
|
||||
All the rest of the magic Akash does is from the terminal, as he is a power user. The GNOME Terminal app is the one for him.
|
||||
|
||||
#### Favorite wallpapers
|
||||
|
||||
One of his favorite wallpapers originally coming from Fedora 16 is the following one:
|
||||
|
||||
![][6]
|
||||
|
||||
And this is the one he currently uses on his Fedora 29 Workstation today:
|
||||
|
||||
![][7]
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://fedoramagazine.org/akash-angle-how-do-you-fedora/
|
||||
|
||||
作者：[Adam Šamalík][a]
|
||||
选题：[lujun9972][b]
|
||||
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/author/asamalik/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://fedoramagazine.org/tag/how-do-you-fedora/
|
||||
[2]: https://fedoramagazine.org/submit-an-idea-or-tip/
|
||||
[3]: https://fedoramagazine.org/wp-content/uploads/2018/11/akash-angle-desktop-300x259.png
|
||||
[4]: https://fedoramagazine.org/getting-started-flatpak/
|
||||
[5]: https://fedoramagazine.org/screenshot-everything-shutter-fedora/
|
||||
[6]: https://fedoramagazine.org/wp-content/uploads/2018/11/Fedora-16-300x188.png
|
||||
[7]: https://fedoramagazine.org/wp-content/uploads/2018/11/wallpaper2you_72588-300x169.jpg
|
||||
@ -1,3 +1,4 @@
|
||||
（translating by runningwater)
|
||||
Version Control Before Git with CVS
|
||||
======
|
||||
Github was launched in 2008. If your software engineering career, like mine, is no older than Github, then Git may be the only version control software you have ever used. While people sometimes grouse about its steep learning curve or unintuitive interface, Git has become everyone’s go-to for version control. In Stack Overflow’s 2015 developer survey, 69.3% of respondents used Git, almost twice as many as used the second-most-popular version control system, Subversion. After 2015, Stack Overflow stopped asking developers about the version control systems they use, perhaps because Git had become so popular that the question was uninteresting.
|
||||
@ -296,7 +297,7 @@ via: https://twobithistory.org/2018/07/07/cvs.html
|
||||
|
||||
作者：[Two-Bit History][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
译者：[runningwater](https://github.com/runningwater)
|
||||
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
|
||||
|
||||
@ -1,3 +1,5 @@
|
||||
translating---geekpi
|
||||
|
||||
Anbox: How To Install Google Play Store And Enable ARM (libhoudini) Support, The Easy Way
|
||||
======
|
||||
**[Anbox][1], or Android in a Box, is a free and open source tool that allows running Android applications on Linux.** It works by running the Android runtime environment in an LXC container, recreating the directory structure of Android as a mountable loop image, while using the native Linux kernel to execute applications.
|
||||
|
||||
@ -1,83 +0,0 @@
|
||||
[translating by ChiZelin]
|
||||
Monitoring database health and behavior: Which metrics matter?
|
||||
======
|
||||
Monitoring your database can be overwhelming or seem not important. Here's how to do it right.
|
||||
|
||||
|
||||
We don’t talk about our databases enough. In this age of instrumentation, we monitor our applications, our infrastructure, and even our users, but we sometimes forget that our database deserves monitoring, too. That’s largely because most databases do their job so well that we simply trust them to do it. Trust is great, but confirmation of our assumptions is even better.
|
||||
|
||||
|
||||
|
||||
### Why monitor your databases?
|
||||
|
||||
There are plenty of reasons to monitor your databases, most of which are the same reasons you'd monitor any other part of your systems: Knowing what’s going on in the various components of your applications makes you a better-informed developer who makes smarter decisions.
|
||||
|
||||
|
||||
|
||||
More specifically, databases are great indicators of system health and behavior. Odd behavior in the database can point to problem areas in your applications. Alternately, when there’s odd behavior in your application, you can use database metrics to help expedite the debugging process.
|
||||
|
||||
### The problem
|
||||
|
||||
The slightest investigation reveals one problem with monitoring databases: Databases have a lot of metrics. "A lot" is an understatement—if you were Scrooge McDuck, you could swim through all of the metrics available. If this were Wrestlemania, the metrics would be folding chairs. Monitoring them all doesn’t seem practical, so how do you decide which metrics to monitor?
|
||||
|
||||
|
||||
|
||||
### The solution
|
||||
|
||||
The best way to start monitoring databases is to identify some foundational, database-agnostic metrics. These metrics create a great start to understanding the lives of your databases.
|
||||
|
||||
### Throughput: How much is the database doing?
|
||||
|
||||
The easiest way to start monitoring a database is to track the number of requests the database receives. We have high expectations for our databases; we expect them to store data reliably and handle all of the queries we throw at them, which could be one massive query a day or millions of queries from users all day long. Throughput can tell you which of those is true.
|
||||
|
||||
You can also group requests by type (reads, writes, server-side, client-side, etc.) to begin analyzing the traffic.
|
||||
|
||||
### Execution time: How long does it take the database to do its job?
|
||||
|
||||
This metric seems obvious, but it often gets overlooked. You don’t just want to know how many requests the database received, but also how long the database spent on each request. It’s important to approach execution time with context, though: What's slow for a time-series database like InfluxDB isn’t the same as what's slow for a relational database like MySQL. Slow in InfluxDB might mean milliseconds, whereas MySQL’s default value for its `SLOW_QUERY` variable is ten seconds.
|
||||
|
||||
|
||||
|
||||
Monitoring execution time is not the same thing as improving execution time, so beware of the temptation to spend time on optimizations if you have other problems in your app to fix.
|
||||
|
||||
### Concurrency: How many jobs is the database doing at the same time?
|
||||
|
||||
Once you know how many requests the database is handling and how long each one takes, you need to add a layer of complexity to start getting real value from these metrics.
|
||||
|
||||
If the database receives ten requests and each one takes ten seconds to complete, is the database busy for 100 seconds, ten seconds—or somewhere in between? The number of concurrent tasks changes the way the database’s resources are used. When you consider things like the number of connections and threads, you’ll start to get a fuller picture of your database metrics.
|
||||
|
||||
Concurrency can also affect latency, which includes not only the time it takes for the task to be completed (execution time) but also the time the task needs to wait before it’s handled.
|
||||
|
||||
### Utilization: What percentage of the time was the database busy?
|
||||
|
||||
Utilization is a culmination of throughput, execution time, and concurrency to determine how often the database was available—or alternatively, how often the database was too busy to respond to a request.
|
||||
|
||||
|
||||
|
||||
This metric is particularly useful for determining the overall health and performance of your database. If it’s available to respond to requests only 80% of the time, you can reallocate resources, work on optimization, or otherwise make changes to get closer to high availability.
|
||||
|
||||
### The good news
|
||||
|
||||
It can seem overwhelming to monitor and analyze, especially because most of us aren’t database experts and we may not have time to devote to understanding these metrics. But the good news is that most of this work is already done for us. Many databases have an internal performance database (Postgres: pg_stats, CouchDB: Runtime_Statistics, InfluxDB: _internal, etc.), which is designed by database engineers to monitor the metrics that matter for that particular database. You can see things as broad as the number of slow queries or as detailed as the average microseconds each event in the database takes.
|
||||
|
||||
### Conclusion
|
||||
|
||||
Databases create enough metrics to keep us all busy for a long time, and while the internal performance databases are full of useful information, it’s not always clear which metrics you should care about. Start with throughput, execution time, concurrency, and utilization, which provide enough information for you to start understanding the patterns in your database.
|
||||
|
||||
|
||||
|
||||
Are you monitoring your databases? Which metrics have you found to be useful? Tell me about it!
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/10/database-metrics-matter
|
||||
|
||||
作者：[Katy Farmer][a]
|
||||
选题：[lujun9972][b]
|
||||
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/thekatertot
|
||||
[b]: https://github.com/lujun9972
|
||||
@ -0,0 +1,157 @@
|
||||
5 Easy Tips for Linux Web Browser Security
|
||||
======
|
||||
|
||||
|
||||
If you use your Linux desktop and never open a web browser, you are a special kind of user. For most of us, however, a web browser has become one of the most-used digital tools on the planet. We work, we play, we get news, we interact, we bank… the number of things we do via a web browser far exceeds what we do in local applications. Because of that, we need to be cognizant of how we work with web browsers, and do so with a nod to security. Why? Because there will always be nefarious sites and people, attempting to steal information. Considering the sensitive nature of the information we send through our web browsers, it should be obvious why security is of utmost importance.
|
||||
|
||||
So, what is a user to do? In this article, I’ll offer a few basic tips, for users of all sorts, to help decrease the chances that your data will end up in the hands of the wrong people. I will be demonstrating on the Firefox web browser, but many of these tips cross the application threshold and can be applied to any flavor of web browser.
|
||||
|
||||
### 1. Choose Your Browser Wisely
|
||||
|
||||
Although most of these tips apply to most browsers, it is imperative that you select your web browser wisely. One of the more important aspects of browser security is the frequency of updates. New issues are discovered quite frequently and you need to have a web browser that is as up to date as possible. Of major browsers, here is how they rank with updates released in 2017:
|
||||
|
||||
1. Chrome released 8 updates (with Chromium following up with numerous security patches throughout the year).
|
||||
|
||||
2. Firefox released 7 updates.
|
||||
|
||||
3. Edge released 2 updates.
|
||||
|
||||
4. Safari released 1 update (although Apple does release 5-6 security patches yearly).
|
||||
|
||||
|
||||
|
||||
|
||||
But even if your browser of choice releases an update every month, if you (as a user) don’t upgrade, that update does you no good. This can be problematic with certain Linux distributions. Although many of the more popular flavors of Linux do a good job of keeping web browsers up to date, others do not. So, it’s crucial that you manually keep on top of browser updates. This might mean your distribution of choice doesn’t include the latest version of your web browser of choice in its standard repository. If that’s the case, you can always manually download the latest version of the browser from the developer’s download page and install from there.
|
||||
|
||||
If you like to live on the edge, you can always use a beta or daily build version of your browser. Do note, that using a daily build or beta version does come with it the possibility of unstable software. Say, however, you’re okay with using a daily build of Firefox on a Ubuntu-based distribution. To do that, add the necessary repository with the command:
|
||||
|
||||
```
|
||||
sudo apt-add-repository ppa:ubuntu-mozilla-daily/ppa
|
||||
```
|
||||
|
||||
Update apt and install the daily Firefox with the commands:
|
||||
|
||||
```
|
||||
sudo apt-get update
|
||||
sudo apt-get install firefox
|
||||
```
|
||||
|
||||
What’s most important here is to never allow your browser to get far out of date. You want to have the most updated version possible on your desktop. Period. If you fail this one thing, you could be using a browser that is vulnerable to numerous issues.
|
||||
|
||||
### 2. Use A Private Window
|
||||
|
||||
Now that you have your browser updated, how do you best make use of it? If you happen to be of the really concerned type, you should consider always using a private window. Why? Private browser windows don’t retain your data: No passwords, no cookies, no cache, no history… nothing. The one caveat to browsing through a private window is that (as you probably expect), every time you go back to a web site, or use a service, you’ll have to re-type any credentials to log in. If you’re serious about browser security, never saving credentials should be your default behavior.
|
||||
|
||||
This leads me to a reminder that everyone needs: Make your passwords strong! In fact, at this point in the game, everyone should be using a password manager to store very strong passwords. My password manager of choice is [Universal Password Manager][1].
|
||||
|
||||
### 3\. Protect Your Passwords
|
||||
|
||||
For some, having to retype those passwords every single time might be too much. So what do you do if you want to protect those passwords, while not having to type them constantly? If you use Firefox, there’s a built-in tool, called Master Password. With this enabled, none of your browser’s saved passwords are accessible, until you correctly type the master password. To set this up, do the following:
|
||||
|
||||
1. Open Firefox.
|
||||
|
||||
2. Click the menu button.
|
||||
|
||||
3. Click Preferences.
|
||||
|
||||
4. In the Preferences window, click Privacy & Security.
|
||||
|
||||
5. In the resulting window, click the checkbox for Use a master password (Figure 1).
|
||||
|
||||
6. When prompted, type and verify your new master password (Figure 2).
|
||||
|
||||
7. Close and reopen Firefox.
|
||||
|
||||
|
||||
|
||||
|
||||
![Master Password][3]
|
||||
|
||||
Figure 1: The Master Password option in Firefox Preferences.
|
||||
|
||||
[Used with permission][4]
|
||||
|
||||
![Setting password][6]
|
||||
|
||||
Figure 2: Setting the Master Password in Firefox.
|
||||
|
||||
[Used with permission][4]
|
||||
|
||||
### 4\. Know your Extensions
|
||||
|
||||
There are plenty of privacy-focused extensions available for most browsers. What extensions you use will depend upon what you want to focus on. For myself, I choose the following extensions for Firefox:
|
||||
|
||||
* [Firefox Multi-Account Containers][7] \- Allows you to configure certain sites to open in a containerized tab.
|
||||
|
||||
* [Facebook Container][8] \- Always opens Facebook in a containerized tab (Firefox Multi-Account Containers is required for this).
|
||||
|
||||
* [Avast Online Security][9] \- Identifies and blocks known phishing sites and displays a website’s security rating (curated by the Avast community of over 400 million users).
|
||||
|
||||
* [Mining Blocker][10] \- Blocks all CPU-Crypto Miners before they are loaded.
|
||||
|
||||
* [PassFF][11] \- Integrates with pass (A UNIX password manager) to store credentials safely.
|
||||
|
||||
* [Privacy Badger][12] \- Automatically learns to block trackers.
|
||||
|
||||
* [uBlock Origin][13] \- Blocks trackers based on known lists.
|
||||
|
||||
|
||||
Of course, you’ll find plenty more security-focused extensions for:
|
||||
|
||||
|
||||
|
||||
+ [Firefox][2]
|
||||
|
||||
+ [Chrome, Chromium, & Vivaldi][5]
|
||||
|
||||
+ [Opera][14]
|
||||
|
||||
|
||||
Not every web browser offers extensions. Some, such as Midoria, offer a limited about of built-in plugins, that can be enabled/disabled (Figure 3). However, you won’t find third-party plugins available for the majority of these lightweight browsers.
|
||||
|
||||
![Midori Browser][15]
|
||||
|
||||
Figure 3: The Midori Browser plugins window.
|
||||
|
||||
[Used with permission][4]
|
||||
|
||||
### 5\. Virtualize
|
||||
|
||||
For those that are concerned about releasing locally stored data to prying eyes, one option would be to only use a browser on a virtual machine. To do this, install the likes of [VirtualBox][16], install a Linux guest, and then run whatever browser you like in the virtual environment. If you then apply the above tips, you can be sure your browsing experience will be safe.
|
||||
|
||||
### The Truth of the Matter
|
||||
|
||||
The truth is, if the machine you are working from is on a network, you’re never going to be 100% safe. However, if you use that web browser intelligently you’ll get more bang out of your security buck and be less prone to having data stolen. The silver lining with Linux is that the chances of getting malicious software installed on your machine is exponentially less than if you were using another platform. Just remember to always use the latest release of your browser, keep your operating system updated, and use caution with the sites you visit.
|
||||
|
||||
Learn more about Linux through the free ["Introduction to Linux" ][17] course from The Linux Foundation and edX.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.linux.com/learn/intro-to-linux/2018/11/5-easy-tips-linux-web-browser-security
|
||||
|
||||
作者：[Jack Wallen][a]
|
||||
选题：[lujun9972][b]
|
||||
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
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: http://upm.sourceforge.net/
|
||||
[2]: https://addons.mozilla.org/en-US/firefox/search/?q=security
|
||||
[3]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/browsersecurity_1.jpg?itok=gHMPKEvr (Master Password)
|
||||
[4]: https://www.linux.com/licenses/category/used-permission
|
||||
[5]: https://chrome.google.com/webstore/search/security
|
||||
[6]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/browsersecurity_2.jpg?itok=4L7DR2Ik (Setting password)
|
||||
[7]: https://addons.mozilla.org/en-US/firefox/addon/multi-account-containers/?src=search
|
||||
[8]: https://addons.mozilla.org/en-US/firefox/addon/facebook-container/?src=search
|
||||
[9]: https://addons.mozilla.org/en-US/firefox/addon/avast-online-security/?src=search
|
||||
[10]: https://addons.mozilla.org/en-US/firefox/addon/miningblocker/?src=search
|
||||
[11]: https://addons.mozilla.org/en-US/firefox/addon/passff/?src=search
|
||||
[12]: https://addons.mozilla.org/en-US/firefox/addon/privacy-badger17/
|
||||
[13]: https://addons.mozilla.org/en-US/firefox/addon/ublock-origin/?src=search
|
||||
[14]: https://addons.opera.com/en/search/?query=security
|
||||
[15]: https://www.linux.com/sites/lcom/files/styles/rendered_file/public/browsersecurity_3.jpg?itok=hdNor0gw (Midori Browser)
|
||||
[16]: https://www.virtualbox.org/
|
||||
[17]: https://training.linuxfoundation.org/linux-courses/system-administration-training/introduction-to-linux
|
||||
@ -1,218 +0,0 @@
|
||||
Translating by Jamkr
|
||||
|
||||
How to partition and format a drive on Linux
|
||||
======
|
||||
Everything you wanted to know about setting up storage but were afraid to ask.
|
||||
|
||||
|
||||
On most computer systems, Linux or otherwise, when you plug a USB thumb drive in, you're alerted that the drive exists. If the drive is already partitioned and formatted to your liking, you just need your computer to list the drive somewhere in your file manager window or on your desktop. It's a simple requirement and one that the computer generally fulfills.
|
||||
|
||||
Sometimes, however, a drive isn't set up the way you want. For those times, you need to know how to find and prepare a storage device connected to your machine.
|
||||
|
||||
### What are block devices?
|
||||
|
||||
A hard drive is generically referred to as a "block device" because hard drives read and write data in fixed-size blocks. This differentiates a hard drive from anything else you might plug into your computer, like a printer, gamepad, microphone, or camera. The easy way to list the block devices attached to your Linux system is to use the **lsblk** (list block devices) command:
|
||||
|
||||
```
|
||||
$ lsblk
|
||||
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
|
||||
sda 8:0 0 238.5G 0 disk
|
||||
├─sda1 8:1 0 1G 0 part /boot
|
||||
└─sda2 8:2 0 237.5G 0 part
|
||||
└─luks-e2bb...e9f8 253:0 0 237.5G 0 crypt
|
||||
├─fedora-root 253:1 0 50G 0 lvm /
|
||||
├─fedora-swap 253:2 0 5.8G 0 lvm [SWAP]
|
||||
└─fedora-home 253:3 0 181.7G 0 lvm /home
|
||||
sdb 8:16 1 14.6G 0 disk
|
||||
└─sdb1 8:17 1 14.6G 0 part
|
||||
```
|
||||
|
||||
The device identifiers are listed in the left column, each beginning with **sd** , and ending with a letter, starting with **a**. Each partition of each drive is assigned a number, starting with **1**. For example, the second partition of the first drive is **sda2**. If you're not sure what a partition is, that's OK—just keep reading.
|
||||
|
||||
The **lsblk** command is nondestructive and used only for probing, so you can run it without any fear of ruining data on a drive.
|
||||
|
||||
### Testing with dmesg
|
||||
|
||||
If in doubt, you can test device label assignments by looking at the tail end of the **dmesg** command, which displays recent system log entries including kernel events (such as attaching and detaching a drive). For instance, if you want to make sure a thumb drive is really **/dev/sdc** , plug the drive into your computer and run this **dmesg** command:
|
||||
|
||||
```
|
||||
$ sudo dmesg | tail
|
||||
```
|
||||
|
||||
The most recent drive listed is the one you just plugged in. If you unplug it and run that command again, you'll see the device has been removed. If you plug it in again and run the command, the device will be there. In other words, you can monitor the kernel's awareness of your drive.
|
||||
|
||||
### Understanding filesystems
|
||||
|
||||
If all you need is the device label, your work is done. But if your goal is to create a usable drive, you must give the drive a filesystem.
|
||||
|
||||
If you're not sure what a filesystem is, it's probably easier to understand the concept by learning what happens when you have no filesystem at all. If you have a spare drive that has no important data on it whatsoever, you can follow along with this example. Otherwise, do not attempt this exercise, because it will DEFINITELY ERASE DATA, by design.
|
||||
|
||||
It is possible to utilize a drive without a filesystem. Once you have definitely, correctly identified a drive, and you have absolutely verified there is nothing important on it, plug it into your computer—but do not mount it. If it auto-mounts, then unmount it manually.
|
||||
|
||||
```
|
||||
$ su -
|
||||
# umount /dev/sdx{,1}
|
||||
```
|
||||
|
||||
To safeguard against disastrous copy-paste errors, these examples use the unlikely **sdx** label for the drive.
|
||||
|
||||
Now that the drive is unmounted, try this:
|
||||
|
||||
```
|
||||
# echo 'hello world' > /dev/sdx
|
||||
```
|
||||
|
||||
You have just written data to the block device without it being mounted on your system or having a filesystem.
|
||||
|
||||
To retrieve the data you just wrote, you can view the raw data on the drive:
|
||||
|
||||
```
|
||||
# head -n 1 /dev/sdx
|
||||
hello world
|
||||
```
|
||||
|
||||
That seemed to work pretty well, but imagine that the phrase "hello world" is one file. If you want to write a new "file" using this method, you must:
|
||||
|
||||
1. Know there's already an existing "file" on line 1
|
||||
2. Know that the existing "file" takes up only 1 line
|
||||
3. Derive a way to append new data, or else rewrite line 1 while writing line 2
|
||||
|
||||
|
||||
|
||||
For example:
|
||||
|
||||
```
|
||||
# echo 'hello world
|
||||
> this is a second file' >> /dev/sdx
|
||||
```
|
||||
|
||||
To get the first file, nothing changes.
|
||||
|
||||
```
|
||||
# head -n 1 /dev/sdx
|
||||
hello world
|
||||
```
|
||||
|
||||
But it's more complex to get the second file.
|
||||
|
||||
```
|
||||
# head -n 2 /dev/sdx | tail -n 1
|
||||
this is a second file
|
||||
```
|
||||
|
||||
Obviously, this method of writing and reading data is not practical, so developers have created systems to keep track of what constitutes a file, where one file begins and ends, and so on.
|
||||
|
||||
Most filesystems require a partition.
|
||||
|
||||
### Creating partitions
|
||||
|
||||
A partition on a hard drive is a sort of boundary on the device telling each filesystem what space it can occupy. For instance, if you have a 4GB thumb drive, you can have a partition on that device taking up the entire drive (4GB), two partitions that each take 2GB (or 1 and 3, if you prefer), three of some variation of sizes, and so on. The combinations are nearly endless.
|
||||
|
||||
Assuming your drive is 4GB, you can create one big partition from a terminal with the GNU **parted** command:
|
||||
|
||||
```
|
||||
# parted /dev/sdx --align opt mklabel msdos 0 4G
|
||||
```
|
||||
|
||||
This command specifies the device path first, as required by **parted**.
|
||||
|
||||
The **\--align** option lets **parted** find the partition's optimal starting and stopping point.
|
||||
|
||||
The **mklabel** command creates a partition table (called a disk label) on the device. This example uses the **msdos** label because it's a very compatible and popular label, although **gpt** is becoming more common.
|
||||
|
||||
The desired start and end points of the partition are defined last. Since the **\--align opt** flag is used, **parted** will adjust the size as needed to optimize drive performance, but these numbers serve as a guideline.
|
||||
|
||||
Next, create the actual partition. If your start and end choices are not optimal, **parted** warns you and asks if you want to make adjustments.
|
||||
|
||||
```
|
||||
# parted /dev/sdx -a opt mkpart primary 0 4G
|
||||
|
||||
Warning: The resulting partition is not properly aligned for best performance: 1s % 2048s != 0s
|
||||
Ignore/Cancel? C
|
||||
# parted /dev/sdx -a opt mkpart primary 2048s 4G
|
||||
```
|
||||
|
||||
If you run **lsblk** again (you may have to unplug the drive and plug it back in), you'll see that your drive now has one partition on it.
|
||||
|
||||
### Manually creating a filesystem
|
||||
|
||||
There are many filesystems available. Some are free and open source, while others are not. Some companies decline to support open source filesystems, so their users can't read from open filesystems, while open source users can't read from closed ones without reverse-engineering them.
|
||||
|
||||
This disconnect notwithstanding, there are lots of filesystems you can use, and the one you choose depends on the drive's purpose. If you want a drive to be compatible across many systems, then your only choice right now is the exFAT filesystem. Microsoft has not submitted exFAT code to any open source kernel, so you may have to install exFAT support with your package manager, but support for exFAT is included in both Windows and MacOS.
|
||||
|
||||
Once you have exFAT support installed, you can create an exFAT filesystem on your drive in the partition you created.
|
||||
|
||||
```
|
||||
# mkfs.exfat -n myExFatDrive /dev/sdx1
|
||||
```
|
||||
|
||||
Now your drive is readable and writable by closed systems and by open source systems utilizing additional (and as-yet unsanctioned by Microsoft) kernel modules.
|
||||
|
||||
A common filesystem native to Linux is [ext4][1]. It's arguably a troublesome filesystem for portable drives since it retains user permissions, which are often different from one computer to another, but it's generally a reliable and flexible filesystem. As long as you're comfortable managing permissions, ext4 is a great, journaled filesystem for portable drives.
|
||||
|
||||
```
|
||||
# mkfs.ext4 -L myExt4Drive /dev/sdx1
|
||||
```
|
||||
|
||||
Unplug your drive and plug it back in. For ext4 portable drives, use **sudo** to create a directory and grant permission to that directory to a user and a group common across your systems. If you're not sure what user and group to use, you can either modify read/write permissions with **sudo** or root on the system that's having trouble with the drive.
|
||||
|
||||
### Using desktop tools
|
||||
|
||||
It's great to know how to deal with drives with nothing but a Linux shell standing between you and the block device, but sometimes you just want to get a drive ready to use without so much insightful probing. Excellent tools from both the GNOME and KDE developers can make your drive prep easy.
|
||||
|
||||
[GNOME Disks][2] and [KDE Partition Manager][3] are graphical interfaces providing an all-in-one solution for everything this article has explained so far. Launch either of these applications to see a list of attached devices (in the left column), create or resize partitions, and create a filesystem.
|
||||
|
||||
![KDE Partition Manager][5]
|
||||
|
||||
KDE Partition Manager
|
||||
|
||||
The GNOME version is, predictably, simpler than the KDE version, so I'll demo the more complex one—it's easy to figure out GNOME Disks if that's what you have handy.
|
||||
|
||||
Launch KDE Partition Manager and enter your root password.
|
||||
|
||||
From the left column, select the disk you want to format. If your drive isn't listed, make sure it's plugged in, then select **Tools** > **Refresh devices** (or **F5** on your keyboard).
|
||||
|
||||
Don't continue unless you're ready to destroy the drive's existing partition table. With the drive selected, click **New Partition Table** in the top toolbar. You'll be prompted to select the label you want to give the partition table: either **gpt** or **msdos**. The former is more flexible and can handle larger drives, while the latter is, like many Microsoft technologies, the de-facto standard by force of market share.
|
||||
|
||||
Now that you have a fresh partition table, right-click on your device in the right panel and select **New** to create a new partition. Follow the prompts to set the type and size of your partition. This action combines the partitioning step with creating a filesystem.
|
||||
|
||||
![Create a new partition][7]
|
||||
|
||||
Creating a new partition
|
||||
|
||||
To apply your changes to the drive, click the **Apply** button in the top-left corner of the window.
|
||||
|
||||
### Hard drives, easy drives
|
||||
|
||||
Dealing with hard drives is easy on Linux, and it's even easier if you understand the language of hard drives. Since switching to Linux, I've been better equipped to prepare drives in whatever way I want them to work for me. It's also been easier for me to recover lost data because of the transparency Linux provides when dealing with storage.
|
||||
|
||||
Here are a final few tips, if you want to experiment and learn more about hard drives:
|
||||
|
||||
1. Back up your data, and not just the data on the drive you're experimenting with. All it takes is one wrong move to destroy the partition of an important drive (which is a great way to learn about recreating lost partitions, but not much fun).
|
||||
2. Verify and then re-verify that the drive you are targeting is the correct drive. I frequently use **lsblk** to make sure I haven't moved drives around on myself. (It's easy to remove two drives from two separate USB ports, then mindlessly reattach them in a different order, causing them to get new drive labels.)
|
||||
3. Take the time to "destroy" a test drive and see if you can recover the data. It's a good learning experience to recreate a partition table or try to get data back after a filesystem has been removed.
|
||||
|
||||
|
||||
|
||||
For extra fun, if you have a closed operating system lying around, try getting an open source filesystem working on it. There are a few projects working toward this kind of compatibility, and trying to get them working in a stable and reliable way is a good weekend project.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/11/partition-format-drive-linux
|
||||
|
||||
作者：[Seth Kenlon][a]
|
||||
选题：[lujun9972][b]
|
||||
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
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/article/17/5/introduction-ext4-filesystem
|
||||
[2]: https://wiki.gnome.org/Apps/Disks
|
||||
[3]: https://www.kde.org/applications/system/kdepartitionmanager/
|
||||
[4]: /file/413586
|
||||
[5]: https://opensource.com/sites/default/files/uploads/blockdevices_kdepartition.jpeg (KDE Partition Manager)
|
||||
[6]: /file/413591
|
||||
[7]: https://opensource.com/sites/default/files/uploads/blockdevices_newpartition.jpeg (Create a new partition)
|
||||
@ -1,124 +0,0 @@
|
||||
translating---geekpi
|
||||
|
||||
Automate a web browser with Selenium
|
||||
======
|
||||
|
||||
|
||||
[Selenium][1] is a great tool for browser automation. With Selenium IDE you can record sequences of commands (like click, drag and type), validate the result and finally store this automated test for later. This is great for active development in the browser. But when you want to integrate these tests with your CI/CD flow it’s time to move on to Selenium WebDriver.
|
||||
|
||||
WebDriver exposes an API with bindings for many programming languages, which lets you integrate browser tests with your other tests. This post shows you how to run WebDriver in a container and use it together with a Python program.
|
||||
|
||||
### Running Selenium with Podman
|
||||
|
||||
Podman is the container runtime in the following examples. See [this previous post][2] for how to get started with Podman.
|
||||
|
||||
This example uses a standalone container for Selenium that contains both the WebDriver server and the browser itself. To launch the server container in the background run the following comand:
|
||||
|
||||
```
|
||||
$ podman run -d --network host --privileged --name server \
|
||||
docker.io/selenium/standalone-firefox
|
||||
```
|
||||
|
||||
When you run the container with the privileged flag and host networking, you can connect to this container later from a Python program. You do not need to use sudo.
|
||||
|
||||
### Using Selenium from Python
|
||||
|
||||
Now you can provide a simple program that uses this server. This program is minimal, but should give you an idea about what you can do:
|
||||
|
||||
```
|
||||
from selenium import webdriver
|
||||
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
|
||||
|
||||
server ="http://127.0.0.1:4444/wd/hub"
|
||||
|
||||
driver = webdriver.Remote(command_executor=server,
|
||||
desired_capabilities=DesiredCapabilities.FIREFOX)
|
||||
|
||||
print("Loading page...")
|
||||
driver.get("https://fedoramagazine.org/")
|
||||
print("Loaded")
|
||||
assert "Fedora" in driver.title
|
||||
|
||||
driver.quit()
|
||||
print("Done.")
|
||||
```
|
||||
|
||||
First the program connects to the container you already started. Then it loads the Fedora Magazine web page and asserts that “Fedora” is part of the page title. Finally, it quits the session.
|
||||
|
||||
Python bindings are required in order to run the program. And since you’re already using containers, why not do this in a container as well? Save the following to a file name Dockerfile:
|
||||
|
||||
```
|
||||
FROM fedora:29
|
||||
RUN dnf -y install python3
|
||||
RUN pip3 install selenium
|
||||
```
|
||||
|
||||
Then build your container image using Podman, in the same folder as Dockerfile:
|
||||
|
||||
```
|
||||
$ podman build -t selenium-python .
|
||||
```
|
||||
|
||||
To run your program in the container, mount the file containing your Python code as a volume when you run the container:
|
||||
|
||||
```
|
||||
$ podman run -t --rm --network host \
|
||||
-v $(pwd)/browser-test.py:/browser-test.py:z \
|
||||
selenium-python python3 browser-test.py
|
||||
```
|
||||
|
||||
The output should look like this:
|
||||
|
||||
```
|
||||
Loading page...
|
||||
Loaded
|
||||
Done.
|
||||
```
|
||||
|
||||
### What to do next
|
||||
|
||||
The example program above is minimal, and perhaps not that useful. But it barely scratched the surface of what’s possible! Check out the documentation for [Selenium][3] and for the [Python bindings][4]. There you’ll find examples for how to locate elements in a page, handle popups, or fill in forms. Drag and drop is also possible, and of course waiting for various events.
|
||||
|
||||
With a few nice tests implemented, you may want to include the whole thing in your CI/CD pipeline. Luckily enough, this is fairly straightforward since everything was containerized to begin with.
|
||||
|
||||
You may also be interested in setting up a [grid][5] to run the tests in parallel. Not only does this help speed things up, but it also allows you to test several different browsers at the same time.
|
||||
|
||||
### Cleaning up
|
||||
|
||||
When you’re done playing with your containers, you can stop and remove the standalone container with the following commands:
|
||||
|
||||
```
|
||||
$ podman stop server
|
||||
$ podman rm server
|
||||
```
|
||||
|
||||
If you also want to free up disk space, run these commands to remove the images as well:
|
||||
|
||||
```
|
||||
$ podman rmi docker.io/selenium/standalone-firefox
|
||||
$ podman rmi selenium-python fedora:29
|
||||
```
|
||||
|
||||
### Conclusion
|
||||
|
||||
In this post, you’ve seen how easy it is to get started with Selenium using container technology. It allowed you to automate interaction with a website, as well as test the interaction. Podman allowed you to run the containers necessary without super user privileges or the Docker daemon. Finally, the Python bindings let you use normal Python code to interact with the browser.
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://fedoramagazine.org/automate-web-browser-selenium/
|
||||
|
||||
作者：[Lennart Jern][a]
|
||||
选题：[lujun9972][b]
|
||||
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/author/lennartj/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.seleniumhq.org/
|
||||
[2]: https://fedoramagazine.org/running-containers-with-podman/
|
||||
[3]: https://www.seleniumhq.org/docs/
|
||||
[4]: https://selenium-python.readthedocs.io
|
||||
[5]: https://www.seleniumhq.org/docs/07_selenium_grid.jsp
|
||||
@ -1,186 +0,0 @@
|
||||
translating by caixiangyue
|
||||
How To Find The Execution Time Of A Command Or Process In Linux
|
||||
======
|
||||
|
||||
|
||||
You probably know the start time of a command/process and [**how long a process is running**][1] in Unix-like systems. But, how do you when did it end and/or what is the total time taken by the command/process to complete? Well, It’s easy! On Unix-like systems, there is a utility named **‘GNU time’** that is specifically designed for this purpose. Using Time utility, we can easily measure the total execution time of a command or program in Linux operating systems. Good thing is ‘time’ command comes preinstalled in most Linux distributions, so you don’t have to bother with installation.
|
||||
|
||||
### Find The Execution Time Of A Command Or Process In Linux
|
||||
|
||||
To measure the execution time of a command/program, just run.
|
||||
|
||||
```
|
||||
$ /usr/bin/time -p ls
|
||||
```
|
||||
|
||||
Or,
|
||||
|
||||
```
|
||||
$ time ls
|
||||
```
|
||||
|
||||
Sample output:
|
||||
|
||||
```
|
||||
dir1 dir2 file1 file2 mcelog
|
||||
|
||||
real 0m0.007s
|
||||
user 0m0.001s
|
||||
sys 0m0.004s
|
||||
|
||||
$ time ls -a
|
||||
. .bash_logout dir1 file2 mcelog .sudo_as_admin_successful
|
||||
.. .bashrc dir2 .gnupg .profile .wget-hsts
|
||||
.bash_history .cache file1 .local .stack
|
||||
|
||||
real 0m0.008s
|
||||
user 0m0.001s
|
||||
sys 0m0.005s
|
||||
```
|
||||
|
||||
The above commands displays the total execution time of **‘ls’** command. Replace “ls” with any command/process of your choice to find the total execution time.
|
||||
|
||||
Here,
|
||||
|
||||
1. **real** -refers the total time taken by command/program,
|
||||
2. **user** – refers the time taken by the program in user mode,
|
||||
3. **sys** – refers the time taken by the program in kernel mode.
|
||||
|
||||
|
||||
|
||||
We can also limit the command to run only for a certain time as well. Refer the following guide for more details.
|
||||
|
||||
### time vs /usr/bin/time
|
||||
|
||||
As you may noticed, we used two commands **‘time’** and **‘/usr/bin/time’** in the above examples. So, you might wonder what is the difference between them.
|
||||
|
||||
First, let us see what actually ‘time’ is using ‘type’ command. For those who don’t know, the **Type** command is used to find out the information about a Linux command. For more details, refer [**this guide**][2].
|
||||
|
||||
```
|
||||
$ type -a time
|
||||
time is a shell keyword
|
||||
time is /usr/bin/time
|
||||
```
|
||||
|
||||
As you see in the above output, time is both,
|
||||
|
||||
* A keyword built into the BASH shell
|
||||
* An executable file i.e **/usr/bin/time**
|
||||
|
||||
|
||||
|
||||
Since shell keywords take precedence over executable files, when you just run`time`command without full path, you run a built-in shell command. But, When you run `/usr/bin/time`, you run a real **GNU time** program. So, in order to access the real command, you may need to specify its explicit path. Clear, good?
|
||||
|
||||
The built-in ‘time’ shell keyword is available in most shells like BASH, ZSH, CSH, KSH, TCSH etc. The ‘time’ shell keyword has less options than the executables. The only option you can use in ‘time’ keyword is **-p**.
|
||||
|
||||
You know now how to find the total execution time of a given command/process using ‘time’ command. Want to know little bit more about ‘GNU time’ utility? Read on!
|
||||
|
||||
### A brief introduction about ‘GNU time’ program
|
||||
|
||||
The GNU time program runs a command/program with given arguments and summarizes the system resource usage as standard output after the command is completed. Unlike the ‘time’ keyword, the GNU time program not just displays the time used by the command/process, but also other resources like memory, I/O and IPC calls.
|
||||
|
||||
The typical syntax of the Time command is:
|
||||
|
||||
```
|
||||
/usr/bin/time [options] command [arguments...]
|
||||
```
|
||||
|
||||
The ‘options’ in the above syntax refers a set of flags that can be used with time command to perform a particular functionality. The list of available options are given below.
|
||||
|
||||
* **-f, –format** – Use this option to specify the format of output as you wish.
|
||||
* **-p, –portability** – Use the portable output format.
|
||||
* **-o file, –output=FILE** – Writes the output to **FILE** instead of displaying as standard output.
|
||||
* **-a, –append** – Append the output to the FILE instead of overwriting it.
|
||||
* **-v, –verbose** – This option displays the detailed description of the output of the ‘time’ utility.
|
||||
* **–quiet** – This option prevents the time ‘time’ utility to report the status of the program.
|
||||
|
||||
|
||||
|
||||
When using ‘GNU time’ program without any options, you will see output something like below.
|
||||
|
||||
```
|
||||
$ /usr/bin/time wc /etc/hosts
|
||||
9 28 273 /etc/hosts
|
||||
0.00user 0.00system 0:00.00elapsed 66%CPU (0avgtext+0avgdata 2024maxresident)k
|
||||
0inputs+0outputs (0major+73minor)pagefaults 0swaps
|
||||
```
|
||||
|
||||
If you run the same command with the shell built-in keyword ‘time’, the output would be bit different:
|
||||
|
||||
```
|
||||
$ time wc /etc/hosts
|
||||
9 28 273 /etc/hosts
|
||||
|
||||
real 0m0.006s
|
||||
user 0m0.001s
|
||||
sys 0m0.004s
|
||||
```
|
||||
|
||||
Some times, you might want to write the system resource usage output to a file rather than displaying in the Terminal. To do so, use **-o** flag like below.
|
||||
|
||||
```
|
||||
$ /usr/bin/time -o file.txt ls
|
||||
dir1 dir2 file1 file2 file.txt mcelog
|
||||
```
|
||||
|
||||
As you can see in the output, Time utility doesn’t display the output. Because, we write the output to a file named file.txt. Let us have a look at this file:
|
||||
|
||||
```
|
||||
$ cat file.txt
|
||||
0.00user 0.00system 0:00.00elapsed 66%CPU (0avgtext+0avgdata 2512maxresident)k
|
||||
0inputs+0outputs (0major+106minor)pagefaults 0swaps
|
||||
```
|
||||
|
||||
When you use **-o** flag, if there is no file named ‘file.txt’, it will create and write the output in it. If the file.txt is already present, it will overwrite its content.
|
||||
|
||||
You can also append output to the file instead of overwriting it using **-a** flag.
|
||||
|
||||
```
|
||||
$ /usr/bin/time -a file.txt ls
|
||||
```
|
||||
|
||||
The **-f** flag allows the users to control the format of the output as per his/her liking. Say for example, the following command displays output of ‘ls’ command and shows just the user, system, and total time.
|
||||
|
||||
```
|
||||
$ /usr/bin/time -f "\t%E real,\t%U user,\t%S sys" ls
|
||||
dir1 dir2 file1 file2 mcelog
|
||||
0:00.00 real, 0.00 user, 0.00 sys
|
||||
```
|
||||
|
||||
Please be mindful that the built-in shell command ‘time’ doesn’t support all features of GNU time program.
|
||||
|
||||
For more details about GNU time utility, refer the man pages.
|
||||
|
||||
```
|
||||
$ man time
|
||||
```
|
||||
|
||||
To know more about Bash built-in ‘Time’ keyword, run:
|
||||
|
||||
```
|
||||
$ help time
|
||||
```
|
||||
|
||||
And, that’s all for now. Hope this useful.
|
||||
|
||||
More good stuffs to come. Stay tuned!
|
||||
|
||||
Cheers!
|
||||
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.ostechnix.com/how-to-find-the-execution-time-of-a-command-or-process-in-linux/
|
||||
|
||||
作者：[SK][a]
|
||||
选题：[lujun9972][b]
|
||||
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/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.ostechnix.com/find-long-process-running-linux/
|
||||
[2]: https://www.ostechnix.com/the-type-command-tutorial-with-examples-for-beginners/
|
||||
@ -0,0 +1,137 @@
|
||||
3 best practices for continuous integration and deployment
|
||||
======
|
||||
Learn about automating, using a Git repository, and parameterizing Jenkins pipelines.
|
||||
|
||||
|
||||
The article covers three key topics: automating CI/CD configuration, using a Git repository for common CI/CD artifacts, and parameterizing Jenkins pipelines.
|
||||
|
||||
### Terminology
|
||||
|
||||
First things first; let's define a few terms. **CI/CD** is a practice that allows teams to quickly and automatically test, package, and deploy their applications. It is often achieved by leveraging a server called **[Jenkins][1]** , which serves as the CI/CD orchestrator. Jenkins listens to specific inputs (often a Git hook following a code check-in) and, when triggered, kicks off a pipeline.
|
||||
|
||||
A **pipeline** consists of code written by development and/or operations teams that instructs Jenkins which actions to take during the CI/CD process. This pipeline is often something like "build my code, then test my code, and if those tests pass, deploy my application to the next highest environment (usually a development, test, or production environment)." Organizations often have more complex pipelines, incorporating tools such as artifact repositories and code analyzers, but this provides a high-level example.
|
||||
|
||||
Now that we understand the key terminology, let's dive into some best practices.
|
||||
|
||||
### 1\. Automation is key
|
||||
|
||||
To run CI/CD on a PaaS, you need the proper infrastructure to be configured on the cluster. In this example, I will use [OpenShift][2].
|
||||
|
||||
"Hello, World" implementations of this are quite simple to achieve. Simply run **oc new-app jenkins- <persistent/ephemeral>** and voilà, you have a running Jenkins server ready to go. Uses in the enterprise, however, are much more complex. In addition to the Jenkins server, admins will often need to deploy a code analysis tool such as SonarQube and an artifact repository such as Nexus. They will then have to create pipelines to perform CI/CD and Jenkins slaves to reduce the load on the master. Most of these entities are backed by OpenShift resources that need to be created to deploy the desired CI/CD infrastructure.
|
||||
|
||||
Eventually, the manual steps required to deploy your CI/CD components may need to be replicated, and you might not be the person to perform those steps. To ensure the outcome is produced quickly, error-free, and exactly as it was before, an automation method should be incorporated in the way your infrastructure is created. This can be an Ansible playbook, a Bash script, or any other way you would like to automate the deployment of CI/CD infrastructure. I have used [Ansible][3] and the [OpenShift-Applier][4] role to automate my implementations. You may find these tools valuable, or you may find something else that works better for you and your organization. Either way, you'll find that automation significantly reduces the workload required to recreate CI/CD components.
|
||||
|
||||
#### Configuring the Jenkins master
|
||||
|
||||
Outside of general "automation," I'd like to single out the Jenkins master and talk about a few ways admins can take advantage of OpenShift to automate Jenkins configuration. The Jenkins image from the [Red Hat Container Catalog][5] comes packaged with the [OpenShift-Sync plugin][6] installed. In the [video][7], we discuss how this plugin can be used to create Jenkins pipelines and slaves.
|
||||
|
||||
To create a Jenkins pipeline, create an OpenShift BuildConfig similar to this:
|
||||
|
||||
```
|
||||
apiVersion: v1
|
||||
kind: BuildConfig
|
||||
...
|
||||
spec:
|
||||
source:
|
||||
git:
|
||||
ref: master
|
||||
uri: <repository-uri>
|
||||
...
|
||||
strategy:
|
||||
jenkinsPipelineStrategy:
|
||||
jenkinsfilePath: Jenkinsfile
|
||||
type: JenkinsPipeline
|
||||
```
|
||||
|
||||
The OpenShift-Sync plugin will notice that a BuildConfig with the strategy **jenkinsPipelineStrategy** has been created and will convert it into a Jenkins pipeline, pulling from the Jenkinsfile specified by the Git source. An inline Jenkinsfile can also be used instead of pulling from one from a Git repository. See the [documentation][8] for more information.
|
||||
|
||||
To create a Jenkins slave, create an OpenShift ImageStream that starts with the following definition:
|
||||
|
||||
```
|
||||
apiVersion: v1
|
||||
kind: ImageStream
|
||||
metadata:
|
||||
annotations:
|
||||
slave-label: jenkins-slave
|
||||
labels:
|
||||
role: jenkins-slave
|
||||
…
|
||||
```
|
||||
|
||||
Notice the metadata defined in this ImageStream. The OpenShift-Sync plugin will convert any ImageStream with the label **role: jenkins-slave** into a Jenkins slave. The Jenkins slave will be named after the value from the **slave-label** annotation.
|
||||
|
||||
ImageStreams work just fine for simple Jenkins slave configurations, but some teams will find it necessary to configure nitty-gritty details such as resource limits, readiness and liveness probes, and instance caps. This is where ConfigMaps come into play:
|
||||
|
||||
```
|
||||
apiVersion: v1
|
||||
kind: ConfigMap
|
||||
metadata:
|
||||
labels:
|
||||
role: jenkins-slave
|
||||
...
|
||||
data:
|
||||
template1: |-
|
||||
<Kubernetes pod template>
|
||||
```
|
||||
|
||||
Notice that the **role: jenkins-slave** label is still required to convert the ConfigMap into a Jenkins slave. The **Kubernetes pod template** consists of a lengthy bit of XML that will configure every detail to your organization's liking. To view this XML, as well as more information on converting ImageStreams and ConfigMaps into Jenkins slaves, see the [documentation][9].
|
||||
|
||||
Notice with the three examples shown above that none of the operations required an administrator to make manual changes to the Jenkins console. By using OpenShift resources, Jenkins can be configured in a way that is easily automated.
|
||||
|
||||
### 2\. Sharing is caring
|
||||
|
||||
The second best practice is maintaining a Git repository of common CI/CD artifacts. The main idea is to prevent teams from reinventing the wheel. Imagine your team needs to perform a blue/green deployment to an OpenShift environment as part of the pipeline's CD phase. The members of your team responsible for writing the pipeline may not be OpenShift experts, nor may they have the bandwidth to write this functionality from scratch. Luckily, somebody has already written a function that incorporates that functionality in a common CI/CD repository, so your team can use that function instead of spending time writing one.
|
||||
|
||||
To take this a step further, your organization may decide to maintain entire pipelines. You may find that teams are writing pipelines with similar functionality. It would be more efficient for those teams to use a parameterized pipeline from a common repository as opposed to writing their own from scratch.
|
||||
|
||||
### 3\. Less is more
|
||||
|
||||
As I hinted in the previous section, the third and final best practice is to parameterize your CI/CD pipelines. Parameterization will prevent an over-abundance of pipelines, making your CI/CD system easier to maintain. Imagine I have multiple regions where I can deploy my application. Without parameterization, I would need a separate pipeline for each region.
|
||||
|
||||
To parameterize a pipeline written as an OpenShift build config, add the **env** stanza to the configuration:
|
||||
|
||||
```
|
||||
...
|
||||
spec:
|
||||
...
|
||||
strategy:
|
||||
jenkinsPipelineStrategy:
|
||||
env:
|
||||
- name: REGION
|
||||
value: US-West
|
||||
jenkinsfilePath: Jenkinsfile
|
||||
type: JenkinsPipeline
|
||||
```
|
||||
|
||||
With this configuration, I can pass the **REGION** parameter the pipeline to deploy my application to the specified region.
|
||||
|
||||
The [video][7] provides a more substantial case where parameterization is a must. Some organizations decide to split up their CI/CD pipelines into separate CI and CD pipelines, usually, because there is some sort of approval process that happens before deployment. Imagine I have four images and three different environments to deploy to. Without parameterization, I would need 12 CD pipelines to allow all deployment possibilities. This can get out of hand very quickly. To make maintenance of the CD pipeline easier, organizations would find it better to parameterize the image and environment to allow one pipeline to perform the work of many.
|
||||
|
||||
### Summary
|
||||
|
||||
CI/CD at the enterprise level tends to become more complex than many organizations anticipate. Luckily, with Jenkins, there are many ways to seamlessly provide automation of your setup. Maintaining a Git repository of common CI/CD artifacts will also ease the effort, as teams can pull from maintained dependencies instead of writing their own from scratch. Finally, parameterization of your CI/CD pipelines will reduce the number of pipelines that will have to be maintained.
|
||||
|
||||
If you've found other practices you can't do without, please share them in the comments.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/11/best-practices-cicd
|
||||
|
||||
作者：[Austin Dewey][a]
|
||||
选题：[lujun9972][b]
|
||||
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/adewey
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://jenkins.io/
|
||||
[2]: https://www.openshift.com/
|
||||
[3]: https://docs.ansible.com/
|
||||
[4]: https://github.com/redhat-cop/openshift-applier
|
||||
[5]: https://access.redhat.com/containers/?tab=overview#/registry.access.redhat.com/openshift3/jenkins-2-rhel7
|
||||
[6]: https://github.com/openshift/jenkins-sync-plugin
|
||||
[7]: https://www.youtube.com/watch?v=zlL7AFWqzfw
|
||||
[8]: https://docs.openshift.com/container-platform/3.11/dev_guide/dev_tutorials/openshift_pipeline.html#the-pipeline-build-config
|
||||
[9]: https://docs.openshift.com/container-platform/3.11/using_images/other_images/jenkins.html#configuring-the-jenkins-kubernetes-plug-in
|
||||
@ -1,3 +1,5 @@
|
||||
Translating by Jamskr
|
||||
|
||||
How to install a device driver on Linux
|
||||
======
|
||||
Learn how Linux drivers work and how to use them.
|
||||
|
||||
@ -0,0 +1,54 @@
|
||||
How to enter single user mode in SUSE 12 Linux?
|
||||
======
|
||||
Short article to learn how to enter single user mode in SUSE 12 Linux server.
|
||||
|
||||
![How to enter single user mode in SUSE 12 Linux][1]
|
||||
|
||||
In this short article we will walk you through steps which demonstrate how to enter single user mode in SUSE 12 Linux. Single user mode is always preferred when you are troubleshooting major issues with your system. Single user mode disables networking and no other users are logged in, you rule out many situations of multi user system and it helps you in troubleshooting fast. One of the most popular use of single user mode is to [reset forgotten root password][2].
|
||||
|
||||
### 1\. Halt boot process
|
||||
|
||||
First of all you need have console of your machine to get into single user mode. If its VM then VM console, if its physical machine then you need its iLO/serial console connected. Reboot system and halt automatic booting of kernel at grub boot menu by pressing any key.
|
||||
|
||||
![Kernel selection menu at boot in SUSE 12][3]
|
||||
|
||||
### 2\. Edit boot option of kernel
|
||||
|
||||
Once you are on above screen, press `e` on selected kernel (which is normally your preferred latest kernel) to update its boot options. You will see be below screen.
|
||||
|
||||
![grub2 edits in SUSE 12][4]
|
||||
|
||||
Now, scroll down to your booting kernel line and add `init=/bin/bash` at the end of the line as shown below.
|
||||
|
||||
![Edit to boot in single user shell][5]
|
||||
|
||||
### 3\. Boot kernel with edited entry
|
||||
|
||||
Now press `Ctrl-x` or `F10` to boot this edited kernel. Kernel will be booted in single user mode and you will be presented with hash prompt i.e. root access to server. At this point of time, your root file system is mounted in read only mode. So any changes you are doing to system wont be saved.
|
||||
|
||||
Run below command to remount root filesystem as re-writable.
|
||||
|
||||
```
|
||||
kerneltalks:/ # mount -o remount,rw /
|
||||
```
|
||||
|
||||
And you are good to go! Go ahead and do your necessary actions in single user mode. Dont forget to reboot server to boot into normal multiuser mode once you are done.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://kerneltalks.com/howto/how-to-enter-single-user-mode-in-suse-12-linux/
|
||||
|
||||
作者：[kerneltalks][a]
|
||||
选题：[lujun9972][b]
|
||||
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://kerneltalks.com
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://a4.kerneltalks.com/wp-content/uploads/2018/11/How-to-enter-single-user-mode-in-SUSE-12-Linux.png
|
||||
[2]: https://kerneltalks.com/linux/recover-forgotten-root-password-rhel/
|
||||
[3]: https://a1.kerneltalks.com/wp-content/uploads/2018/11/Grub-menu-in-SUSE-12.png
|
||||
[4]: https://a3.kerneltalks.com/wp-content/uploads/2018/11/grub2-editor.png
|
||||
[5]: https://a4.kerneltalks.com/wp-content/uploads/2018/11/Edit-to-boot-in-single-user-shell.png
|
||||
@ -1,98 +1,160 @@
|
||||
Lisp 是怎么成为上帝的编程语言的
|
||||
======
|
||||
|
||||
当程序员们谈论各类编程语言的相对优势时，他们通常会采用相当平淡的词措，就好像这些语言是一条工具带上的各种工具似的——有适合写操作系统的，也有适合把其它程序黏在一起来完成特殊工作的。这种讨论方式非常合理；不同语言的能力不同。不声明特定用途就声称某门语言比其他语言更优秀只能导致侮辱性的无用争论。
|
||||
当程序员们谈论各类编程语言的相对优势时，他们通常会采用相当平淡的措词，就好像这些语言是一条工具带上的各种工具似的 —— 有适合写操作系统的，也有适合把其它程序黏在一起来完成特殊工作的。这种讨论方式非常合理；不同语言的能力不同。不声明特定用途就声称某门语言比其他语言更优秀只能导致侮辱性的无用争论。
|
||||
|
||||
但有一门语言似乎受到和用途无关的特殊尊敬：那就是 Lisp。即使是恨不得给每个说出形如“某某语言比其他所有语言都好”这类话的人都来一拳的键盘远征军们，也会承认Lisp处于另一个层次。 Lisp 超越了用于评判其他语言的实用主义标准，因为普通程序员并不使用 Lisp 编写实用的程序 —— 而且，多半他们永远也不会这么做。然而，人们对 Lisp 的敬意是如此深厚，甚至于到了这门语言会时而被加上神话属性的程度。大家都喜欢的网络漫画合集 xkcd 就至少在两组漫画中如此描绘过 Lisp：[其中一组漫画][1]中，一个人物得到了某种 Lisp 启示，而这好像使他理解了宇宙的基本构架。在[另一组漫画][2]中，一个穿着长袍的老程序员给他的徒弟递了一沓圆括号，说这是“文明时代的优雅武器”，暗示着 Lisp 就像原力那样拥有各式各样的神秘力量。
|
||||
但有一门语言似乎受到和用途无关的特殊尊敬：那就是 Lisp。即使是恨不得给每个说出形如“某某语言比其他所有语言都好”这类话的人都来一拳的键盘远征军们，也会承认 Lisp 处于另一个层次。 Lisp 超越了用于评判其他语言的实用主义标准，因为普通程序员并不使用 Lisp 编写实用的程序 —— 而且，多半他们永远也不会这么做。然而，人们对 Lisp 的敬意是如此深厚，甚至于到了这门语言会时而被加上神话属性的程度。
|
||||
|
||||
大家都喜欢的网络漫画合集 xkcd 就至少在两组漫画中如此描绘过 Lisp：[其中一组漫画][1]中，某人得到了某种 Lisp 启示，而这好像使他理解了宇宙的基本构架。
|
||||
|
||||
|
||||
|
||||
在[另一组漫画][2]中，一个穿着长袍的老程序员给他的徒弟递了一沓圆括号，说这是“文明时代的优雅武器”，暗示着 Lisp 就像原力那样拥有各式各样的神秘力量。
|
||||
|
||||
|
||||
|
||||
另一个绝佳例子是 Bob Kanefsky 的滑稽剧插曲，《上帝就在人间》。这部剧叫做《永恒之火》，编写于 1990 年代中期；剧中描述了上帝必然是使用 Lisp 创造世界的种种原因。完整的歌词可以在 [GNU 幽默合集][3]中找到，如下是一段摘抄：
|
||||
|
||||
> 因为上帝用祂的 Lisp 代码
|
||||
另一个绝佳例子是 Bob Kanefsky 的滑稽剧插曲，《上帝就在人间》。这部剧叫做《永恒之火》，撰写于 1990 年代中期；剧中描述了上帝必然是使用 Lisp 创造世界的种种原因。完整的歌词可以在 [GNU 幽默合集][3]中找到，如下是一段摘抄：
|
||||
|
||||
> 因为上帝用祂的 Lisp 代码
|
||||
|
||||
> 让树叶充满绿意。
|
||||
|
||||
|
||||
> 分形的花儿和递归的根：
|
||||
|
||||
> 我见过的奇技淫巧（hack）之中没什么比这更可爱。
|
||||
|
||||
|
||||
> 我见过的奇技淫巧之中没什么比这更可爱。
|
||||
|
||||
> 当我对着雪花深思时，
|
||||
|
||||
|
||||
> 从未见过两片相同的，
|
||||
|
||||
|
||||
> 我知道，上帝偏爱那一门
|
||||
|
||||
|
||||
> 名字是四个字母的语言。
|
||||
|
||||
以下这句话我实在不好在人前说；不过，我还是觉得，这样一种“ Lisp 是奥术魔法”的文化模因实在是有史以来最奇异、最迷人的东西。 Lisp 是象牙塔的产物，是人工智能研究的工具；因此，它对于编程界的俗人而言总是陌生的，甚至是带有神秘色彩的。然而，当今的程序员们开始怂恿彼此，[“在你死掉之前至少试一试 Lisp ”][4]，就像这是一种令人恍惚入迷的致幻剂似的。尽管 Lisp 是广泛使用的编程语言中第二古老的（只比 Fortran 年轻一岁），程序员们也仍旧在互相怂恿。想象一下，如果你的工作是为某种组织或者团队推广一门新的编程语言的话，忽悠大家让他们相信你的新语言拥有神力难道不是绝佳的策略吗？——但你如何能够做到这一点呢？或者，换句话说，一门编程语言究竟是如何变成人们口中“隐晦知识的载体”的呢？
|
||||
以下这句话我实在不好在人前说；不过，我还是觉得，这样一种 “Lisp 是奥术魔法”的文化模因实在是有史以来最奇异、最迷人的东西。Lisp 是象牙塔的产物，是人工智能研究的工具；因此，它对于编程界的俗人而言总是陌生的，甚至是带有神秘色彩的。然而，当今的程序员们[开始怂恿彼此，“在你死掉之前至少试一试 Lisp”][4]，就像这是一种令人恍惚入迷的致幻剂似的。尽管 Lisp 是广泛使用的编程语言中第二古老的（只比 Fortran 年轻一岁）[^1] ，程序员们也仍旧在互相怂恿。想象一下，如果你的工作是为某种组织或者团队推广一门新的编程语言的话，忽悠大家让他们相信你的新语言拥有神力难道不是绝佳的策略吗？—— 但你如何能够做到这一点呢？或者，换句话说，一门编程语言究竟是如何变成人们口中“隐晦知识的载体”的呢？
|
||||
|
||||
Lisp 究竟是怎么成为这样的？
|
||||
|
||||
![Byte 杂志封面,1979年八月。][5] Byte 杂志封面，1979年八月。
|
||||
![Byte 杂志封面,1979年八月。][5]
|
||||
|
||||
*Byte 杂志封面，1979年八月。*
|
||||
|
||||
### 理论 A ：公理般的语言
|
||||
|
||||
Lisp 的创造者 John McCarthy 最初并没有想过把 Lisp 做成优雅、精炼的计算法则结晶。然而，在一两次运气使然的深谋远虑和一系列优化之后， Lisp 的确变成了那样的东西。 Paul Graham —— 我们一会儿之后才会聊到他 —— 曾经这么写，说， McCarthy 通过 Lisp “为编程作出的贡献就像是欧几里得对几何学所做的贡献一般”。人们可能会在 Lisp 中看出更加隐晦的含义——因为 McCarthy 创造 Lisp 时使用的要素实在是过于基础，基础到连弄明白他到底是创造了这门语言、还是发现了这门语言，都是一件难事。
|
||||
Lisp 的创造者<ruby>约翰·麦卡锡<rt>John McCarthy</rt></ruby>最初并没有想过把 Lisp 做成优雅、精炼的计算法则结晶。然而，在一两次运气使然的深谋远虑和一系列优化之后，Lisp 的确变成了那样的东西。 <ruby>保罗·格雷厄姆<rt>Paul Graham</rt></ruby>（我们一会儿之后才会聊到他）曾经这么写道， 麦卡锡通过 Lisp “为编程作出的贡献就像是欧几里得对几何学所做的贡献一般” [^2]。人们可能会在 Lisp 中看出更加隐晦的含义 —— 因为麦卡锡创造 Lisp 时使用的要素实在是过于基础，基础到连弄明白他到底是创造了这门语言、还是发现了这门语言，都是一件难事。
|
||||
|
||||
最初， McCarthy 产生要造一门语言的想法，是在 1956 年的达特茅斯人工智能夏季研究项目（Darthmouth Summer Research Project on Artificial Intelligence）上。夏季研究项目是个持续数周的学术会议，直到现在也仍旧在举行；它是此类会议之中最早开始举办的会议之一。 McCarthy 当初还是个达特茅斯的数学助教，而“人工智能”这个词事实上就是他建议举办会议时发明的。在整个会议期间大概有十人参加。他们之中包括了 Allen Newell 和 Herbert Simon ，两名隶属于兰德公司和卡内基梅隆大学的学者。这两人不久之前设计了一门语言，叫做IPL。
|
||||
最初， 麦卡锡产生要造一门语言的想法，是在 1956 年的<ruby>达特茅斯人工智能夏季研究项目<rt>Darthmouth Summer Research Project on Artificial Intelligence</rt></ruby>上。夏季研究项目是个持续数周的学术会议，直到现在也仍旧在举行；它是此类会议之中最早开始举办的会议之一。 麦卡锡当初还是个达特茅斯的数学助教，而“<ruby>人工智能<rt>artificial intelligence</rt></ruby>（AI）”这个词事实上就是他建议举办该会议时发明的 [^3]。在整个会议期间大概有十人参加 [^4]。他们之中包括了<ruby>艾伦·纽厄尔<rt>Allen Newell</rt></ruby>和<ruby>赫伯特·西蒙<rt>Herbert Simon</rt></ruby>，两名隶属于<ruby>兰德公司<rt>RAND Corporation</rt></ruby>和<ruby>卡内基梅隆大学<rt>Carnegie Mellon</rt></ruby>的学者。这两人不久之前设计了一门语言，叫做 IPL。
|
||||
|
||||
当时，Newell 和 Simon 正试图制作一套能够在命题演算中生成证明的系统。两人意识到，用电脑的原生指令集编写这套系统会非常困难；于是他们决定创造一门语言——原话是“伪代码”，这样，他们就能更加轻松自然地表达这台“逻辑理论机器”的底层逻辑了。这门语言叫做IPL，即“信息处理语言” (Information Processing Language) ；比起我们现在认知中的编程语言，它更像是一种汇编语言的方言。 Newell 和 Simon 提到，当时人们开发的其它“伪代码”都抓着标准数学符号不放——也许他们指的是 Fortran；与此不同的是，他们的语言使用成组的符号方程来表示命题演算中的语句。通常，用 IPL 写出来的程序会调用一系列的汇编语言宏，以此在这些符号方程列表中对表达式进行变换和求值。
|
||||
当时，纽厄尔和西蒙正试图制作一套能够在命题演算中生成证明的系统。两人意识到，用电脑的原生指令集编写这套系统会非常困难；于是他们决定创造一门语言——他们的原话是“<ruby>伪代码<rt>pseudo-code</rt></ruby>”，这样，他们就能更加轻松自然地表达这台“<ruby>逻辑理论机器<rt>Logic Theory Machine</rt></ruby>”的底层逻辑了 [^5]。这门语言叫做 IPL，即“<ruby>信息处理语言<rt>Information Processing Language</rt></ruby>”；比起我们现在认知中的编程语言，它更像是一种高层次的汇编语言方言。 纽厄尔和西蒙提到，当时人们开发的其它“伪代码”都抓着标准数学符号不放 —— 也许他们指的是 Fortran [^6]；与此不同的是，他们的语言使用成组的符号方程来表示命题演算中的语句。通常，用 IPL 写出来的程序会调用一系列的汇编语言宏，以此在这些符号方程列表中对表达式进行变换和求值。
|
||||
|
||||
McCarthy 认为，一门实用的编程语言应该像 Fortran 那样使用代数表达式；因此，他并不怎么喜欢 IPL 。然而，他也认为，在给人工智能领域的一些问题建模时，符号列表会是非常好用的工具——而且在那些涉及演绎的问题上尤其有用。 McCarthy 的渴望最终被诉诸行动；他要创造一门代数的列表处理语言——这门语言会像 Fortran 一样使用代数表达式，但拥有和 IPL 一样的符号列表处理能力。
|
||||
麦卡锡认为，一门实用的编程语言应该像 Fortran 那样使用代数表达式；因此，他并不怎么喜欢 IPL [^7]。然而，他也认为，在给人工智能领域的一些问题建模时，符号列表会是非常好用的工具 —— 而且在那些涉及演绎的问题上尤其有用。麦卡锡的渴望最终被诉诸行动；他要创造一门代数的列表处理语言 —— 这门语言会像 Fortran 一样使用代数表达式，但拥有和 IPL 一样的符号列表处理能力。
|
||||
|
||||
当然，今日的 Lisp 可不像 Fortran。在会议之后的几年中， McCarthy 关于“理想的列表处理语言”的见解似乎在逐渐演化。到 1957 年，他的想法发生了改变。他那时候正在用 Fortran 编写一个能下象棋的程序；越是长时间地使用 Fortran ， McCarthy 就越确信其设计中存在不当之处，而最大的问题就是尴尬的“ IF ”声明。为此，他发明了一个替代品，即条件表达式“ true ”；这个表达式会在给定的测试通过时返回子表达式 A ，而在测试未通过时返回子表达式 B ，而且，它只会对返回的子表达式进行求值。在 1958 年夏天，当 McCarthy 设计一个能够求导的程序时，他意识到，他发明的“true”表达式让编写递归函数这件事变得更加简单自然了。也是这个求导问题让 McCarthy 创造了 maplist 函数；这个函数会将其它函数作为参数并将之作用于指定列表的所有元素。在给项数多得叫人抓狂的多项式求导时，它尤其有用。
|
||||
当然，今日的 Lisp 可不像 Fortran。在会议之后的几年中，麦卡锡关于“理想的列表处理语言”的见解似乎在逐渐演化。到 1957 年，他的想法发生了改变。他那时候正在用 Fortran 编写一个能下国际象棋的程序；越是长时间地使用 Fortran ，麦卡锡就越确信其设计中存在不当之处，而最大的问题就是尴尬的 `IF` 声明 [^8]。为此，他发明了一个替代品，即条件表达式 `true`；这个表达式会在给定的测试通过时返回子表达式 `A` ，而在测试未通过时返回子表达式 `B` ，*而且*，它只会对返回的子表达式进行求值。在 1958 年夏天，当麦卡锡设计一个能够求导的程序时，他意识到，他发明的 `true` 条件表达式让编写递归函数这件事变得更加简单自然了 [^9]。也是这个求导问题让麦卡锡创造了 `maplist` 函数；这个函数会将其它函数作为参数并将之作用于指定列表的所有元素 [^10]。在给项数多得叫人抓狂的多项式求导时，它尤其有用。
|
||||
|
||||
然而，以上的所有这些，在 Fortran 中都是没有的；因此，在1958年的秋天，McCarthy 请来了一群学生来实现 Lisp。因为他那时已经成了一名麻省理工助教，所以，这些学生可都是麻省理工的学生。当 McCarthy 和学生们最终将他的主意变为能运行的代码时，这门语言得到了进一步的简化。这之中最大的改变涉及了 Lisp 的语法本身。最初，McCarthy 在设计语言时，曾经试图加入所谓的“M 表达式”；这是一层语法糖，能让 Lisp 的语法变得类似于 Fortran。虽然 M 表达式可以被翻译为 S 表达式 —— 基础的、“用圆括号括起来的列表”，也就是 Lisp 最著名的特征 —— 但 S 表达式事实上是一种给机器看的低阶表达方法。唯一的问题是，McCarthy 用方括号标记 M 表达式，但他的团队在麻省理工使用的 IBM 026 键盘打孔机的键盘上根本没有方括号。于是 Lisp 团队坚定不移地使用着 S 表达式，不仅用它们表示数据列表，也拿它们来表达函数的应用。McCarthy 和他的学生们还作了另外几样改进，包括将数学符号前置；他们也修改了内存模型，这样 Lisp 实质上就只有一种数据类型了。
|
||||
然而，以上的所有这些，在 Fortran 中都是没有的；因此，在 1958 年的秋天，麦卡锡请来了一群学生来实现 Lisp。因为他那时已经成了一名麻省理工助教，所以，这些学生可都是麻省理工的学生。当麦卡锡和学生们最终将他的主意变为能运行的代码时，这门语言得到了进一步的简化。这之中最大的改变涉及了 Lisp 的语法本身。最初，麦卡锡在设计语言时，曾经试图加入所谓的 “M 表达式”；这是一层语法糖，能让 Lisp 的语法变得类似于 Fortran。虽然 M 表达式可以被翻译为 S 表达式 —— 基础的、“用圆括号括起来的列表”，也就是 Lisp 最著名的特征 —— 但 S 表达式事实上是一种给机器看的低阶表达方法。唯一的问题是，麦卡锡用方括号标记 M 表达式，但他的团队在麻省理工使用的 IBM 026 键盘打孔机的键盘上根本没有方括号 [^11]。于是 Lisp 团队坚定不移地使用着 S 表达式，不仅用它们表示数据列表，也拿它们来表达函数的应用。麦卡锡和他的学生们还作了另外几样改进，包括将数学符号前置；他们也修改了内存模型，这样 Lisp 实质上就只有一种数据类型了 [^12]。
|
||||
|
||||
到 1960 年，McCarthy 发表了他关于 Lisp 的著名论文，《用符号方程表示的递归函数及它们的机器计算》。那时候，Lisp 已经被极大地精简，而这让 McCarthy 意识到，他的作品其实是“一套优雅的数学系统”，而非普通的编程语言。他之后这么写道，对 Lisp 的许多简化使其“成了一种描述可计算函数的方式，而且它比图灵机或者一般情况下用于递归函数理论的递归定义更加简洁”。在他的论文中，他不仅使用 Lisp 作为编程语言，也将它当作一套用于研究递归函数行为方式的表达方法。
|
||||
到 1960 年，麦卡锡发表了他关于 Lisp 的著名论文，《用符号方程表示的递归函数及它们的机器计算》。那时候，Lisp 已经被极大地精简，而这让麦卡锡意识到，他的作品其实是“一套优雅的数学系统”，而非普通的编程语言 [^13]。他后来这么写道，对 Lisp 的许多简化使其“成了一种描述可计算函数的方式，而且它比图灵机或者一般情况下用于递归函数理论的递归定义更加简洁” [^14]。在他的论文中，他不仅使用 Lisp 作为编程语言，也将它当作一套用于研究递归函数行为方式的表达方法。
|
||||
|
||||
通过“从一小撮规则中逐步实现出 Lisp”的方式，McCarthy 将这门语言介绍给了他的读者。不久之后，Paul Graham 换用更加易读的写法，在短文[《Lisp 之根》][6]（The Roots of Lisp）中再次进行了介绍。在 Graham 的介绍中，他只用了七种基本的运算符、两种函数写法，和几个稍微高级一点的函数（也都使用基本运算符进行定义）。毫无疑问，Lisp 的这种只需使用极少量的基本规则就能完整说明的特点加深了其神秘色彩。Graham 称 McCarthy 的论文为“使计算公理化”的一种尝试。我认为，在思考 Lisp 的魅力从何而来时，这是一个极好的切入点。其它编程语言都有明显的人工构造痕迹，表现为“While”，“typedef”，“public static void”这样的关键词；而 Lisp 的设计却简直像是纯粹计算逻辑的鬼斧神工。Lisp 的这一性质，以及它和晦涩难懂的“递归函数理论”的密切关系，使它具备了获得如今声望的充分理由。
|
||||
通过“从一小撮规则中逐步实现出 Lisp”的方式，麦卡锡将这门语言介绍给了他的读者。后来，保罗·格雷厄姆在短文《<ruby>[Lisp 之根][6]<rt>The Roots of Lisp</rt></ruby>》中用更易读的语言回顾了麦卡锡的步骤。格雷厄姆只用了七种原始运算符、两种函数写法，以及使用原始运算符定义的六个稍微高级一点的函数来解释 Lisp。毫无疑问，Lisp 的这种只需使用极少量的基本规则就能完整说明的特点加深了其神秘色彩。格雷厄姆称麦卡锡的论文为“使计算公理化”的一种尝试 [^15]。我认为，在思考 Lisp 的魅力从何而来时，这是一个极好的切入点。其它编程语言都有明显的人工构造痕迹，表现为 `While`，`typedef`，`public static void` 这样的关键词；而 Lisp 的设计却简直像是纯粹计算逻辑的鬼斧神工。Lisp 的这一性质，以及它和晦涩难懂的“递归函数理论”的密切关系，使它具备了获得如今声望的充分理由。
|
||||
|
||||
### 理论 B：属于未来的机器
|
||||
|
||||
Lisp 诞生二十年后，它成了著名的《黑客词典》中所说的，人工智能研究的“母语”。Lisp 在此之前传播迅速，多半是托了语法规律的福 —— 不管在怎么样的电脑上，实现 Lisp 都是一件相对简单直白的事。而学者们之后坚持使用它乃是因为 Lisp 在处理符号表达式这方面有巨大的优势；在那个时代，人工智能很大程度上就意味着符号，于是这一点就显得十分重要。在许多重要的人工智能项目中都能见到 Lisp 的身影。这些项目包括了 [SHRDLU 自然语言程序][8]（the SHRDLU natural language program），[Macsyma 代数系统][9]（the Macsyma algebra system），和 [ACL2 逻辑系统][10]（the ACL2 logic system）。
|
||||
Lisp 诞生二十年后，它成了著名的《<ruby>[黑客词典][7]<rt>Hacker’s Dictionary</rt></ruby>》中所说的，人工智能研究的“母语”。Lisp 在此之前传播迅速，多半是托了语法规律的福 —— 不管在怎么样的电脑上，实现 Lisp 都是一件相对简单直白的事。而学者们之后坚持使用它乃是因为 Lisp 在处理符号表达式这方面有巨大的优势；在那个时代，人工智能很大程度上就意味着符号，于是这一点就显得十分重要。在许多重要的人工智能项目中都能见到 Lisp 的身影。这些项目包括了 [SHRDLU 自然语言程序][8]、[Macsyma 代数系统][9] 和 [ACL2 逻辑系统][10]。
|
||||
|
||||
然而，在 1970 年代中期，人工智能研究者们的电脑算力开始不够用了。PDP-10 就是一个典型。这个型号在人工智能学界曾经极受欢迎；但面对这些用 Lisp 写的 AI 程序，它的 18 位内存空间一天比一天显得吃紧。许多的 AI 程序在设计上可以与人互动。要让这些既极度要求硬件性能、又有互动功能的程序在分时系统上优秀发挥，是很有挑战性的。麻省理工的 Peter Deutsch 给出了解决方案：那就是针对 Lisp 程序来特别设计电脑。就像是我那[关于 Chaosnet 的上一篇文章][11]所说的那样，这些 Lisp 计算机（Lisp machines)会给每个用户都专门分配一个为 Lisp 特别优化的处理器。到后来，考虑到硬核 Lisp 程序员的需求，这些计算机甚至还配备上了完全由 Lisp 编写的开发环境。在当时那样一个小型机时代已至尾声而微型机的繁盛尚未完全到来的尴尬时期，Lisp 计算机就是编程精英们的“高性能个人电脑”。
|
||||
然而，在 1970 年代中期，人工智能研究者们的电脑算力开始不够用了。PDP-10 就是一个典型。这个型号在人工智能学界曾经极受欢迎；但面对这些用 Lisp 写的 AI 程序，它的 18 位地址空间一天比一天显得吃紧 [^16]。许多的 AI 程序在设计上可以与人互动。要让这些既极度要求硬件性能、又有互动功能的程序在分时系统上优秀发挥，是很有挑战性的。麻省理工的<ruby>彼得·杜奇<rt>Peter Deutsch</rt></ruby>给出了解决方案：那就是针对 Lisp 程序来特别设计电脑。就像是我那[关于 Chaosnet 的上一篇文章][11]所说的那样，这些<ruby>Lisp 计算机<rt>Lisp machines</rt></ruby>会给每个用户都专门分配一个为 Lisp 特别优化的处理器。到后来，考虑到硬核 Lisp 程序员的需求，这些计算机甚至还配备上了完全由 Lisp 编写的开发环境。在当时那样一个小型机时代已至尾声而微型机的繁盛尚未完全到来的尴尬时期，Lisp 计算机就是编程精英们的“高性能个人电脑”。
|
||||
|
||||
有那么一会儿，Lisp 计算机被当成是未来趋势。好几家公司无中生有地出现，追着赶着要把这项技术商业化。其中最成功的一家叫做 Symbolics，由麻省理工 AI 实验室的前成员创立。上世纪八十年代，这家公司生产了所谓的 3600 系列计算机，它们当时在 AI 领域和需要高性能计算的产业中应用极广。3600 系列配备了大屏幕、位图显示、鼠标接口，以及[强大的图形与动画软件][12]。它们都是惊人的机器，能让惊人的程序运行起来。例如，之前在推特上跟我聊过的机器人研究者 Bob Culley，就能用一台 1985 年生产的 Symbolics 3650 写出带有图形演示的寻路算法。他向我解释说，在 1980 年代，位图显示和面向对象编程（能够通过 [Flavors 扩展][13]在 Lisp 计算机上使用）都刚刚出现。Symbolics 站在时代的最前沿。
|
||||
有那么一会儿，Lisp 计算机被当成是未来趋势。好几家公司雨后春笋般出现，追着赶着要把这项技术商业化。其中最成功的一家叫做 Symbolics，由麻省理工 AI 实验室的前成员创立。上世纪八十年代，这家公司生产了所谓的 3600 系列计算机，它们当时在 AI 领域和需要高性能计算的产业中应用极广。3600 系列配备了大屏幕、位图显示、鼠标接口，以及[强大的图形与动画软件][12]。它们都是惊人的机器，能让惊人的程序运行起来。例如，之前在推特上跟我聊过的机器人研究者 Bob Culley，就能用一台 1985 年生产的 Symbolics 3650 写出带有图形演示的寻路算法。他向我解释说，在 1980 年代，位图显示和面向对象编程（能够通过 [Flavors 扩展][13]在 Lisp 计算机上使用）都刚刚出现。Symbolics 站在时代的最前沿。
|
||||
|
||||
![Bob Culley 的寻路程序。][14] Bob Culley 的寻路程序。
|
||||
![Bob Culley 的寻路程序。][14]
|
||||
|
||||
*Bob Culley 的寻路程序。*
|
||||
|
||||
而以上这一切导致 Symbolics 的计算机奇贵无比。在 1983 年，一台 Symbolics 3600 能卖 111,000 美金。所以，绝大部分人只可能远远地赞叹 Lisp 计算机的威力，和操作员们用 Lisp 编写程序的奇妙技术 —— 但他们的确发出了赞叹。从 1979 年到 1980 年代末，Byte 杂志曾经多次提到过 Lisp 和 Lisp 计算机。在 1979 年八月发行的、关于 Lisp 的一期特别杂志中，杂志编辑激情洋溢地写道，麻省理工正在开发的计算机配备了“大坨大坨的内存”和“先进的操作系统”；他觉得，这些 Lisp 计算机的前途是如此光明，以至于它们的面世会让 1978 和 1977 年 —— 诞生了 Apple II, Commodore PET，和TRS-80 的两年 —— 显得黯淡无光。五年之后，在1985年，一名 Byte 杂志撰稿人描述了为“复杂精巧、性能强悍的 Symbolics 3670”编写 Lisp 程序的体验，并力劝读者学习 Lisp，称其为“绝大数人工智能工作者的语言选择”，和将来的通用编程语言。
|
||||
而以上这一切导致 Symbolics 的计算机奇贵无比。在 1983 年，一台 Symbolics 3600 能卖 111,000 美金 [^16]。所以，绝大部分人只可能远远地赞叹 Lisp 计算机的威力，和它们那些用 Lisp 编写的操作符的巫术。不止他们赞叹，从 1979 年到 1980 年代末，Byte 杂志曾经多次提到过 Lisp 和 Lisp 计算机。在 1979 年八月发行的、关于 Lisp 的一期特别杂志中，杂志编辑激情洋溢地写道，麻省理工正在开发的计算机配备了“大坨大坨的内存”和“先进的操作系统” [^17]；他觉得，这些 Lisp 计算机的前途是如此光明，以至于它们的面世会让 1978 和 1977 年 —— 诞生了 Apple II、Commodore PET 和 TRS-80 的两年 —— 显得黯淡无光。五年之后，在 1985 年，一名 Byte 杂志撰稿人描述了为“复杂精巧、性能强悍的 Symbolics 3670”编写 Lisp 程序的体验，并力劝读者学习 Lisp，称其为“绝大数人工智能工作者的语言选择”，和将来的通用编程语言 [^18]。
|
||||
|
||||
我问过 Paul McJones [他在山景（Mountain View）的计算机历史博物馆做了许多 Lisp 的[保存工作][15]]，人们是什么时候开始将 Lisp 当作高维生物的赠礼一样谈论的呢？他说，这门语言自有的性质毋庸置疑地促进了这种现象的产生；然而，他也说，Lisp 上世纪六七十年代在人工智能领域得到的广泛应用，很有可能也起到了作用。当 1980 年代到来、Lisp 计算机进入市场时，象牙塔外的某些人由此接触到了 Lisp 的能力，于是传说开始滋生。时至今日，很少有人还记得 Lisp 计算机和 Symbolics 公司；但 Lisp 得以在八十年代一直保持神秘，很大程度上要归功于它们。
|
||||
我问过<ruby>保罗·麦克琼斯<rt>Paul McJones</rt></ruby>（他在<ruby>山景城<rt>Mountain View<rt></ruby>的<ruby>计算机历史博物馆<rt>Computer History Museum</rt></ruby>做了许多 Lisp 的[保护工作][15]），人们是什么时候开始将 Lisp 当作高维生物的赠礼一样谈论的呢？他说，这门语言自有的性质毋庸置疑地促进了这种现象的产生；然而，他也说，Lisp 上世纪六七十年代在人工智能领域得到的广泛应用，很有可能也起到了作用。当 1980 年代到来、Lisp 计算机进入市场时，象牙塔外的某些人由此接触到了 Lisp 的能力，于是传说开始滋生。时至今日，很少有人还记得 Lisp 计算机和 Symbolics 公司；但 Lisp 得以在八十年代一直保持神秘，很大程度上要归功于它们。
|
||||
|
||||
### 理论 C：学习编程
|
||||
|
||||
1985 年，两位麻省理工的教授，Harold Abelson 和 Gerald Sussman，外加 Sussman 的妻子，出版了一本叫做《计算机程序的构造和解释》（Structure and Interpretation of Computer Programs）的教科书。这本书用 Scheme（一种 Lisp 方言）向读者们示范如何编程。它被用于教授麻省理工入门编程课程长达二十年之久。出于直觉，我认为 SICP（这是通常而言的标题缩写）倍增了 Lisp 的“神秘要素”。SICP 使用 Lisp 描绘了深邃得几乎可以称之为哲学的编程理念。这些理念非常普适，可以用任意一种编程语言展现；但 SICP 的作者们选择了 Lisp。结果，这本阴阳怪气、卓越不凡、吸引了好几代程序员（还成了一种[奇特的模因][16]）的著作臭名远扬之后，Lisp 的声望也顺带被提升了。Lisp 已不仅仅是一如既往的“McCarthy 的优雅表达方式”；它现在还成了“向你传授编程的不传之秘的语言”。
|
||||
1985 年，两位麻省理工的教授，<ruby>哈尔·阿伯尔森<rt>Harold "Hal" Abelson</rt></ruby>和<ruby>杰拉尔德·瑟斯曼<rt>Gerald Sussman</rt></ruby>，外加瑟斯曼的妻子<ruby>朱莉·瑟斯曼<rt>Julie Sussman</rt></ruby>，出版了一本叫做《<ruby>计算机程序的构造和解释<rt>Structure and Interpretation of Computer Programs</rt></ruby>》的教科书。这本书用 Scheme（一种 Lisp 方言）向读者们示范了如何编程。它被用于教授麻省理工入门编程课程长达二十年之久。出于直觉，我认为 SICP（这本书的名字通常缩写为 SICP）倍增了 Lisp 的“神秘要素”。SICP 使用 Lisp 描绘了深邃得几乎可以称之为哲学的编程理念。这些理念非常普适，可以用任意一种编程语言展现；但 SICP 的作者们选择了 Lisp。结果，这本阴阳怪气、卓越不凡、吸引了好几代程序员（还成了一种[奇特的模因][16]）的著作臭名远扬之后，Lisp 的声望也顺带被提升了。Lisp 已不仅仅是一如既往的“麦卡锡的优雅表达方式”；它现在还成了“向你传授编程的不传之秘的语言”。
|
||||
|
||||
SICP 究竟有多奇怪这一点值得好好说；因为我认为，时至今日，这本书的古怪之处和 Lisp 的古怪之处是相辅相成的。书的封面就透着一股古怪。那上面画着一位朝着桌子走去，准备要施法的巫师或者炼金术士。他的一只手里抓着一副测径仪 —— 或者圆规，另一只手上拿着个球，上书“eval”和“apply”。他对面的女人指着桌子；在背景中，希腊字母λ漂浮在半空，释放出光芒。
|
||||
SICP 究竟有多奇怪这一点值得好好说；因为我认为，时至今日，这本书的古怪之处和 Lisp 的古怪之处是相辅相成的。书的封面就透着一股古怪。那上面画着一位朝着桌子走去，准备要施法的巫师或者炼金术士。他的一只手里抓着一副测径仪 —— 或者圆规，另一只手上拿着个球，上书“eval”和“apply”。他对面的女人指着桌子；在背景中，希腊字母 λ （lambda）漂浮在半空，释放出光芒。
|
||||
|
||||
![SICP 封面上的画作][17] SICP 封面上的画作。
|
||||
![SICP 封面上的画作][17]
|
||||
|
||||
*SICP 封面上的画作。*
|
||||
|
||||
说真的，这上面画的究竟是怎么一回事？为什么桌子会长着动物的腿？为什么这个女人指着桌子？墨水瓶又是干什么用的？我们是不是该说，这位巫师已经破译了宇宙的隐藏奥秘，而所有这些奥秘就蕴含在 eval/apply 循环和 Lambda 微积分之中？看似就是如此。单单是这张图片，就一定对人们如今谈论 Lisp 的方式产生了难以计量的影响。
|
||||
|
||||
然而，这本书的内容通常并不比封面正常多少。SICP 跟你读过的所有计算机科学教科书都不同。在引言中，作者们表示，这本书不只教你怎么用 Lisp 编程 —— 它是关于“现象的三个焦点：人的心智，复数的计算机程序，和计算机”的作品。在之后，他们对此进行了解释，描述了他们对如下观点的坚信：编程不该被当作是一种计算机科学的训练，而应该是“程序性认识论”的一种新表达方式。程序是将那些偶然被送入计算机的思想组织起来的全新方法。这本书的第一章简明地介绍了 Lisp，但是之后的绝大部分都在讲述更加抽象的概念。其中包括了对不同编程范式的讨论，对于面向对象系统中“时间”和“一致性”的讨论；在书中的某一处，还有关于通信的基本限制可能会如何带来同步问题的讨论 —— 而这些基本限制在通信中就像是光速不变在相对中一样关键。都是些高深难懂的东西。
|
||||
然而，这本书的内容通常并不比封面正常多少。SICP 跟你读过的所有计算机科学教科书都不同。在引言中，作者们表示，这本书不只教你怎么用 Lisp 编程 —— 它是关于“现象的三个焦点：人的心智、复数的计算机程序，和计算机”的作品 [^19]。在之后，他们对此进行了解释，描述了他们对如下观点的坚信：编程不该被当作是一种计算机科学的训练，而应该是“<ruby>程序性认识论<rt>procedural epistemology</rt></ruby>”的一种新表达方式 [^20]。程序是将那些偶然被送入计算机的思想组织起来的全新方法。这本书的第一章简明地介绍了 Lisp，但是之后的绝大部分都在讲述更加抽象的概念。其中包括了对不同编程范式的讨论，对于面向对象系统中“时间”和“一致性”的讨论；在书中的某一处，还有关于通信的基本限制可能会如何带来同步问题的讨论 —— 而这些基本限制在通信中就像是光速不变在相对中一样关键 [^21]。都是些高深难懂的东西。
|
||||
|
||||
以上这些并不是说这是本糟糕的书；这本书其实棒极了。在我读过的所有作品中，这本书对于重要的编程理念的讨论是最为深刻的；那些理念我琢磨了很久，却一直无力用文字去表达。一本入门编程教科书能如此迅速地开始描述面向对象编程的根本缺陷，和函数式语言“将可变状态降到最少”的优点，实在是一件让人印象深刻的事。而这种描述之后变为了另一种震撼人心的讨论：某种（可能类似于今日的 [RxJS][18] 的）流范式能如何同时具备两者的优秀特性。SICP 用和当初 McCarthy 的 Lisp 论文相似的方式提纯出了高级程序设计的精华。你读完这本书之后，会立即想要将它推荐给你的程序员朋友们；如果他们找到这本书，看到了封面，但最终没有阅读的话，他们就只会记住长着动物腿的桌子上方那神秘的、根本的、给予魔法师特殊能力的、写着 eval/apply 的东西。话说回来，书上这两人的鞋子也让我印象颇深。
|
||||
以上这些并不是说这是本糟糕的书；这本书其实棒极了。在我读过的所有作品中，这本书对于重要的编程理念的讨论是最为深刻的；那些理念我琢磨了很久，却一直无力用文字去表达。一本入门编程教科书能如此迅速地开始描述面向对象编程的根本缺陷，和函数式语言“将可变状态降到最少”的优点，实在是一件让人印象深刻的事。而这种描述之后变为了另一种震撼人心的讨论：某种（可能类似于今日的 [RxJS][18] 的）流范式能如何同时具备两者的优秀特性。SICP 用和当初麦卡锡的 Lisp 论文相似的方式提纯出了高级程序设计的精华。你读完这本书之后，会立即想要将它推荐给你的程序员朋友们；如果他们找到这本书，看到了封面，但最终没有阅读的话，他们就只会记住长着动物腿的桌子上方那神秘的、根本的、给予魔法师特殊能力的、写着 eval/apply 的东西。话说回来，书上这两人的鞋子也让我印象颇深。
|
||||
|
||||
然而，SICP 最重要的影响恐怕是，它将 Lisp 由一门怪语言提升成了必要教学工具。在 SICP 面世之前，人们互相推荐 Lisp，以学习这门语言为提升编程技巧的途径。1979 年的 Byte 杂志 Lisp 特刊印证了这一事实。之前提到的那位编辑不仅就麻省理工的新计算机大书特书，还说，Lisp 这门语言值得一学，因为它“代表了分析问题的另一种视角”。但 SICP 并未只把 Lisp 作为其它语言的陪衬来使用；SICP 将其作为入门语言。这就暗含了一种论点，那就是，Lisp 是最能把握计算机编程基础的语言。可以认为，如今的程序员们彼此怂恿“在死掉之前至少试试 Lisp”的时候，他们很大程度上是因为 SICP 才这么说的。毕竟，编程语言 [Brainfuck][19] 想必同样也提供了“分析问题的另一种视角”；但人们学习 Lisp 而非学习 Brainfuck，那是因为他们知道，前者的那种视角在二十年中都被看作是极其有用的，有用到麻省理工在给他们的本科生教其它语言之前，必然会先教 Lisp。
|
||||
然而，SICP 最重要的影响恐怕是，它将 Lisp 由一门怪语言提升成了必要的教学工具。在 SICP 面世之前，人们互相推荐 Lisp，以学习这门语言为提升编程技巧的途径。1979 年的 Byte 杂志 Lisp 特刊印证了这一事实。之前提到的那位编辑不仅就麻省理工的新 Lisp 计算机大书特书，还说，Lisp 这门语言值得一学，因为它“代表了分析问题的另一种视角” [^22]。但 SICP 并未只把 Lisp 作为其它语言的陪衬来使用；SICP 将其作为*入门*语言。这就暗含了一种论点，那就是，Lisp 是最能把握计算机编程基础的语言。可以认为，如今的程序员们彼此怂恿“在死掉之前至少试试 Lisp”的时候，他们很大程度上是因为 SICP 才这么说的。毕竟，编程语言 [Brainfuck][19] 想必同样也提供了“分析问题的另一种视角”；但人们学习 Lisp 而非学习 Brainfuck，那是因为他们知道，前者的那种 Lisp 视角在二十年中都被看作是极其有用的，有用到麻省理工在给他们的本科生教其它语言之前，必然会先教 Lisp。
|
||||
|
||||
### Lisp 的回归
|
||||
|
||||
在 SICP 出版的同一年，Bjarne Stroustrup 公布了 C++ 语言的首个版本，它将面向对象编程带到了大众面前。几年之后，Lisp 计算机市场崩盘，AI 寒冬开始了。在下一个十年的变革中， C++ 和后来的 Java 成了前途无量的语言，而 Lisp 被冷落，无人问津。
|
||||
在 SICP 出版的同一年，<ruby>本贾尼·斯特劳斯特卢普<rt>Bjarne Stroustrup</rt></ruby>发布了 C++ 语言的首个版本，它将面向对象编程带到了大众面前。几年之后，Lisp 计算机的市场崩盘，AI 寒冬开始了。在下一个十年的变革中， C++ 和后来的 Java 成了前途无量的语言，而 Lisp 被冷落，无人问津。
|
||||
|
||||
理所当然地，确定人们对 Lisp 重新燃起热情的具体时间并不可能；但这多半是 Paul Graham 发表他那几篇声称 Lisp 是首选入门语言的短文之后的事了。Paul Graham 是 Y-Combinator 的联合创始人和《黑客新闻》(Hacker News)的创始者，他这几篇短文有很大的影响力。例如，在短文[《胜于平庸》][20]（Beating the Averages）中，他声称 Lisp 宏使 Lisp 比其它语言更强。他说，因为他在自己创办的公司 Viaweb 中使用 Lisp，他得以比竞争对手更快地推出新功能。至少，[一部分程序员][21]被说服了。然而，庞大的主流程序员群体并未换用 Lisp。
|
||||
理所当然地，确定人们对 Lisp 重新燃起热情的具体时间并不可能；但这多半是保罗·格雷厄姆发表他那几篇声称 Lisp 是首选入门语言的短文之后的事了。保罗·格雷厄姆是 Y-Combinator 的联合创始人和《Hacker News》的创始者，他这几篇短文有很大的影响力。例如，在短文《<ruby>[胜于平庸][20]<rt>Beating the Averages</rt></ruby>》中，他声称 Lisp 宏使 Lisp 比其它语言更强。他说，因为他在自己创办的公司 Viaweb 中使用 Lisp，他得以比竞争对手更快地推出新功能。至少，[一部分程序员][21]被说服了。然而，庞大的主流程序员群体并未换用 Lisp。
|
||||
|
||||
实际上出现的情况是，Lisp 并未流行，但越来越多 Lisp 式的特性被加入到广受欢迎的语言中。Python 有了列表理解。C# 有了 Linq。Ruby……嗯，[Ruby 是 Lisp 的一种][22]。就如 Graham 在2002年提到的那样，“在一系列常用语言中所体现出的‘默认语言’正越发朝着 Lisp 的方向演化”。尽管其它语言变得越来越像 Lisp，Lisp 本身仍然保留了其作为“很少人了解但是大家都该学的神秘语言”的特殊声望。在 1980 年，Lisp 的诞生二十周年纪念日上，McCarthy写道，Lisp 之所以能够存活这么久，是因为它具备“编程语言领域中的某种近似局部最优”。这句话并未充分地表明 Lisp 的真正影响力。Lisp 能够存活超过半个世纪之久，并非因为程序员们一年年地勉强承认它就是最好的编程工具；事实上，即使绝大多数程序员根本不用它，它还是存活了下来。多亏了它的起源和它的人工智能研究用途，说不定还要多亏 SICP 的遗产，Lisp 一直都那么让人着迷。在我们能够想象上帝用其它新的编程语言创造世界之前，Lisp 都不会走下神坛。
|
||||
实际上出现的情况是，Lisp 并未流行，但越来越多 Lisp 式的特性被加入到广受欢迎的语言中。Python 有了列表理解。C# 有了 Linq。Ruby……嗯，[Ruby 是 Lisp 的一种][22]。就如格雷厄姆之前在 2001 年提到的那样，“在一系列常用语言中所体现出的‘默认语言’正越发朝着 Lisp 的方向演化” [^23]。尽管其它语言变得越来越像 Lisp，Lisp 本身仍然保留了其作为“很少人了解但是大家都该学的神秘语言”的特殊声望。在 1980 年，Lisp 的诞生二十周年纪念日上，麦卡锡写道，Lisp 之所以能够存活这么久，是因为它具备“编程语言领域中的某种近似局部最优” [^24]。这句话并未充分地表明 Lisp 的真正影响力。Lisp 能够存活超过半个世纪之久，并非因为程序员们一年年地勉强承认它就是最好的编程工具；事实上，即使绝大多数程序员根本不用它，它还是存活了下来。多亏了它的起源和它的人工智能研究用途，说不定还要多亏 SICP 的遗产，Lisp 一直都那么让人着迷。在我们能够想象上帝用其它新的编程语言创造世界之前，Lisp 都不会走下神坛。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
[^1]: John McCarthy, “History of Lisp”, 14, Stanford University, February 12, 1979, accessed October 14, 2018, http://jmc.stanford.edu/articles/lisp/lisp.pdf
|
||||
|
||||
[^2]: Paul Graham, “The Roots of Lisp”, 1, January 18, 2002, accessed October 14, 2018, http://languagelog.ldc.upenn.edu/myl/llog/jmc.pdf.
|
||||
|
||||
[^3]: Martin Childs, “John McCarthy: Computer scientist known as the father of AI”, The Independent, November 1, 2011, accessed on October 14, 2018, https://www.independent.co.uk/news/obituaries/john-mccarthy-computer-scientist-known-as-the-father-of-ai-6255307.html.
|
||||
|
||||
[^4]: Lisp Bulletin History. http://www.artinfo-musinfo.org/scans/lb/lb3f.pdf
|
||||
|
||||
[^5]: Allen Newell and Herbert Simon, “Current Developments in Complex Information Processing,” 19, May 1, 1956, accessed on October 14, 2018, http://bitsavers.org/pdf/rand/ipl/P-850_Current_Developments_In_Complex_Information_Processing_May56.pdf.
|
||||
|
||||
[^6]: ibid.
|
||||
|
||||
[^7]: Herbert Stoyan, “Lisp History”, 43, Lisp Bulletin #3, December 1979, accessed on October 14, 2018, http://www.artinfo-musinfo.org/scans/lb/lb3f.pdf
|
||||
|
||||
[^8]: McCarthy, “History of Lisp”, 5.
|
||||
|
||||
[^9]: ibid.
|
||||
|
||||
[^10]: McCarthy “History of Lisp”, 6.
|
||||
|
||||
[^11]: Stoyan, “Lisp History”, 45
|
||||
|
||||
[^12]: McCarthy, “History of Lisp”, 8.
|
||||
|
||||
[^13]: McCarthy, “History of Lisp”, 2.
|
||||
|
||||
[^14]: McCarthy, “History of Lisp”, 8.
|
||||
|
||||
[^15]: Graham, “The Roots of Lisp”, 11.
|
||||
|
||||
[^16]: Guy Steele and Richard Gabriel, “The Evolution of Lisp”, 22, History of Programming Languages 2, 1993, accessed on October 14, 2018, http://www.dreamsongs.com/Files/HOPL2-Uncut.pdf. 2
|
||||
|
||||
[^17]: Carl Helmers, “Editorial”, Byte Magazine, 154, August 1979, accessed on October 14, 2018, https://archive.org/details/byte-magazine-1979-08/page/n153.
|
||||
|
||||
[^18]: Patrick Winston, “The Lisp Revolution”, 209, April 1985, accessed on October 14, 2018, https://archive.org/details/byte-magazine-1985-04/page/n207.
|
||||
|
||||
[^19]: Harold Abelson, Gerald Jay. Sussman, and Julie Sussman, Structure and Interpretation of Computer Programs (Cambridge, Mass: MIT Press, 2010), xiii.
|
||||
|
||||
[^20]: Abelson, xxiii.
|
||||
|
||||
[^21]: Abelson, 428.
|
||||
|
||||
[^22]: Helmers, 7.
|
||||
|
||||
[^23]: Paul Graham, “What Made Lisp Different”, December 2001, accessed on October 14, 2018, http://www.paulgraham.com/diff.html.
|
||||
|
||||
[^24]: John McCarthy, “Lisp—Notes on its past and future”, 3, Stanford University, 1980, accessed on October 14, 2018, http://jmc.stanford.edu/articles/lisp20th/lisp20th.pdf.
|
||||
|
||||
via: https://twobithistory.org/2018/10/14/lisp.html
|
||||
|
||||
作者：[Two-Bit History][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[Northurland](https://github.com/Northurland)
|
||||
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 +1,82 @@
|
||||
监测数据库的健康和行为: 有哪些重要指标？
|
||||
======
|
||||
对数据库的监测可能过于困难或者没有监测到关键点。本文将讲述如何正确的监测数据库。
|
||||
|
||||
|
||||
我们没有足够的讨论数据库。在这个充满监测仪器的时代，我们监测我们的应用程序、基础设施、甚至我们的用户，但有时忘记我们的数据库也值得被监测。这很大程度是因为数据库表现的很好，以至于我们单纯地信任它能把任务完成的很好。信任固然重要，但能够证明它的表现确实如我们所期待的那样就更好了。
|
||||
|
||||
|
||||
|
||||
### 为什么监测你的数据库？
|
||||
|
||||
监测数据库的原因有很多，其中大多数原因与监测系统的任何其他部分的原因相同：了解应用程序的各个组件中发生的什么，会让你成为更了解情况的，能够做出明智决策的开发人员。
|
||||
|
||||
|
||||
|
||||
更具体地说,数据库是系统健康和行为的重要标志。数据库中的异常行为能够指出应用程序中出现问题的区域。另外，当应用程序中有异常行为时，你可以利用数据库的指标来迅速完成排除故障的过程。
|
||||
|
||||
### 问题
|
||||
|
||||
最轻微的调查揭示了监测数据库的一个问题：数据库有很多指标。说“很多”只是轻描淡写，如果你是Scrooge McDuck，你可以浏览所有可用的指标。如果这是Wrestlemania，那么指标就是折叠椅。监测所有指标似乎并不实用，那么你如何决定要监测哪些指标？
|
||||
|
||||
|
||||
|
||||
### 解决方案
|
||||
|
||||
开始监测数据库的最好方式是认识一些基础的数据库指标。这些指标为理解数据库的行为创造了良好的开端。
|
||||
|
||||
### 吞吐量：数据库做了多少？
|
||||
|
||||
开始检测数据库的最好方法是跟踪它所接到请求的数量。我们对数据库有较高期望；期望它能稳定的存储数据，并处理我们抛给它的所有查询，这些查询可能是一天一次大规模查询，或者是来自用户一天到晚的数百万次查询。吞吐量可以告诉我们数据库是否如我们期望的那样工作。
|
||||
|
||||
你也可以将请求安照类型（读，写，服务器端，客户端等）分组，以开始分析流量。
|
||||
|
||||
### 执行时间：数据库完成工作需要多长时间？
|
||||
|
||||
这个指标看起来很明显，但往往被忽视了。 你不仅想知道数据库收到了多少请求，还想知道数据库在每个请求上花费了多长时间。 然而，参考上下文来讨论执行时间非常重要：像InfluxDB这样的时间序列数据库中的慢与像MySQL这样的关系型数据库中的慢不一样。InfluxDB中的慢可能意味着毫秒，而MySQL的“SLOW_QUERY”变量的默认值是10秒。
|
||||
|
||||
|
||||
|
||||
监测执行时间和提高执行时间不一样，所以如果你的应用程序中有其他问题需要修复，那么请注意在优化上花费时间的诱惑。
|
||||
|
||||
### 并发性：数据库同时做了多少工作？
|
||||
|
||||
一旦你知道数据库正在处理多少请求以及每个请求需要多长时间，你就需要添加一层复杂性以开始从这些指标中获得实际值。
|
||||
|
||||
如果数据库接收到十个请求，并且每个请求需要十秒钟来完成，那么数据库是否忙碌了100秒、10秒，或者介于两者之间？并发任务的数量改变了数据库资源的使用方式。当你考虑连接和线程的数量等问题时，你将开始对数据库指标有更全面的了解。
|
||||
|
||||
并发性还能影响延迟，这不仅包括任务完成所需的时间（执行时间），还包括任务在处理之前需要等待的时间。
|
||||
|
||||
### 利用率：数据库繁忙的时间百分比是多少？
|
||||
|
||||
利用率是由吞吐量、执行时间和并发性的峰值所确定的数据库可用的频率，或者数据库太忙而不能响应请求的频率。
|
||||
|
||||
|
||||
|
||||
该指标对于确定数据库的整体健康和性能特别有用。如果只能在80%的时间内响应请求，则可以重新分配资源、进行优化工作，或者进行更改以更接近高可用性。
|
||||
|
||||
### 好消息
|
||||
|
||||
监测和分析似乎非常困难，特别是因为我们大多数人不是数据库专家，我们可能没有时间去理解这些指标。但好消息是，大部分的工作已经为我们做好了。许多数据库都有一个内部性能数据库（Postgres：pg_stats、CouchDB：Runtime_.、InfluxDB：_internal等），数据库工程师设计该数据库来监测与该特定数据库有关的指标。你可以看到像慢速查询的数量一样广泛的内容，或者像数据库中每个事件的平均微秒一样详细的内容。
|
||||
|
||||
### 结论
|
||||
|
||||
数据库创建了足够的指标以使我们需要长时间研究，虽然内部性能数据库充满了有用的信息，但并不总是使你清楚应该关注哪些指标。 从吞吐量，执行时间，并发性和利用率开始，它们为你提供了足够的信息，使你可以开始了解你的数据库中的情况。
|
||||
|
||||
|
||||
|
||||
你在监视你的数据库吗？你发现哪些指标有用？告诉我吧！
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/10/database-metrics-matter
|
||||
|
||||
作者：[Katy Farmer][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[ChiZelin](https://github.com/ChiZelin)
|
||||
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/thekatertot
|
||||
[b]: https://github.com/lujun9972
|
||||
@ -0,0 +1,213 @@
|
||||
如何在 Linux 上对驱动器进行分区和格式化
|
||||
======
|
||||
这里有所有你想知道的关于设置存储器而又不敢问的一切。
|
||||
|
||||
|
||||
|
||||
在大多数的计算机系统上，Linux 或者是其它，当你插入一个 USB 设备时，你会注意到一个提示驱动器存在的警告。如果该驱动器已经按你想要的进行分区和格式化，你只需要你的计算机在文件管理器或桌面上的某个地方列出驱动器。这是一个简单的要求，而且通常计算机都能满足。
|
||||
|
||||
然而，有时候，驱动器并没有按你想要的方式进行格式化。对于这些，你必须知道如何查找准备连接到您计算机上的存储设备。
|
||||
|
||||
### 什么是块设备？
|
||||
|
||||
硬盘驱动器通常被称为“块设备”，因为硬盘驱动器以固定大小的块进行读写。这就可以区分硬盘驱动器和其它可能插入到您计算机的一些设备，如打印机，游戏手柄，麦克风，或相机。一个简单的方法用来列出连接到你 Linux 系统上的块设备就是使用 `lsblk` （list block devices）命令：
|
||||
|
||||
```
|
||||
$ lsblk
|
||||
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
|
||||
sda 8:0 0 238.5G 0 disk
|
||||
├─sda1 8:1 0 1G 0 part /boot
|
||||
└─sda2 8:2 0 237.5G 0 part
|
||||
└─luks-e2bb...e9f8 253:0 0 237.5G 0 crypt
|
||||
├─fedora-root 253:1 0 50G 0 lvm /
|
||||
├─fedora-swap 253:2 0 5.8G 0 lvm [SWAP]
|
||||
└─fedora-home 253:3 0 181.7G 0 lvm /home
|
||||
sdb 8:16 1 14.6G 0 disk
|
||||
└─sdb1 8:17 1 14.6G 0 part
|
||||
```
|
||||
|
||||
最左列是设备标识符，每个都是以 `sd` 开头，并以一个字母结尾，字母从 `a` 开始。每个块设备上的分区分配一个数字，从 1 开始。例如，第一个设备上的第二个分区用 `sda2` 表示。如果你不确定到底是哪个分区，那也不要紧，只需接着往下读。
|
||||
|
||||
`lsblk` 命令是无损的，仅仅用于检测，所以你可以放心的使用而不用担心破坏你驱动器上的数据。
|
||||
|
||||
### 使用 `dmesg` 进行测试
|
||||
|
||||
如果你有疑问，你可以通过在 `dmesg` 命令的最后几行查看驱动器的卷标，这个命令显示了操作系统最近的日志（比如说插入或移除一个驱动器）。一句话，如果你想确认你插入的设备是不是 `/dev/sdc` ，那么，把设备插到你的计算机上，然后运行这个 `dmesg` 命令：
|
||||
|
||||
```
|
||||
$ sudo dmesg | tail
|
||||
```
|
||||
|
||||
显示中列出的最新的驱动器就是你刚刚插入的那个。如果你拔掉它，并再运行这个命令一次，你可以看到，这个设备已经被移除。如果你再插上它再运行命令，这个设备又会出现在那里。换句话说，你可以监控内核对驱动器的识别。
|
||||
|
||||
### 解理文件系统
|
||||
|
||||
如果你只需要设备卷标，那么你的工作就完成了。但是如果你的目的是想创建一个可用的驱动器，那你还必须给这个驱动器做一个文件系统。
|
||||
|
||||
如果你还不知道什么是文件系统，那么通过了解当没有文件系统时会发生什么，可能会更容易理解这个概念。如果你有多余的设备驱动器，并且上面没有什么重要的数据资料，你可以跟着做一下下面的这个实验。否则，请不要尝试，因为根据设计，这个肯定会删除您的资料。
|
||||
|
||||
当一个驱动器没有文件系统时也是可以使用的。一旦你已经肯定，正解识别了一个驱动器，并且已经确定上面没有任何重要的资料，那就可以把它插到你的计算机上——但是不要挂载它，如果它被自动挂载上了，那就请手动卸载掉它。
|
||||
|
||||
```
|
||||
$ su -
|
||||
# umount /dev/sdx{,1}
|
||||
```
|
||||
|
||||
为了防止灾难性的复制-粘贴错误，下面的例子将使用不太可能出现的 `sdx` 来作为驱动器的卷标。
|
||||
|
||||
现在，这个驱动器已经被卸载了，尝试使用下面的命令：
|
||||
|
||||
```
|
||||
# echo 'hello world' > /dev/sdx
|
||||
```
|
||||
|
||||
你已经可以将数据写入到块设备中，而无需将其挂载到你的操作系统上，也不需要一个文件系统。
|
||||
|
||||
再把刚写入的数据取出来，你可以看到驱动器上的原始数据：
|
||||
|
||||
```
|
||||
# head -n 1 /dev/sdx
|
||||
hello world
|
||||
```
|
||||
|
||||
这看起来工作得很好，但是想象一下如果 "hello world" 这个短语是一个文件，如果你想要用这种方法写入一个新的文件，则必须：
|
||||
|
||||
1. 知道第 1 行已经存在一个文件了
|
||||
2. 知道已经存在的文件只占用了 1 行
|
||||
3. 创建一种新的方法来在后面添加数据，或者在写第 2 行的时候重写第 1 行
|
||||
|
||||
例如：
|
||||
|
||||
```
|
||||
# echo 'hello world
|
||||
> this is a second file' >> /dev/sdx
|
||||
```
|
||||
|
||||
获取第 1 个文件，没有任何改变。
|
||||
|
||||
```
|
||||
# head -n 1 /dev/sdx
|
||||
hello world
|
||||
```
|
||||
|
||||
但是，获取第 2 个文件的时候就显得有点复杂了。
|
||||
|
||||
```
|
||||
# head -n 2 /dev/sdx | tail -n 1
|
||||
this is a second file
|
||||
```
|
||||
|
||||
显然，通过这种方式读写数据并不实用，因此，开发人员创建了一个系统来跟踪文件的组成，并标识一个文件的开始和结束，等等。
|
||||
|
||||
大多数的文件系统都需要一个分区。
|
||||
|
||||
### 创建分区
|
||||
|
||||
分区是硬盘驱动器的一种边界，用来告诉文件系统它可以占用哪些空间。举例来说，你有一个 4GB 的 USB 驱动器，你可以只分一个分区占用一个驱动器 （4GB），或两个分区，每个 2GB (又或者是一个 1GB，一个 3GB，只要你愿意)，或者三个不同的尺寸大小，等等。这种组合将是无穷无尽的。
|
||||
|
||||
假设你的驱动器是 4GB，你可以 GNU `parted` 命令来创建一个大的分区。
|
||||
|
||||
```
|
||||
# parted /dev/sdx --align opt mklabel msdos 0 4G
|
||||
```
|
||||
|
||||
按 `parted` 命令的要求，首先指定了驱动器的路径。
|
||||
|
||||
`\--align` 选项让 `parted` 命令自动选择一个最佳的开始点和结束点。
|
||||
|
||||
`mklabel` 命令在驱动器上创建了一个分区表 （称为磁盘卷标）。这个例子使用了 msdos 磁盘卷标，因为它是一个非常兼容和流行的卷标，虽然 gpt 正变得越来越普遍。
|
||||
|
||||
最后定义了分区所需的起点和终点。因为使用了 `\--align opt` 标志，所以 `parted` 将根据需要调整大小以优化驱动器的性能，但这些数字仍然可以做为参考。
|
||||
|
||||
接下来，创建实际的分区。如果你开始点和结束点的选择并不是最优的， `parted` 会向您发出警告并让您做出调整。
|
||||
|
||||
```
|
||||
# parted /dev/sdx -a opt mkpart primary 0 4G
|
||||
|
||||
Warning: The resulting partition is not properly aligned for best performance: 1s % 2048s != 0s
|
||||
Ignore/Cancel? C
|
||||
# parted /dev/sdx -a opt mkpart primary 2048s 4G
|
||||
```
|
||||
|
||||
如果你再次运行 `lsblk` 命令，（你可能必须要拔掉驱动器，并把它再插回去），你就可以看到你的驱动器上现在已经有一个分区了。
|
||||
|
||||
### 手动创建一个文件系统
|
||||
|
||||
我们有很多文件系统可以使用。有些是开源和免费的，另外的一些并不是。一些公司拒绝支持开源文件系统，所以他们的用户无法使用开源的文件系统读取，而开源的用户也无法在不对其进行逆向工程的情况下从封闭的文件系统中读取。
|
||||
|
||||
尽管有这种特殊的情况存在，还是仍然有很多操作系统可以使用，选择哪个取决于驱动器的用途。如果你希望你的驱动器兼容多个系统，那么你唯一的选择是 exFAT 文件系统。然而微软尚未向任何开源内核提交 exFAT 的代码，因此你可能必须在软件包管理器中安装 exFAT 支持，但是 Windows 和 MacOS 都支持 exFAT 文件系统。
|
||||
|
||||
一旦你安装了 exFAT 支持，你可以在驱动器上你创建好的分区中创建一个 exFAT 文件系统。
|
||||
|
||||
```
|
||||
# mkfs.exfat -n myExFatDrive /dev/sdx1
|
||||
```
|
||||
|
||||
现在你的驱动器可由封闭系统和其它开源的系统（尚未经过微软批准）内核模块进行读写了。
|
||||
|
||||
Linux 中常见的文件系统是 [ext4][1]。但对于便携式的设备来说，这可能是一个麻烦的文件系统，因为它保留了用户的权限，这些权限通常因为计算机而异，但是它通常是一个可靠而灵活的文件系统。只要你熟悉管理权限，那 ext4 对于便携式的设备来说就是一个很棒的文件系统。
|
||||
|
||||
```
|
||||
# mkfs.ext4 -L myExt4Drive /dev/sdx1
|
||||
```
|
||||
|
||||
拔掉你的驱动器，再把它插回去。对于 ext4 文件系统的便携设备来说，使用 `sudo` 创建一个目录，并将该目录的权限授予用户和系统中通用的组。如果你不确定使用哪个用户和组，也可以使用 `sudo` 或 `root` 来修改出现问题的设备的读写权限。
|
||||
|
||||
### 使用桌面工具
|
||||
|
||||
很高兴知道了在只有一个 Linux shell的时候，如何操作和处理你的块设备，但是，有时候你仅仅是想让一个驱动器可用，而不需要进行那么多的检测。 GNOME 的 KDE 的开发者们提供了这样的一些优秀的工具让这个过程变得简单。
|
||||
|
||||
[GNOME 磁盘][2] 和 [KDE 分区管理器][3] 是一个图形化的工具，为本文到目前为止提到的一切提供了一个一体化的解决方案。启动其中的任何一个，来查看所有连接的设备（在左侧列表中），创建和调整分区大小，和创建文件系统。
|
||||
|
||||
![KDE 分区管理器][5]
|
||||
|
||||
KDE 分区管理器
|
||||
|
||||
可以预见的是，GNOME 版本会比 KDE 版本更加简单，因此，我将使用复杂的版本进行演示——如果你愿意动手的话，很容易弄清楚 GNOME 磁盘工具的使用。
|
||||
|
||||
启动 KDE 分区管理工具，然后输入你的 root 密码。
|
||||
|
||||
在最左边的一列，选择你想要格式化的驱动器。如果你的驱动器并没有列出来，确认下是否已经插好，然后选择 Tools > Refresh devices （或使用键盘上的 F5 键）。
|
||||
|
||||
除非你想销毁驱动器已经存在的分区表，否则请勿继续。选择好驱动器后，单击顶部工具栏中的 New Partition Table 。系统会提示你为该分区选择一个卷标： gpt 或 msdos 。前者更加灵活可以处理更大的驱动器，而后者像很多微软的技术一样，是占据大量市场份额的事实上的标准。
|
||||
|
||||
现在您有了一个新的分区表，在右侧的面板中右键单击你的设备，然后选择 New 来创建新的分区，按照提示设置分区的类型和大小。此操作包括了分区步骤和创建文件系统。
|
||||
|
||||
![创建一个新分区][7]
|
||||
|
||||
创建一个新分区
|
||||
|
||||
要将更改应用于你的驱动器，单击窗口左上角的 Apply 按钮。
|
||||
|
||||
### 硬盘驱动器， 容易驱动
|
||||
|
||||
在 Linux 上处理硬盘驱动器很容易，甚至如果你理解硬盘驱动器的语言就更容易了。自从切换到 Linux 系统以来，我已经能够以任何我想要的方式来处理我的硬盘驱动器了。由于 Linux 在处理存储提供的透明性，因此恢复数据也变得更加容易了。
|
||||
|
||||
如果你想实验并了解有关硬盘驱动器的更多的信息，请参考下面的几个提示：
|
||||
|
||||
1. 备份您的数据，而不仅仅是你在实验的驱动器上。仅仅需要一个小小的错误操作来破坏一个重要驱动器的分区。（这是一个用来学习重建丢失分区的很好的方法，但并不是很有趣）。
|
||||
2. 反复确认你所定位的驱动器是正确的驱动器。我经常使用 `lsblk` 来确定我并没有移动驱动器。（因为从两个独立的 USB 端口移除两个驱动器很容易，然后以不同的顺序重新连接它们，就会很容易导致它们获得了新的驱动器标签。）
|
||||
3. 花点时间“销毁”你测试的驱动器，看看你是否可以把数据恢复。在删除文件系统后，重新创建分区表或尝试恢复数据是一个很好的学习体验。
|
||||
|
||||
还有一些更好玩的东西，如果你身边有一个封闭的操作系统，在上面尝试使用一个开源的文件系统。有一些项目致力于解决这种兼容性，并且尝试让它们以一种可靠稳定的方式工作是一个很好的业余项目。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/18/11/partition-format-drive-linux
|
||||
|
||||
作者：[Seth Kenlon][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[Jamskr](https://github.com/Jamskr)
|
||||
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
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/article/17/5/introduction-ext4-filesystem
|
||||
[2]: https://wiki.gnome.org/Apps/Disks
|
||||
[3]: https://www.kde.org/applications/system/kdepartitionmanager/
|
||||
[4]: /file/413586
|
||||
[5]: https://opensource.com/sites/default/files/uploads/blockdevices_kdepartition.jpeg (KDE Partition Manager)
|
||||
[6]: /file/413591
|
||||
[7]: https://opensource.com/sites/default/files/uploads/blockdevices_newpartition.jpeg (Create a new partition)
|
||||
121
translated/tech/20181107 Automate a web browser with Selenium.md
Normal file
121
translated/tech/20181107 Automate a web browser with Selenium.md
Normal file
@ -0,0 +1,121 @@
|
||||
使用 Selenium 自动化 Web 浏览器
|
||||
======
|
||||
|
||||
|
||||
[Selenium][1] 是浏览器自动化的绝佳工具。使用 Selenium IDE，你可以录制命令序列（如单击、拖动和输入），验证结果并最终存储此自动化测试供日后使用。这非常适合在浏览器中进行积极开发。但是当你想要将这些测试与 CI/CD 流集成时，是时候使用 Selenium WebDriver 了。
|
||||
|
||||
WebDriver 公开了一个绑定了许多编程语言的 API，它允许你将浏览器测试与其他测试集成。这篇文章向你展示了如何在容器中运行 WebDriver 并将其与 Python 程序一起使用。
|
||||
|
||||
### 使用 Podman 运行 Selenium
|
||||
|
||||
Podman是下面例子的容器运行时。有关如何开始使用 Podman 的信息，请参见[此前文章][2]。
|
||||
|
||||
此例使用了 Selenium 的独立容器，其中包含 WebDriver 服务器和浏览器本身。要在后台启动服务器容器，请运行以下命令：
|
||||
|
||||
```
|
||||
$ podman run -d --network host --privileged --name server \
|
||||
docker.io/selenium/standalone-firefox
|
||||
```
|
||||
|
||||
当你使用特权标志和主机网络运行容器时，你可以稍后从在 Python 中连接到此容器。你不需要使用 sudo。
|
||||
|
||||
### 在 Python 中使用 Selenium
|
||||
|
||||
现在你可以提供一个使用此服务器的简单程序。这个程序很小，但应该会让你知道可以做什么：
|
||||
|
||||
```
|
||||
from selenium import webdriver
|
||||
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
|
||||
|
||||
server ="http://127.0.0.1:4444/wd/hub"
|
||||
|
||||
driver = webdriver.Remote(command_executor=server,
|
||||
desired_capabilities=DesiredCapabilities.FIREFOX)
|
||||
|
||||
print("Loading page...")
|
||||
driver.get("https://fedoramagazine.org/")
|
||||
print("Loaded")
|
||||
assert "Fedora" in driver.title
|
||||
|
||||
driver.quit()
|
||||
print("Done.")
|
||||
```
|
||||
|
||||
首先，程序连接到你已经启动的容器。然后它加载 Fedora Magazine 网页并判断 “Fedora” 是页面标题的一部分。最后，它退出会话。
|
||||
|
||||
需要 Python 绑定才能运行此程序。既然你已经在使用容器了，为什么不在容器中这样做呢？将以下内容保存到 Dockerfile 中：
|
||||
|
||||
```
|
||||
FROM fedora:29
|
||||
RUN dnf -y install python3
|
||||
RUN pip3 install selenium
|
||||
```
|
||||
|
||||
然后使用 Podman 在与 Dockerfile 相同的文件夹中构建容器镜像：
|
||||
|
||||
```
|
||||
$ podman build -t selenium-python .
|
||||
```
|
||||
|
||||
要在容器中运行程序，在运行容器时将包含 Python 代码的文件作为卷挂载：
|
||||
|
||||
```
|
||||
$ podman run -t --rm --network host \
|
||||
-v $(pwd)/browser-test.py:/browser-test.py:z \
|
||||
selenium-python python3 browser-test.py
|
||||
```
|
||||
|
||||
输出看上去像这样：
|
||||
|
||||
```
|
||||
Loading page...
|
||||
Loaded
|
||||
Done.
|
||||
```
|
||||
|
||||
### 接下来做什么
|
||||
|
||||
上面的示例程序是最小的，也许没那么有用。但这仅仅是最表面的东西！查看 [Selenium][3] 和 [Python 绑定][4] 的文档。在那里，你将找到有关如何在页面中查找元素、处理弹出窗口或填写表单的示例。拖放也是可能的，当然还有等待事件。
|
||||
|
||||
在实现一些不错的测试后，你可能希望将它们包含在 CI/CD pipeline 中。幸运的是，这是相当直接的，因为一切都是容器化的。
|
||||
|
||||
你可能也有兴趣设置 [grid][5] 来并行运行测试。这不仅有助于加快速度，还允许你同时测试多个不同的浏览器。
|
||||
|
||||
### 清理
|
||||
|
||||
当你容器使用完后，可以使用以下命令停止并删除独立容器：
|
||||
|
||||
```
|
||||
$ podman stop server
|
||||
$ podman rm server
|
||||
```
|
||||
|
||||
如果你还想释放磁盘空间，请运行以下命令删除镜像：
|
||||
|
||||
```
|
||||
$ podman rmi docker.io/selenium/standalone-firefox
|
||||
$ podman rmi selenium-python fedora:29
|
||||
```
|
||||
|
||||
### 总结
|
||||
|
||||
在本篇中，你已经看到使用容器技术开始使用 Selenium 是多么容易。它允许你自动化与网站的交互，以及测试交互。Podman 允许你在没有超级用户权限或 Docker 守护程序的情况下运行所需的容器。最后，Python 绑定允许你使用普通的 Python 代码与浏览器进行交互。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://fedoramagazine.org/automate-web-browser-selenium/
|
||||
|
||||
作者：[Lennart Jern][a]
|
||||
选题：[lujun9972][b]
|
||||
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://fedoramagazine.org/author/lennartj/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.seleniumhq.org/
|
||||
[2]: https://fedoramagazine.org/running-containers-with-podman/
|
||||
[3]: https://www.seleniumhq.org/docs/
|
||||
[4]: https://selenium-python.readthedocs.io
|
||||
[5]: https://www.seleniumhq.org/docs/07_selenium_grid.jsp
|
||||
@ -0,0 +1,185 @@
|
||||
在linux中如何查找一个命令或进程的执行时间
|
||||
======
|
||||
|
||||
|
||||
你可能知道一个命令或进程开始执行的时间和在类Unix系统中[**一个命令运行了多久**][1]。 但是，你如何知道这个命令或进程何时结束或者它完成运行所花费的总时间呢？ 在类Unix系统中,这是非常容易的! 有一个程序专门为此设计名叫 **‘GNU time’**。 使用time程序, 我们可以轻松地测量Linux操作系统中命令或程序的总执行时间。 ‘time’命令在大多数Linux发行版中都有预装, 所以你不必去安装它。
|
||||
|
||||
### 在Linux中查找一个命令或进程的执行时间
|
||||
|
||||
要测量一个命令或程序的执行时间，运行。
|
||||
|
||||
```
|
||||
$ /usr/bin/time -p ls
|
||||
```
|
||||
|
||||
或者,
|
||||
|
||||
```
|
||||
$ time ls
|
||||
```
|
||||
|
||||
输出样例:
|
||||
|
||||
```
|
||||
dir1 dir2 file1 file2 mcelog
|
||||
|
||||
real 0m0.007s
|
||||
user 0m0.001s
|
||||
sys 0m0.004s
|
||||
|
||||
$ time ls -a
|
||||
. .bash_logout dir1 file2 mcelog .sudo_as_admin_successful
|
||||
.. .bashrc dir2 .gnupg .profile .wget-hsts
|
||||
.bash_history .cache file1 .local .stack
|
||||
|
||||
real 0m0.008s
|
||||
user 0m0.001s
|
||||
sys 0m0.005s
|
||||
```
|
||||
|
||||
以上命令显示出了 **‘ls’** 命令的总执行时间。 你可以将 “ls” 替换为任何命令或进程，以查找总的执行时间。
|
||||
|
||||
输出详解：
|
||||
|
||||
1. **real** -指的是命令或程序所花费的总时间
|
||||
2. **user** – 指的是在用户模式下程序所花费的时间,
|
||||
3. **sys** – 指的是在内核模式下程序所花费的时间。
|
||||
|
||||
|
||||
|
||||
我们也可以将命令限制为仅运行一段时间。
|
||||
|
||||
### time vs /usr/bin/time
|
||||
|
||||
你可能注意到了, 我们在上面的例子中使用了两个命令 **‘time’** and **‘/usr/bin/time’** 。 所以，你可能会想知道他们的不同。
|
||||
|
||||
首先， 让我们使用 ‘type’ 命令看看 ‘time’ 命令到底是什么。对于那些我们不知道的Linux命令, **Type** 命令用于查找相关命令的信息。 更多详细信息, [**请参阅本指南**][2]。
|
||||
|
||||
```
|
||||
$ type -a time
|
||||
time is a shell keyword
|
||||
time is /usr/bin/time
|
||||
```
|
||||
|
||||
正如你在上面的输出中看到的一样, 这两个都是time,
|
||||
|
||||
* 一个是BASH shell中内建的关键字
|
||||
* 一个是可执行文件 如 **/usr/bin/time**
|
||||
|
||||
|
||||
|
||||
由于shell关键字的优先级高于可执行文件, 当你没有给出完整路径只运行`time`命令时, 你运行的是shell内建的命令。 但是，当你运行 `/usr/bin/time`时, 你运行的是真正的 **GNU time** 命令。 因此，为了执行真正的命令你可能需要给出完整路径。
|
||||
|
||||
在大多数shell中如 BASH, ZSH, CSH, KSH, TCSH 等，内建的关键字‘time’是可用的。 ‘time’ 关键字的选项少于可执行文件. 你可以使用的唯一选项是 **-p**。
|
||||
|
||||
你现在知道如何使用 ‘time’ 命令查找给定命令或进程的总执行时间。 想进一步了解 ‘GNU time’ 工具吗？ 继续阅读吧！
|
||||
|
||||
### 关于 ‘GNU time’ 程序的简要介绍
|
||||
|
||||
Gnu time程序运行带有给定参数的命令或程序，并在命令完成后将系统资源使用情况汇总到标准输出。 与 ‘time’ 关键字不同, Gnu time程序不仅显示命令或进程的执行时间，还显示内存，I/O和IPC调用等其他资源。
|
||||
|
||||
time 命令的语法是：
|
||||
|
||||
```
|
||||
/usr/bin/time [options] command [arguments...]
|
||||
```
|
||||
|
||||
语法中的‘options’是指一组可以与time命令一起使用去执行特定功能的选项。 下面给出了可用的‘options’。
|
||||
|
||||
* **-f, –format** – 使用此选项可以根据需求指定输出格式。
|
||||
* **-p, –portability** – 使用简要的输出格式。
|
||||
* **-o file, –output=FILE** – 将输出写到指定文件中而不是到标准输出。
|
||||
* **-a, –append** – 将输出追加到文件中而不是覆盖它。
|
||||
* **-v, –verbose** – 此选项显示 ‘time’ 命令输出的详细信息。
|
||||
* **–quiet** – 此选项可以防止 ‘time’ 命令报告程序的状态.
|
||||
|
||||
|
||||
|
||||
当不带任何选项使用 ‘GNU time’ 命令时, 你将看到以下输出。
|
||||
|
||||
```
|
||||
$ /usr/bin/time wc /etc/hosts
|
||||
9 28 273 /etc/hosts
|
||||
0.00user 0.00system 0:00.00elapsed 66%CPU (0avgtext+0avgdata 2024maxresident)k
|
||||
0inputs+0outputs (0major+73minor)pagefaults 0swaps
|
||||
```
|
||||
|
||||
如果你用shell关键字 ‘time’ 运行相同的命令, 输出会有一点儿不同：
|
||||
|
||||
```
|
||||
$ time wc /etc/hosts
|
||||
9 28 273 /etc/hosts
|
||||
|
||||
real 0m0.006s
|
||||
user 0m0.001s
|
||||
sys 0m0.004s
|
||||
```
|
||||
|
||||
有时，你可能希望将系统资源使用情况输出到文件中而不是终端上。 为此, 你可以使用 **-o** 选项，如下所示。
|
||||
|
||||
```
|
||||
$ /usr/bin/time -o file.txt ls
|
||||
dir1 dir2 file1 file2 file.txt mcelog
|
||||
```
|
||||
|
||||
正如你看到的, time命令不会显示到终端上. 因为我们将输出写到了file.txt的文件中。 让我们看一下这个文件的内容：
|
||||
|
||||
```
|
||||
$ cat file.txt
|
||||
0.00user 0.00system 0:00.00elapsed 66%CPU (0avgtext+0avgdata 2512maxresident)k
|
||||
0inputs+0outputs (0major+106minor)pagefaults 0swaps
|
||||
```
|
||||
|
||||
当你使用 **-o** 选项时, 如果你没有一个文件名叫 ‘file.txt’, 它会创建一个并把输出写进去。 如果文件存在, 它会覆盖文件原来的内容。
|
||||
|
||||
你可以使用 **-a** 选项将输出追加到文件后面，而不是覆盖它的内容。
|
||||
|
||||
```
|
||||
$ /usr/bin/time -a file.txt ls
|
||||
```
|
||||
|
||||
**-f** 选项允许用户根据自己的喜好控制输出格式。 比如说, 以下命令的输出仅显示用户，系统和总时间。
|
||||
|
||||
```
|
||||
$ /usr/bin/time -f "\t%E real,\t%U user,\t%S sys" ls
|
||||
dir1 dir2 file1 file2 mcelog
|
||||
0:00.00 real, 0.00 user, 0.00 sys
|
||||
```
|
||||
|
||||
请注意shell中内建的 ‘time’ 命令并不具有Gnu time程序的所有功能。
|
||||
|
||||
有关Gnu time程序的详细说明可以使用man命令来查看。
|
||||
|
||||
```
|
||||
$ man time
|
||||
```
|
||||
|
||||
想要了解有关Bash 内建 ‘Time’ 关键字的更多信息, 请运行：
|
||||
|
||||
```
|
||||
$ help time
|
||||
```
|
||||
|
||||
就到这里吧。 希望对你有所帮助。
|
||||
|
||||
会有更多好东西分享哦。 请关注我们！
|
||||
|
||||
加油哦！
|
||||
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.ostechnix.com/how-to-find-the-execution-time-of-a-command-or-process-in-linux/
|
||||
|
||||
作者：[SK][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[caixiangyue](https://github.com/caixiangyue)
|
||||
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/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.ostechnix.com/find-long-process-running-linux/
|
||||
[2]: https://www.ostechnix.com/the-type-command-tutorial-with-examples-for-beginners/
|
||||
Loading…
Reference in New Issue
Block a user