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[#]: collector: (lujun9972)
[#]: translator: (geekpi)
[#]: reviewer: ( )
[#]: publisher: ( )
[#]: url: ( )
[#]: subject: (Command line quick tips: Locate and process files with find and xargs)
[#]: via: (https://fedoramagazine.org/command-line-quick-tips-locate-and-process-files-with-find-and-xargs/)
[#]: author: (Ben Cotton https://fedoramagazine.org/author/bcotton/)
Command line quick tips: Locate and process files with find and xargs
======
![][1]
**find** is one of the more powerful and flexible command-line programs in the daily toolbox. It does what the name suggests: it finds files and directories that match the conditions you specify. And with arguments like **-exec** or **-delete**, you can have find take action on what it… finds.
In this installment of the [Command Line Quick Tips][2] series, you’ll get an introduction to the **find** command and learn how to use it to process files with built-in commands or the **xargs** command.
### Finding files
At a minimum, **find** takes a path to find things in. For example, this command will find (and print) every file on the system:
```
find /
```
And since everything is a file, you will get a lot of output to sort through. This probably doesn’t help you locate what you’re looking for. You can change the path argument to narrow things down a bit, but it’s still not really any more helpful than using the **ls** command. So you need to think about what you’re trying to locate.
Perhaps you want to find all the JPEG files in your home directory. The **-name** argument allows you to restrict your results to files that match the given pattern.
```
find ~ -name '*jpg'
```
But wait! What if some of them have an uppercase extension? **-iname** is like **-name**, but it is case-insensitive:
```
find ~ -iname '*jpg'
```
Great! But the 8.3 name scheme is so 1985. Some of the pictures might have a .jpeg extension. Fortunately, we can combine patterns with an “or,” represented by **-o**. The parentheses are escaped so that the shell doesn’t try to interpret them instead of the **find** command.
```
find ~ \( -iname 'jpeg' -o -iname 'jpg' \)
```
We’re getting closer. But what if you have some directories that end in jpg? (Why you named a directory **bucketofjpg** instead of **pictures** is beyond me.) We can modify our command with the **-type** argument to look only for files:
```
find ~ \( -iname '*jpeg' -o -iname '*jpg' \) -type f
```
Or maybe you’d like to find those oddly named directories so you can rename them later:
```
find ~ \( -iname '*jpeg' -o -iname '*jpg' \) -type d
```
It turns out you’ve been taking a lot of pictures lately, so narrow this down to files that have changed in the last week with **-mtime** (modification time). The **-7** means all files modified in 7 days or fewer.
```
find ~ \( -iname '*jpeg' -o -iname '*jpg' \) -type f -mtime -7
```
### Taking action with xargs
The **xargs** command takes arguments from the standard input stream and executes a command based on them. Sticking with the example in the previous section, let’s say you want to copy all of the JPEG files in your home directory that have been modified in the last week to a thumb drive that you’ll attach to a digital photo display. Assume you already have the thumb drive mounted as _/media/photo_display_.
```
find ~ \( -iname '*jpeg' -o -iname '*jpg' \) -type f -mtime -7 -print0 | xargs -0 cp -t /media/photo_display
```
The **find** command is slightly modified from the previous version. The **-print0** command makes a subtle change on how the output is written: instead of using a newline, it adds a null character. The **-0** (zero) option to **xargs** adjusts the parsing to expect this. This is important because otherwise actions on file names that contain spaces, quotes, or other special characters may not work as expected. You should use these options whenever you’re taking action on files.
The **-t** argument to **cp** is important because **cp** normally expects the destination to come last. You can do this without **xargs** using **find**‘s **-exec** command, but the **xargs** method will be faster, especially with a large number of files, because it will run as a single invocation of **cp**.
### Find out more
This post only scratches the surface of what **find** can do. **find** supports testing based on permissions, ownership, access time, and much more. It can even compare the files in the search path to other files. Combining tests with Boolean logic can give you incredible flexibility to find exactly the files you’re looking for. With build in commands or piping to **xargs**, you can quickly process a large set of files.
_Portions of this article were previously published on [Opensource.com][3]._ _Photo by _[_Warren Wong_][4]_ on [Unsplash][5]_.
--------------------------------------------------------------------------------
via: https://fedoramagazine.org/command-line-quick-tips-locate-and-process-files-with-find-and-xargs/
作者：[Ben Cotton][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/bcotton/
[b]: https://github.com/lujun9972
[1]: https://fedoramagazine.org/wp-content/uploads/2018/10/commandlinequicktips-816x345.jpg
[2]: https://fedoramagazine.org/?s=command+line+quick+tips
[3]: https://opensource.com/article/18/4/how-use-find-linux
[4]: https://unsplash.com/@wflwong?utm_source=unsplash&utm_medium=referral&utm_content=creditCopyText
[5]: https://unsplash.com/s/photos/search?utm_source=unsplash&utm_medium=referral&utm_content=creditCopyText

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[#]: collector: (lujun9972)
[#]: translator: (geekpi)
[#]: reviewer: ( )
[#]: publisher: ( )
[#]: url: ( )
[#]: subject: (Command line quick tips: Locate and process files with find and xargs)
[#]: via: (https://fedoramagazine.org/command-line-quick-tips-locate-and-process-files-with-find-and-xargs/)
[#]: author: (Ben Cotton https://fedoramagazine.org/author/bcotton/)
命令行提示：使用 find 和 xargs 查找和处理文件
======
![][1]
**find** 是日常工具箱中功能更强大，更灵活的命令行程序之一。它如它名字所暗示的：查找符合你指定条件的文件和目录。借助 **-exec** 或 **-delete** 之类的参数，你可以让它对找到的文件进行操作。
在[命令行提示][2]系列的这一期中，你将会看到 **find** 命令的介绍，并学习如何使用内置命令或使用 **xargs** 命令处理文件。
### 查找文件
**find** 至少要加上查找的路径。例如，此命令将查找（并打印）系统上的每个文件：
```
find /
```
由于所有东西都是文件，因此你会看到大量的输出。这可能无法帮助你找到所需的内容。你可以更改路径参数缩小范围，但这实际上并没有比使用 **ls** 命令更好。因此，你需要考虑要查找的内容。
也许你想在家目录中查找所有 JPEG 文件。 **-name** 参数允许你将结果限制为与给定模式匹配的文件。
```
find ~ -name '*jpg'
```
但是等等！如果其中一些扩展名是大写怎么办？ **-iname** 类似于 **-name**，但不区分大小写：
```
find ~ -iname '*jpg'
```
很好！但是 8.3 命名方案出自 1985 年。某些图片的扩展名可能是 .jpeg。幸运的是，我们可以将模式使用“或”（**-o**）进行组合。括号会被转义，以便是 **find** 命令而不是 shell 程序尝试解释它们。
```
find ~ \( -iname 'jpeg' -o -iname 'jpg' \)
```
更进一步。如果你有一些以 jpg 结尾的目录怎么办？ （为什么你将目录命名为 **bucketofjpg** 而不是 **pictures**。）我们可以加上 **-type** 参数来仅查找文件：
```
find ~ \( -iname '*jpeg' -o -iname '*jpg' \) -type f
```
或者，也许你想找到那些名字奇怪的目录，以便之后可以重命名它们：
```
find ~ \( -iname '*jpeg' -o -iname '*jpg' \) -type d
```
最近你拍摄了很多照片，因此使用 **-mtime**（修改时间）将范围缩小到最近一周修改过的文件。 **-7** 表示 7 天或更短时间内修改的所有文件。
```
find ~ \( -iname '*jpeg' -o -iname '*jpg' \) -type f -mtime -7
```
### 使用 xargs 进行操作
**xargs** 命令从标准输入流中获取参数，并基于它们执行命令。继续使用上一节中的示例，假设你要将上周修改过的家目录中的所有 JPEG 文件复制到 U 盘，以便插到电子相册上。假设你已经将 U 盘挂载到 _/media/photo_display_。
```
find ~ \( -iname '*jpeg' -o -iname '*jpg' \) -type f -mtime -7 -print0 | xargs -0 cp -t /media/photo_display
```
**find**命令与以前的版本略有不同。**-print0** 命令让输出有一些更改：它不使用换行符，而是添加了一个空字符。**xargs** 的 **-0**（零）选项可调整解析以达到预期效果。这很重要，不然对包含空格、引号或其他特殊字符的文件名执行操作可能无法按预期进行。对文件采取任何操作时，都应使用这些选项。
**cp**的 **-t** 参数很重要，因为 **cp** 通常要求目的地址在最后。你可以不使用 **xargs** 而使用 **find** 的 **-exec** 执行此操作，但是 **xargs** 的方式会更快，尤其是对于大量文件，因为它会单次调用 **cp**。
### 了解更多
这篇文章仅是 **find** 可以做的事情的表面。 **find** 支持基于权限、所有者、访问时间等的测试。它甚至可以将搜索路径中的文件与其他文件进行比较。将测试与布尔逻辑相结合，可以为你提供惊人的灵活性，以精确地找到你要查找的文件。使用内置命令或管道传递给 **xargs**，你可以快速处理大量文件。
_这篇文章的部分内容先前已发布在 [Opensource.com][3]。_ _ 照片由 [_Warren Wong_][4] 在 [Unsplash] [5] 上发表。_
--------------------------------------------------------------------------------
via: https://fedoramagazine.org/command-line-quick-tips-locate-and-process-files-with-find-and-xargs/
作者：[Ben Cotton][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/bcotton/
[b]: https://github.com/lujun9972
[1]: https://fedoramagazine.org/wp-content/uploads/2018/10/commandlinequicktips-816x345.jpg
[2]: https://fedoramagazine.org/?s=command+line+quick+tips
[3]: https://opensource.com/article/18/4/how-use-find-linux
[4]: https://unsplash.com/@wflwong?utm_source=unsplash&utm_medium=referral&utm_content=creditCopyText
[5]: https://unsplash.com/s/photos/search?utm_source=unsplash&utm_medium=referral&utm_content=creditCopyText