Shell之Xargs命令

😄 Written by Zak Zhu

学习python风格, 优雅规范书写shell代码

Shell之Xargs命令

参考

菜鸟教程/Linux xargs命令(https://www.runoob.com/linux/linux-comm-xargs.html)
程序猿小卡_casper/Linux基础: xargs命令(https://segmentfault.com/a/1190000012566053)
xargs命令_Linux xargs命令: 一个给其他命令传递参数的过滤器(http://c.biancheng.net/linux/xargs.html)
阮一峰的网络日志/xargs 命令教程(https://www.ruanyifeng.com/blog/2019/08/xargs-tutorial.html)
Ein Verne/每天学习一个命令: xargs(http://einverne.github.io/post/2019/06/xargs.html)

xargs命令简介

xargs reads items from the standard input, delimited by blanks or newlines, and executes the command (default is /bin/echo) one or more times with any initial-arguments followed by items read from standard input.

xargs命令格式

语法:

SOMECOMMAND | xargs [OPTION]... COMMAND [INITIAL-ARGS]...

参数:

-0, --null		                # Input items are terminated by a null, not whitespace

-d CHAR, --delimiter=CHAR		# Input items are terminated by the specified character

-I R 		                    # replace 'R' in INITIAL-ARGS with names read from standard input; if 'R' is unspecified, assume '{}'
	
-n X				            # use X arguments per command

-p								# prompt before runing commands

-t, --verbose					# print commands before executing them

xargs实例说明

xargs后面的命令默认是echo
```
echo "hello world !" | xargs
```
从文件中一行行读取文件名并创建
```
cat filenames | xargs -t -d "\n" touch
```
查找日志文件(文件名包含空格)并删除

思路:
- find命令查找出以.log结尾的文件, 考虑到文件名可能包含空格, 用-print0参数把找到的文件以null分隔
- xargs命令的-0参数用null作分隔符, 然后删除
```
find /tmp -name "*.log" -type f -print0 | xargs -t -0 rm
```
把以.py结尾的文件, 修改成.py.bak结尾
```
ls *.py | xargs -t -I {} mv {} {}.bak
```
读取输入数据重新格式化后输出
```
cat test | xargs -n 3
```
xargs在传参前逐个提示确认
```
ls /tmp | xargs -n 1 -p rm -rf
```