xargs命令

为啥必须要学会xargs命令？

• 主要原因是xargs的作用太大了，应用十分广泛，以下是平时工作中经常用到的一部分:
  • 读取文件并重新格式化
  • 配合wc统计文件行数
  • 查找文件后批量删除文件
  • 批量关闭进程
  • 批量修改文件的权限
  • 其它用法可使用xargs --help深入学习

[root@dev127 myb]# xargs --help
Usage: xargs [OPTION]... COMMAND INITIAL-ARGS...
Run COMMAND with arguments INITIAL-ARGS and more arguments read from input.Mandatory arguments to long options are mandatory for short options too.
Non-mandatory arguments are indicated by [square brackets]-0, --null                   Items are separated by a null, not whitespace.使用Disables quote and backslash processing-a, --arg-file=FILE          Read arguments from FILE, not standard input-d, --delimiter=CHARACTER    Input items are separated by CHARACTER, not byblank space. Disables quote and backslashprocessing-E END                       If END occurs as a line of input, the rest ofthe input is ignored.-e [END], --eof[=END]        Equivalent to -E END if END is specified.Otherwise, there is no end-of-file string--help                       Print a summary of the options to xargs.-I R                         same as --replace=R (R must be specified)-i,--replace=[R]             Replace R in initial arguments with namesread from standard input. If R isunspecified, assume {}-L,-l, --max-lines=MAX-LINES Use at most MAX-LINES nonblank input lines percommand line-l                           Use at most one nonblank input line percommand line-n, --max-args=MAX-ARGS      Use at most MAX-ARGS arguments per commandline-P, --max-procs=MAX-PROCS    Run up to max-procs processes at a time-p, --interactive            Prompt before running commands--process-slot-var=VAR       Set environment variable VAR in childprocesses-r, --no-run-if-empty        If there are no arguments, run no command.使用If this option is not given, COMMAND will berun at least once.-s, --max-chars=MAX-CHARS    Limit commands to MAX-CHARS at most--show-limits                Show limits on command-line length.-t, --verbose                Print commands before executing them--version                    Print the version number-x, --exit                   Exit if the size (see -s) is exceededReport bugs to <bug-findutils@gnu.org>.

xargs的使用

读取文件并重新格式化

• 例如下面的命令把一个4行4个字母格式化为1行了:

$ cat c.txt 
a
b
c
d
# zp @ zp-pc in ~/temp [21:02:54] 
$ cat c.txt |xargs
a b c d

• 格式化为每行2项:

$ cat c.txt |xargs -n2
a b
c d

• 指定分割符号-d:

$ echo "a;b;c;d" | xargs -d ";"
a b c d

统计文件行数

• 统计当前目录下所有文件的行数:

$ wc ./* -l40 ./b.txt4 ./c.txt130 ./tmp.txt174 total

• 等价于:

$ wc ./* -l40 ./b.txt4 ./c.txt130 ./tmp.txt174 total

查找并删除文件

• 查找a目录下的.txt结尾的文件并删除不询问

$ find ./a -name "*.txt" | xargs -i rm {}

• 查找a目录下的.log结尾的文件并询问是否删除:

$  find ./a -name "*.log" | xargs -p -i rm {}
rm ./a/lobby.20220118.log ?...y
rm ./a/lobby.20220118-2.log ?...y
rm ./a/lobby.20220117-3.log ?...y
rm ./a/lobby.20220117-2.log ?...y
rm ./a/lobby.20220118-3.log ?...y
rm ./a/lobby.20220118-1.log ?...y
rm ./a/lobby.20220115.log ?...y
rm ./a/lobby.20220117-5.log ?...y
rm ./a/lobby.20220117-1.log ?...y
rm ./a/lobby.20220116.log ?...y
rm ./a/lobby.20220117.log ?...y
rm ./a/lobby.20220117-4.log ?...y
rm ./a/lobby.20220117-6.log ?...y

批量修改文件的权限

• 批量修改当前目录下的lua文件把权限为755的改为644:

find ./ -name "*.lua" -perm 755 | xargs chmod 644

批量关闭进程

• 批量杀掉包含关键字"chrome"的进程:

ps -ef | grep chrome | grep "grep" -v |xargs kill
或
ps -ef | grep chrome | ag "ag" -v |xargs kill

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