Linux常用基本命令(xargs )

xargs:能够将管道或者标准输入传递的数据转换成xargs命令后面跟随的参数

ghostwu@dev:~/linux/cp$ ls
ghostwu_hardlink  ghostwu_home  ghostwu_softlink  ghostwu.txt
ghostwu@dev:~/linux/cp$ cat ghostwu.txt 
1 2 3
4 5 6 7
8 9 10
ghostwu@dev:~/linux/cp$ xargs < ghostwu.txt 
1 2 3 4 5 6 7 8 9 10

把ghostwu.txt文件的内容　通过输入重定向　传递给xargs，相当于echo 1 2 3 4 5 6 7 8 9 10

-n: 指定一行显示几个

ghostwu@dev:~/linux/cp$ xargs -n 2 < ghostwu.txt 
1 2
3 4
5 6
7 8
9 10

-d：指定分隔符

ghostwu@dev:~/linux/cp$ echo a-b-c-d
a-b-c-d
ghostwu@dev:~/linux/cp$ echo a-b-c-d | xargs -d -
a b c d

-i: 以{}替代前面的结果，经常跟find命令结合使用

把家目录下.py结尾的文件　复制　到tmp目录下

ghostwu@dev:~$ ls
Desktop    examples.desktop  linux  Pictures  python     tmp
Documents  git_test          Music  project   software   Videos
Downloads  info              php    Public    Templates
ghostwu@dev:~$ ls tmp
ghostwu@dev:~$ find . -name "*.py" | xargs -i cp -a {} tmp/
ghostwu@dev:~$ ls tmp
for.py    func3.py  func5.py  global2.py  while1.py
func2.py  func4.py  func.py   global.py   while.py

删除tmp下以.py结尾的文件

ghostwu@dev:~$ ls tmp
for.py    func3.py  func5.py  global2.py  while1.py
func2.py  func4.py  func.py   global.py   while.py
ghostwu@dev:~$ touch tmp/{a..f}.txt
ghostwu@dev:~$ ls tmp
a.txt  c.txt  e.txt   f.txt     func3.py  func5.py  global2.py  while1.py
b.txt  d.txt  for.py  func2.py  func4.py  func.py   global.py   while.py
ghostwu@dev:~$ find ./tmp -name "*.py" | xargs -i rm -rf {}
ghostwu@dev:~$ ls tmp
a.txt  b.txt  c.txt  d.txt  e.txt  f.txt

创建带空格的文件

ghostwu@dev:~/tmp$ touch "hello ghostwu.txt"
ghostwu@dev:~/tmp$ ls
a.txt  b.txt  c.txt  d.txt  e.txt  f.txt  hello ghostwu.txt
ghostwu@dev:~/tmp$ touch hi\ ghostwu.txt
ghostwu@dev:~/tmp$ ls
a.txt  b.txt  c.txt  d.txt  e.txt  f.txt  hello ghostwu.txt  hi ghostwu.txt
ghostwu@dev:~/tmp$ rm hello\ ghostwu.txt 
ghostwu@dev:~/tmp$ ls
a.txt  b.txt  c.txt  d.txt  e.txt  f.txt  hi ghostwu.txt
ghostwu@dev:~/tmp$ rm hi\ ghostwu.txt 
ghostwu@dev:~/tmp$ ls
a.txt  b.txt  c.txt  d.txt  e.txt  f.txt

不能删除带有空格的文件

ghostwu@dev:~/tmp$ ls
alltxt.tar.gz  b.txt  d.txt  f.txt              hi ghostwu.txt
a.txt          c.txt  e.txt  hello ghostwu.txt
ghostwu@dev:~/tmp$ find . -name "*.txt" | xargs rm
rm: cannot remove './hello': No such file or directory
rm: cannot remove 'ghostwu.txt': No such file or directory
rm: cannot remove './hi': No such file or directory
rm: cannot remove 'ghostwu.txt': No such file or directory
ghostwu@dev:~/tmp$ ls
alltxt.tar.gz  hello ghostwu.txt  hi ghostwu.txt

用man手册查找find 中 -print0选项

-print0
True; print the full file name on the standard output, followed
by a null character (instead of the newline character that
-print uses). This allows file names that contain newlines or
other types of white space to be correctly interpreted by pro‐
grams that process the find output. This option corresponds to
the -0 option of xargs.

意思大概就是 find 命令的-print0选项启用之后，会把文件名中包含换行或者其他空白字符正确的解释出来。这个选项通常跟 xargs 的 -0选项结合使用

所以，可以向下面这种方式，执行xargs 

ghostwu@dev:~/tmp$ ls
alltxt.tar.gz  b.txt  d.txt  f.txt              hi ghostwu.txt
a.txt          c.txt  e.txt  hello ghostwu.txt
ghostwu@dev:~/tmp$ find . -name "*.txt" -print0 | xargs -0 rm
ghostwu@dev:~/tmp$ ls
alltxt.tar.gz

查找家目录下面所有的.py文件，然后打包

ghostwu@dev:~/tmp$ ls
ghostwu@dev:~/tmp$ find ~ -name "*.py" | xargs tar cvf allpy.tar.gz
tar: Removing leading `/' from member names
/home/ghostwu/python/func2.py
/home/ghostwu/python/func3.py
/home/ghostwu/python/func4.py
/home/ghostwu/python/func.py
/home/ghostwu/python/global.py
/home/ghostwu/python/global2.py
/home/ghostwu/python/while.py
/home/ghostwu/python/for.py
/home/ghostwu/python/func5.py
/home/ghostwu/python/while1.py
ghostwu@dev:~/tmp$ ls
allpy.tar.gz
ghostwu@dev:~/tmp$ tar -tvf allpy.tar.gz 
-rw-rw-r-- ghostwu/ghostwu 179 2018-03-18 21:29 home/ghostwu/python/func2.py
-rw-rw-r-- ghostwu/ghostwu  58 2018-03-18 21:31 home/ghostwu/python/func3.py
-rw-rw-r-- ghostwu/ghostwu  81 2018-03-18 21:33 home/ghostwu/python/func4.py
-rw-rw-r-- ghostwu/ghostwu  44 2018-03-18 21:26 home/ghostwu/python/func.py
-rw-rw-r-- ghostwu/ghostwu 150 2018-03-18 21:53 home/ghostwu/python/global.py
-rw-rw-r-- ghostwu/ghostwu 124 2018-03-18 21:55 home/ghostwu/python/global2.py
-rw-rw-r-- ghostwu/ghostwu  90 2018-03-18 21:19 home/ghostwu/python/while.py
-rw-rw-r-- ghostwu/ghostwu  82 2018-03-18 21:08 home/ghostwu/python/for.py
-rw-rw-r-- ghostwu/ghostwu  99 2018-03-18 21:48 home/ghostwu/python/func5.py
-rw-rw-r-- ghostwu/ghostwu  92 2018-03-18 21:23 home/ghostwu/python/while1.py