[LINUX] If you don't know it, it's dangerous. Carefully explain how to use the xargs command

Basic

Click here for the video (click the image to go to youtube) [] watch? v = BnwD2rX9kv8)

xargs command

You can read a list from standard input or a file and pass it as an argument to the command you want to execute! By the way, the reading is generally "X-Agus". Since it is an abbreviation for arguments, it is taken from arguments (probably)

option

• -p: Check before execution
• -L: Execute with the specified number of arguments
• -I: Arguments can be passed to the specified position (There are others, but this is enough to remember)

appendix

• -L cannot be used because the -I option is always executed one by one.
• You can do the same with backquote

sample sample command

• ls | xargs wc
• find . -name "*.txt" | xargs wc
• ls | xargs -L 1 wc
• ls | xargs -L 3 wc
• ls | xargs -p -L 3 wc
• ls | xargs -I{} wc {}
• wc `ls`
• wc aaa.txt
• ls | wc
• ls | cat

Try to actually type the command

Prepare two files.

[bitnami@ /tmp/com_xargs]$ ls
aaa.txt  bbb.txt

The contents are like this

[bitnami@ /tmp/com_xargs]$ cat aaa.txt bbb.txt
asdf
qwer
34

qweriu
qweuf
werpoi

For example, try typing a command like this.

[bitnami@ /tmp/com_xargs]$ ls | xargs wc
 4  3 14 aaa.txt
 3  3 20 bbb.txt
 7  6 34 total

This is equivalent to typing the wc command on aaa.txt and bbb.txt. That is, "you can pass the result of ls to the wc command"

Let's check what kind of command is being executed with the -p option.

[bitnami@ /tmp/com_xargs]$ ls | xargs -p wc
wc aaa.txt bbb.txt ?...

As you can see, it says "wc aaa.txt bbb.txt? ...". You can see that you can pass the result of ls as an argument of the wc command. If you enter y here and press enter, it will be executed. (The -p option is convenient for debugging, so I definitely want to remember it)

By the way, if you are depressed without using xargs, this will happen.

[bitnami@ /tmp/com_xargs]$ ls | wc
      2       2      16

What this means is that you can think of it as passing the following result directly to the wc command (that is, it is easy to think of it as a file written as aaa.txt and bbb.txt).

(By the way, the meaning of the wc command is the number of lines, the number of words, the number of bytes from the left)

[bitnami@ /tmp/com_xargs]$ ls | cat
aaa.txt
bbb.txt