xargs

xargs linux command cheatsheet by Thamizhiniyan C S

Introduction

xargs is a command line tool used to build and execute command from the standard input.

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Syntax

xargs [-p t x ] [-e [EOFString]] [-E EOFString] [-i [ReplaceString] ] [-I ReplaceString | -L Number | -n Number] [ -l [ Number]] [-s Size] [Command [Argument ... ]]

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Important Flags

Flags	Description
-0	Will terminate the arguments with null character (helps to handle spaces in the argument)
-a file	This option allows xargs to read item from a file
-d delimiter	To specify the delimiter to be used when differentiating arguments in stdin
-L int	Specifies max number non-blank inputs per command line
-s int	Consider this as a buffer size that you allocate while running xargs, it sets the max-chars for the command, which includes it's initial arguments and terminating nulls as well.(You won't be using this most of the times but it's good to know). Default size is around 128kB (if not specified).
-x	This flag will exit the command execution if the size specified is exceeded.(For security purposes.)
-E str	This is to specify the end-of-file string (You can use this in case you are reading arguments from a file)
-I str	(Capital i) Used to replace str occurrence in arguments with the one passed via stdin(More like creating a variable to use later)
-p	prompt the user before running any command as a token of confirmation.
-r	If the standard input is blank (i.e. no arguments passed) then it won't run the command.
-n int	This specifies the limit of max-args to be taken from command input at once. After the max-args limit is reached, it will pass the rest arguments into a new command line with the same flags issued to the previously ran command. (More like a looping)
-t	verbose; (Print the command before running it).Note: This won't ask for a prompt

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Examples

Command	Description
echo 'file1 file2 file3' | xargs -t -I argVar sh -c '{ touch argVar; ls -l argVar;}'	To run multiple commands in one line
find ./ -type f -print0 | xargs -0 -t -p rm -f	To find and delete files with a prompt
find ./ -type f -print0 | xargs -0 egrep '^r\w*0$'	Looking out for files with the given pattern of words
cat file | xargs -I files -t sh -c "touch files; chmod 664 files"	To create files and change its permission to read-only to the owner
ls | xargs -I word -n 1 -t sh -c "echo word >> shortrockyou; rm word"	To list the directory, append all the names of the files in the directory to a file and remove those files.