xargs

Overview

xargs builds and executes command lines from stdin. Bridges tools that emit lists (find, grep -l) to commands that expect argv.

Syntax

xargs [options] [command [initial-arguments]]

Common Options

Option	Description
-0	NUL-delimited input
-n N	Max args per command
-P N	Parallel processes
-I {}	Replace string
-r	Do not run if empty (GNU)
-t	Print command before run
-p	Prompt

Safety

Unquoted newlines/spaces break default splitting — prefer find -print0 | xargs -0. Be careful with xargs rm.

Examples with Explanations

Safe with find

find . -name '*.log' -print0 | xargs -0 -r ls -l
find . -name '*.tmp' -print0 | xargs -0 -r rm -v

Placeholder

echo -e 'a\nb' | xargs -I{} cp {} {}.bak

Parallel gzip

find . -name '*.log' -print0 | xargs -0 -n 1 -P 4 gzip

Lines as args

xargs -a urls.txt -n 1 curl -O

Related Commands

• find -exec — often enough alone
  
• parallel — GNU parallel for complex jobs
  
• while read — bash loops