$ Linux Command

Shell

xargs

Build command lines from standard input.

pipeargumentscommandfilesparallelbatch

Additional Notes

xargs builds command lines from standard input. It converts input items (one per line by default) into arguments for another command, which enables batch processing and parallel execution in pipelines.

By default xargs splits input on whitespace and runs the command once with many arguments. Use -0 with null-separated input from find -print0 to handle filenames with spaces or newlines safely.

Syntax

command | xargs [options] [command [initial-args]]

Parameters

  • options: Flags that change how xargs behaves.
  • command: Command to run for the input items.
  • initial-args: Fixed arguments placed before the items from input.

Common Options

  • -0: Read null-separated input instead of newline-separated.
  • -n N: Use at most N input items per command line.
  • -L N: Use N input lines per command line.
  • -I {}: Replace {} with each input item.
  • -d DELIM: Use a custom input delimiter.
  • -a FILE: Read items from a file instead of standard input.
  • -r: Do not run the command if input is empty.
  • -P N: Run up to N commands in parallel.
  • -p: Prompt before running each command.
  • -t: Print each command before running it.

Examples

printf "%s\n" one two | xargs echo

Join the items into one echo command: echo one two.

find . -name "*.log" -print0 | xargs -0 rm

Delete every matching file safely, even with spaces in names.

printf "%s\n" app db | xargs -I {} echo "restart {}"

Run a command per item, substituting {} each time.

ls *.jpg | xargs -n 1 -I {} cp {} /backups/{}.bak

Copy each file to a renamed backup path.

cat hosts.txt | xargs -P 4 -I {} ping -c 1 {}

Ping each host in parallel with up to 4 concurrent processes.

find . -type f -name "*.tmp" | xargs -r rm

Remove temp files only if any were found.

ls | xargs -t -n 2 mv {} /tmp

Echo each constructed command before running it.

Practical Notes

  • Prefer find -print0 | xargs -0 over plain newlines when filenames may contain spaces.
  • -I {} runs one command per item; without it xargs batches many items into fewer runs.
  • Use -P N for slow commands (pings, downloads, builds) to speed up batches.
  • -r avoids running the command with no arguments when input is empty.
  • -t and -p are handy for checking destructive commands before they run.