xargs

Updated

September 4, 2026

Overview

xargs builds and executes command lines from standard input. It bridges tools that emit lists (files, IDs, URLs) to commands that expect argv parameters. Essential in pipelines with find, git, and text filters — and easy to get wrong with spaces or special characters unless you use NUL-delimited mode.

Syntax

command | xargs [options] [utility [args...]]
xargs [options] -a file [utility [args...]]

If utility is omitted, xargs defaults to /bin/echo.

Common Options

Option	Description
`-0` / `--null`	Input items are NUL-separated (safe for arbitrary filenames)
`-n N`	At most N args per command invocation
`-n 1`	One arg per invocation
`-P N`	Run up to N processes in parallel
`-I {}`	Replace `{}` in the command template with each item
`-i`	Like `-I {}` (deprecated form on some systems)
`-t`	Print the command before running it
`-p`	Prompt before each command
`-r`	Do not run if stdin is empty (GNU)
`-d delim`	Input delimiter (GNU)
`-L N`	Use at most N lines per command
`-a file`	Read items from file instead of stdin
`-x`	Exit if a single item is too long for the command line

Safety

Never pipe raw find output into bare xargs when names may contain spaces or newlines. Use find … -print0 | xargs -0 ….
xargs splits on whitespace by default — a filename my file.txt becomes two arguments.
Parallel -P can overwhelm disks, APIs, or remote hosts; start low.
Interactive prompts (-p) are for humans; do not use in unattended scripts without care.

Examples with Explanations

Basic: echo words as args

echo 'one two three' | xargs
# runs: echo one two three

Delete files listed by find (NUL-safe)

find /tmp -name '*.tmp' -print0 | xargs -0 rm -f

Equivalent modern find:

find /tmp -name '*.tmp' -delete

One invocation per item with placeholder

find . -name '*.md' -print0 | xargs -0 -I {} cp {} /backup/docs/

-I {} forces one item at a time and allows the placeholder anywhere in the command.

Limit batch size

cat ids.txt | xargs -n 50 echo
# or feed a real tool:
cat ids.txt | xargs -n 100 my-bulk-api-delete

Avoids “argument list too long” and huge single CLI lines.

Parallel compression

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

Four gzip workers, one file each.

Show commands (`-t`) while learning

printf 'a\nb\nc\n' | xargs -n 1 -t rm -f

Skip empty input (GNU)

grep -rl 'obsolete' . | xargs -r rm
# better NUL-safe:
grep -rlZ 'obsolete' . | xargs -0 -r rm

Without -r, some xargs still run the command once with no args — dangerous for rm.

Lines as items (GNU `-d`)

xargs -d '\n' -n 1 echo < urls.txt

Still fails if lines contain embedded newlines (rare); for filenames prefer NUL.

Placeholders with multiple uses

cat hosts.txt | xargs -I% sh -c 'ssh % "hostname; uptime"'

Quote carefully; prefer a real loop for complex remote commands.

From a file directly

xargs -a packages.txt -n 1 sudo apt-get install -y

(Still review package lists before mass installs.)

Combine with git

git ls-files -z '*.png' | xargs -0 ls -l
git grep -z -l 'TODO' | xargs -0 "$EDITOR"

Understanding Output

xargs itself is quiet unless -t/-p is set; you see the utility’s stdout/stderr. Exit status is non-zero if any invocation fails (details vary; with -P, failures can interleave). Use -t when a pipeline “does nothing” — often the built command is not what you expected.

Notes & Pitfalls

NUL safety is the professional default for file paths: -print0 / -z / -Z upstream + xargs -0.
-I {} implies -n 1 and disables some batching; good for clarity, slower for huge sets.
Quoting inside sh -c with xargs is a common injection footgun — validate input or avoid sh -c when possible.
“Argument list too long” (E2BIG) is exactly what batching with -n fixes.
Busybox or non-GNU xargs may lack -0, -r, -a, -d, or -P. On Ubuntu GNU findutils xargs, these are available.
For complex per-file logic, a while IFS= read -r -d '' f; do …; done loop is often clearer than nested xargs.

Additional Resources

man xargs
man find (especially -print0, -exec)