xargs

Run command with arguments from stdin

$ echo [file1 file2] | xargs rm

$ echo "[a:b:c]" | xargs -d ":" echo

$ find . -name "*.txt" | xargs -I {} cp {} [/backup/]

$ find . -name "*.jpg" | xargs -P [4] -I {} convert {} {}.png

$ find . -name "*.txt" -print0 | xargs -0 rm

$ echo {1..100} | xargs -n [10] echo

$ find . -name "*.tmp" | xargs -p rm

$ echo "" | xargs -r echo "not empty"

xargs [-I replace] [-n max-args] [-P max-procs] [-0] [-d delim] [command]

xargs builds and executes commands from standard input. It converts input into arguments for a command, handling batching, parallelization, and argument limits.
By default, xargs appends all input as arguments to a single command invocation. The -n option limits arguments per invocation, running the command multiple times.
The -I flag enables argument placement anywhere in the command. {} (or any placeholder) is replaced with each input item. This runs the command once per input item.
Parallel execution (-P) runs multiple commands simultaneously. Combined with -n or -I, this processes items concurrently, utilizing multiple CPU cores.
Null-delimited input (-0) handles filenames with spaces, newlines, or special characters safely. Use with find -print0 or similar tools.
Without -r, xargs runs the command even with empty input. The -r flag prevents this, useful when empty input would cause errors.

-I REPLACE

Replace string in command.

Maximum arguments per command.

Parallel processes.

Input items are null-terminated.

Input delimiter character.

Prompt before each execution.

Print commands before execution.

Don't run if input is empty.

Use NUM lines per command.

Maximum command line length.

Read arguments from file.

Exit if command line too long.

Show system limits.

Special characters in filenames cause issues without -0. Shell features (pipes, redirects) need wrapper scripts. Argument limit depends on system. Error handling across parallel jobs is limited. Order not preserved with -P.

xargs originated in PWB/UNIX in the 1970s. It addressed the limitation of shell command line length - programs couldn't accept unlimited arguments. The tool became essential for chaining Unix commands, enabling "do something to many files" patterns that define Unix philosophy.

find(1), parallel(1), apply(1)