NAME

xargs - build and execute command lines from standard input

SYNOPSIS

xargs [option ...] [command] [initial-argument ...]

DESCRIPTION

This manual page documents the GNU version of xargs. xargs reads items from the standard input, delimited by blanks (which can be protected with double or single quotes or a backslash) or newlines, and executes the command (default is echo) one or more times with any initial-arguments followed by items read from standard input. Blank lines on the standard input are ignored.

The command line for command is built up until it reaches a system-defined limit (unless the -n and -L options are used). The specified command will be invoked as many times as necessary to use up the list of input items. In general, there will be many fewer invocations of command than there were items in the input. This will normally have significant performance benefits. Some commands can usefully be executed in parallel too; see the -P option.

Because Unix filenames can contain blanks and newlines, this default behaviour is often problematic; filenames containing blanks and/or newlines are incorrectly processed by xargs. In these situations it is better to use the -0 option, which prevents such problems. When using this option you will need to ensure that the program which produces the input for xargs also uses a null character as a separator. If that program is GNU find for example, the -print0 option does this for you.

If any invocation of the command exits with a status of 255, xargs will stop immediately without reading any further input. An error message is issued on standard error when this happens.

OPTIONS

-0

--null

Input items are terminated by a null character instead of by whitespace, and the quotes and backslash are not special (every character is taken literally). Disables the end-of-file string, which is treated like any other argument. Useful when input items might contain white space, quote marks, or backslashes. The GNU find (and from POSIX Issue 8, IEEE Std 1003.1, 2024) -print0 option produces input suitable for this mode.

-a file

--arg-file=file

Read items from file instead of standard input. If you use this option, standard input remains unchanged when commands are run. Otherwise, standard input is redirected from /dev/null.

--delimiter=delim

-d delim

Input items are terminated by the specified character. The specified delimiter may be a single character, a C-style character escape such as \n, or an octal or hexadecimal escape code. Octal and hexadecimal escape codes are understood as for the printf command. Multibyte characters are not supported. When processing the input, quotes and backslash are not special; every character in the input is taken literally. The -d option disables any end-of-file string, which is treated like any other argument. You can use this option when the input consists of simply newline-separated items, although it is almost always better to design your program to use --null where this is possible.

-E eof-str

Set the end-of-file string to eof-str. If the end-of-file string occurs as a line of input, the rest of the input is ignored. If neither -E nor -e is used, no end-of-file string is used. Other implementations of xargs may have a default logical end-of-file string, so if you want to portably ensure that no logical end-of-file string is in use, use -E "" to disable the logical end-of-file string. See also STANDARDS CONFORMANCE.

-e[eof-str]

--eof[=eof-str]

This option is a synonym for the -E option. Use -E instead, because it is still POSIX-compliant whereas the -e option was removed from the POSIX standard (IEEE Std 1003.1, 2004 Edition).

-I replace-str

Replace occurrences of replace-str in the initial-arguments with names read from standard input. Also, unquoted blanks do not terminate input items; instead the separator is the newline character. Implies -x and “-L 1”.

-i[replace-str]

--replace[=replace-str]

This option is a synonym for -Ireplace-str if replace-str is specified. If the replace-str argument is missing, the effect is the same as “-I{}”. The -i option was removed from the POSIX standard (IEEE Std 1003.1, 2004 Edition). Use -I instead.

-L max-lines

Use at most max-lines nonblank input lines per command line. Trailing blanks cause an input line to be logically continued on the next input line. Implies -x.

-l[max-lines]

--max-lines[=max-lines]

Synonym for the -L option. Unlike -L, the max-lines argument is optional. If max-lines is not specified, it defaults to one. The -l option is deprecated since the POSIX standard specifies -L instead.

-n max-args

--max-args=max-args

Use at most max-args arguments per command line. Fewer than max-args arguments will be used if the size (see the -s option) is exceeded, unless the -x option is given, in which case xargs will exit.

-P max-procs

--max-procs=max-procs

Run up to max-procs processes at a time; the default is 1. If max-procs is 0, xargs will run as many processes as possible at a time. Use the -n option or the -L option with -P; otherwise chances are that only one exec will be done. While xargs is running, you can send its process a SIGUSR1 signal to increase the number of commands to run simultaneously, or a SIGUSR2 to decrease the number. You cannot increase it above an implementation-defined limit (which is shown with --show-limits). You cannot decrease it below 1. xargs never terminates its commands; when asked to decrease, it merely waits for more than one existing command to terminate before starting another. xargs always waits for all child processes to exit before exiting itself (but see BUGS).

If you do not use the -P option, xargs will not handle the SIGUSR1 and SIGUSR2 signals, meaning that they will terminate the program (unless they were blocked in the parent process before xargs was started).

Please note that it is up to the called processes to properly manage parallel access to shared resources. For example, if more than one of them tries to print to standard output, the output will be produced in an indeterminate order (and very likely mixed up) unless the processes collaborate in some way to prevent this. Using some kind of locking scheme is one way to prevent such problems. In general, using a locking scheme will help ensure correct output but reduce performance. If you don't want to tolerate the performance difference, simply arrange for each process to produce a separate output file (or otherwise use separate resources).

-o

--open-tty

Reopen standard input as /dev/tty in the child process before executing the command. This is useful if you want xargs to run an interactive application.

-p

--interactive

Prompt the user about whether to run each command line and read a line from the terminal. Only run the command line if the response starts with `y' or `Y'. Implies -t.

--process-slot-var=name

Set the environment variable name to a unique value in each running child process. Values are reused once child processes exit. This can be used in a rudimentary load distribution scheme, for example.

-r

--no-run-if-empty

If the standard input does not contain any nonblanks, do not run the command. Normally, the command is run once even if there is no input.

-s max-chars

--max-chars=max-chars

Use at most max-chars characters per command line, including the command and initial-arguments and the terminating nulls at the ends of the argument strings. The largest allowed value is system-dependent, and is calculated as the argument length limit for exec, less the size of your environment, less 2048 bytes of headroom. If this value is more than 128 KiB, 128 KiB is used as the default value; otherwise, the default value is the maximum. 1 KiB is 1024 bytes. xargs automatically adapts to tighter constraints.

--show-limits

Display the limits on the command-line length which are imposed by the operating system, xargs' choice of buffer size and the -s option. Pipe the input from /dev/null (and perhaps specify --no-run-if-empty) if you don't want xargs to do anything.

-t

--verbose

Print the command line on the standard error output before executing it.

-x

--exit

Exit if the size (see the -s option) is exceeded.

--

Delimit the option list. Later arguments, if any, are treated as operands even if they begin with “-”. For example, “xargs -- --help” runs the command --help (found in PATH) instead of printing the usage text, and “xargs -- --mycommand” runs the command --mycommand instead of rejecting this as unrecognized option.

--help

Print a summary of the options to xargs and exit.

--version

Print the version number of xargs and exit.

The options --max-lines (-L, -l), --replace (-I, -i), and --max-args (-n) are mutually exclusive. If some of them are specified at the same time, then xargs will generally use the option specified last on the command line, i.e., it will reset the value of the offending option (given before) to its default value. Additionally, xargs will issue a warning diagnostic on standard error. The exception to this rule is that the special max-args value “1” (as in “-n1”) is ignored after the --replace option and its aliases -I and -i, because it would not actually conflict.

EXAMPLES

find /tmp -name core -type f -print | xargs /bin/rm -f

Find files named core in or below the directory /tmp and delete them. Note that this will work incorrectly if there are any filenames containing newlines or spaces.

find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f

Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing spaces or newlines are correctly handled.

find /tmp -depth -name core -type f -delete

Find files named core in or below the directory /tmp and delete them, but more efficiently than in the previous example (because we avoid the need to use fork(2) and exec(2) to launch rm and we don't need the extra xargs process).

cut -d: -f1 < /etc/passwd | sort | xargs echo

EXIT STATUS

xargs exits with the following status:

It is possible that future versions of xargs may exit with a status in the range 1–125 when the command it launched fails in some specific way not listed above. Nevertheless, xargs will comply with POSIX. The STANDARDS CONFORMANCE section explains the POSIX rules about the exit status of xargs.

The commands run by xargs are run directly (with execvp(2)) rather than being invoked via the shell. The shell's (128 + signal) convention for reporting that a process had been killed by a signal is not used by xargs.

STANDARDS CONFORMANCE

This section describes the relationship between GNU xargs and the standards with which it complies. Some portability considerations are mentioned.

HISTORY

The xargs program was invented by Herb Gellis at Bell Labs. See the Texinfo manual for findutils, chapter “Finding Files”, for more information.

BUGS

REPORTING BUGS

GNU findutils online help: https://www.gnu.org/software/findutils/#get-help
Report any translation bugs to https://translationproject.org/team/

Report any other issue via the form at the GNU Savannah bug tracker:

COPYRIGHT

Copyright © 1990–2026 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later https://gnu.org/licenses/gpl.html.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.

SEE ALSO

find(1), kill(1), locate(1), updatedb(1), fork(2), execvp(3), locatedb(5), signal(7)

Full documentation https://www.gnu.org/software/findutils/xargs
or available locally via: info xargs