XARGS(1) findutils XARGS(1)
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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.
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--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 [dq][dq] 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
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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.
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-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.
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--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
Generates a compact listing of all the users on the system.
EXIT STATUS
xargs exits with the following status:
0 if it succeeds (and any commands run by xargs, if there were
any, exited normally with exit status 0).
123 if any invocation of the command exited with status other
than 0 or 255 (though see below).
124 if the command exited with status 255
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125 if the command is killed by a signal
126 if the command cannot be run
127 if the command is not found
1 if some other error occurred.
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.
OPTIONS
Options specified in IEEE Std 1003.1, 2024 are -E, -I, -L, -n, -p, -r,
-s, -t, -x and -0.
-E Since findutils 4.2.9 (2004), GNU xargs has had no default
logical end-of-file string. This may not be true of other
implementations, so you should use -E [dq][dq] to be certain.
-e Removed from POSIX in IEEE Std 1003.1, 2004. GNU xargs still
supports this, but you should use -E instead.
-i Removed from POSIX in IEEE Std 1003.1, 2004. GNU xargs still
supports this but you should use -I instead.
-l Removed from POSIX in IEEE Std 1003.1, 2004. GNU xargs still
supports this but you should use -L instead.
-o An extension to the POSIX standard for better compatibility with
BSD. Not in POSIX.
-p A GNU extension since before 1994. Added to POSIX in IEEE Std
1003.1, 2004.
-r A GNU extension since before 1994. Added to POSIX in IEEE Std
1003.1, 2024.
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-0 A GNU extension since before 1994. Added to POSIX in IEEE Std
1003.1, 2024.
EXEC SYSTEM CALL LIMITS
The POSIX standard allows implementations to have a limit on the size
of arguments to the exec functions. This limit could be as low as
4096 bytes including the size of the environment. For scripts to be
portable, they must not rely on a larger value. However, I know of no
implementation whose actual limit is that small. The --show-limits
option can be used to discover the actual limits in force on the
current system.
POSIX EXIT STATUS REQUIREMENTS
The POSIX standard specifies that certain kinds of problem must result
in particular xargs return values. The table below summarizes how
these requirements relate to the values listed in the EXIT STATUS
section. box,tab(|); Cb S |Cb S Lb Lb|Lb Lb Lt Nt|Nt Lt. T{
POSIX requirement T}|T{ GNU xargs behavior T} Situation|T{ Exit status
T}|T{ Exit status T}|Details _|_|_|_ T{ Utility not found
T}|127|127|T{ execvp(2) failed with errno value ENOENT T} _|_|_|_ T{
Utility could not be invoked T}|126|126|T{ execvp(2) failed with any
other error T} _|_|_|_ T{ Any other non-success case T}|1 - 125|125|T{
Utility killed by a fatal signal T} ||124|T{ Utility exited with
status 255 T} ||123|T{ Utility exited with a status other than 0 or
255 T} ||2 - 122|T{ May be used in the future T} ||1|T{ Any other kind
of error (such as a usage error) T} _|_|_|_ T{ Successful completion
T}|0|0|
CONFORMANCE BUGS
tab(|); Lb Lb Lb L L Lx. Introduced|Fixed|Description 4.5.10
(2011)|4.10.0 (2024)|T{ SIGUSR1 should be a fatal signal by default,
but SIGUSR1 would not kill xargs even if the -P option was not in use.
T}
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
SECURITY
It is not possible for xargs to be used securely, since there will
always be a time gap between the production of the list of input files
and their use in the commands that xargs issues. If other users have
access to the system, they can manipulate the filesystem during this
time window to force the action of the commands xargs runs to apply to
files that you didn't intend. For a more detailed discussion of this
and related problems, please refer to the Security Considerations
chapter in the findutils Texinfo documentation. The -execdir option
of find can often be used as a more secure alternative.
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IMPLEMENTATION LIMITS
When you use the -I option, each line read from the input is buffered
internally. This means that there is an upper limit on the length of
input line that xargs will accept when used with the -I option. To
work around this limitation, you can use the -s option to increase the
amount of buffer space that xargs uses, and you can also use an extra
invocation of xargs to ensure that very long lines do not occur. For
example:
somecommand | xargs -s 50000 echo
Here, the first invocation of xargs has no input line length limit
because it doesn't use the -i option. The second invocation of xargs
does have such a limit, but we have ensured that it never encounters a
line which is longer than it can handle. This is not an ideal
solution. Instead, the -i option should not impose a line length
limit, which is why this discussion appears in the BUGS section. The
problem doesn't occur with the output of find(1) because it emits just
one filename per line.
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:
<https://savannah.gnu.org/bugs/?group=findutils>
General topics about the GNU findutils package are discussed at the
bug-findutils mailing list:
<https://lists.gnu.org/mailman/listinfo/bug-findutils>
COPYRIGHT
Copyright c 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
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