xargs(1) — Linux manual page


XARGS(1)                 General Commands Manual                XARGS(1)

NAME         top

       xargs - build and execute command lines from standard input

SYNOPSIS         top

       xargs [options] [command [initial-arguments]]

DESCRIPTION         top

       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 new‐
       lines, 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 sys‐
       tem-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 op‐

       Because Unix filenames can contain blanks and newlines, this de‐
       fault 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 exam‐
       ple, 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 stderr when this happens.

OPTIONS         top

       -0, --null
              Input items are terminated by a null character instead of
              by whitespace, and the quotes and backslash are not spe‐
              cial (every character is taken literally).  Disables the
              end-of-file string, which is treated like any other argu‐
              ment.  Useful when input items might contain white space,
              quote marks, or backslashes.  The GNU find (and from Issue
              8, POSIX) -print0 option produces input suitable for this

       -a file, --arg-file=file
              Read items from file instead of standard input.  If you
              use this option, stdin remains unchanged when commands are
              run.  Otherwise, stdin 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 hexadec‐
              imal escape code.  Octal and hexadecimal escape codes are
              understood as for the printf command.  Multibyte charac‐
              ters are not supported.  When processing the input, quotes
              and backslash are not special; every character in the in‐
              put 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 bet‐
              ter to design your program to use --null where this is

       -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.

       -e[eof-str], --eof[=eof-str]
              This option is a synonym for the -E option.  Use -E in‐
              stead, because it is POSIX compliant while this option is
              not.  If eof-str is omitted, there is no end-of-file
              string.  If neither -E nor -e is used, no end-of-file
              string is used.

       -I replace-str
              Replace occurrences of replace-str in the initial-argu‐
              ments 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 is deprecated;
              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 argu‐
              ment is optional.  If max-lines is not specified, it de‐
              faults 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 ex‐
              isting 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 termi‐
              nate 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 prop‐
              erly manage parallel access to shared resources.  For ex‐
              ample, if more than one of them tries to print to stdout,
              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

       -o, --open-tty
              Reopen stdin as /dev/tty in the child process before exe‐
              cuting 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.

              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.  This option is a GNU exten‐

       -s max-chars, --max-chars=max-chars
              Use at most max-chars characters per command line, includ‐
              ing 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 val‐
              ue; otherwise, the default value is the maximum.  1 KiB is
              1024 bytes.  xargs automatically adapts to tighter con‐

              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 exam‐
              ple, xargs -- --help runs the command --help (found in
              PATH) instead of printing the usage text, and xargs --
              --mycommand runs the command --mycommand instead of re‐
              jecting this as unrecognized option.

       --help Print a summary of the options to xargs and exit.

              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 speci‐
       fied last on the command line, i.e., it will reset the value of
       the offending option (given before) to its default value.  Addi‐
       tionally, xargs will issue a warning diagnostic on stderr.  The
       exception to this rule is that the special max-args value 1
       ('-n1') is ignored after the --replace option and its aliases -I
       and -i, because it would not actually conflict.

EXAMPLES         top

       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         top

       xargs exits with the following status:

              0      if it succeeds

              123    if any invocation of the command exited with status

              124    if the command exited with status 255

              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.

       Exit codes greater than 128 are used by the shell to indicate
       that a program died due to a fatal signal.


       The long-standing -0 option of xargs will be included in Issue 8
       of the POSIX standard.

       As of GNU xargs version 4.2.9, the default behaviour of xargs is
       not to have a logical end-of-file marker.  POSIX (IEEE Std
       1003.1, 2004 Edition) allows this.

       The -l and -i options appear in the 1997 version of the POSIX
       standard, but do not appear in the 2004 version of the standard.
       Therefore you should use -L and -I instead, respectively.

       The -o option is an extension to the POSIX standard for better
       compatibility with BSD.

       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 ac‐
       tual limits in force on the current system.

       In versions of xargs up to and including version 4.9.0, SIGUSR1
       and SIGUSR2 would not cause xargs to terminate even if the -P op‐
       tion was not used.

HISTORY         top

       The xargs program was invented by Herb Gellis at Bell Labs.  See
       the Texinfo manual for findutils, Finding Files, for more infor‐

BUGS         top

       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.

       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 | xargs -I '{}' -s 100000 rm

       Here, the first invocation of xargs has no input line length lim‐
       it because it doesn't use the -i option.  The second invocation
       of xargs does have such a limit, but we have ensured that it nev‐
       er 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.

       In versions of xargs up to and including version 4.9.0, xargs -P
       would exit while some of its children were still running, if one
       of them exited with status 255.

REPORTING BUGS         top

       GNU findutils online help: <https://www.gnu.org/software/findu‐
       Report any translation bugs to <https://translationpro‐

       Report any other issue via the form at the GNU Savannah bug
       General topics about the GNU findutils package are discussed at
       the bug-findutils mailing list:

COPYRIGHT         top

       Copyright © 1990–2024 Free Software Foundation, Inc.  License
       GPLv3+: GNU GPL version 3 or later <https://gnu.org/licens‐
       This is free software: you are free to change and redistribute
       it.  There is NO WARRANTY, to the extent permitted by law.

SEE ALSO         top

       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

COLOPHON         top

       This page is part of the findutils (find utilities) project.  In‐
       formation about the project can be found at 
       ⟨http://www.gnu.org/software/findutils/⟩.  If you have a bug
       report for this manual page, see
       ⟨https://savannah.gnu.org/bugs/?group=findutils⟩.  This page was
       obtained from the project's upstream Git repository
       ⟨git://git.savannah.gnu.org/findutils.git⟩ on 2024-06-14.  (At
       that time, the date of the most recent commit that was found in
       the repository was 2024-06-03.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to


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