XARGS(1) General Commands Manual XARGS(1)
NAME
 xargs - build and execute command lines from standard input
SYNOPSIS
 xargs [options] [command [initial-arguments]]
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 /bin/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-de-
 fined 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 exe-
 cuted 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 new-
 lines 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 stderr 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 -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, stdin remains unchanged when commands are run. Other-
 wise, 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 charac-
 ter 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; ev-
 ery 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 possi-
 ble.
 -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 ig-
 nored. 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 instead, be-
 cause 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-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{}. This 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 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 implemen-
 tation-defined limit (which is shown with --show-limits). You
 cannot decrease it below 1. xargs never terminates its com-
 mands; when asked to decrease, it merely waits for more than one
 existing command to terminate before starting another.
 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 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 sep-
 arate resources).
 -o, --open-tty
 Reopen stdin as /dev/tty in the child process before executing
 the command. This is useful if you want xargs to run an inter-
 active 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 re-
 sponse starts with `y' or `Y'. Implies -t.
 --process-slot-var=name
 Set the environment variable name to a unique value in each run-
 ning child process. Values are reused once child processes ex-
 it. 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 extension.
 -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 sys-
 tem-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 128KiB, 128Kib is used as
 the default value; otherwise, the default value is the maximum.
 1KiB is 1024 bytes. xargs automatically adapts to tighter con-
 straints.
 --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 exe-
 cuting it.
 -x, --exit
 Exit if the size (see the -s option) is exceeded.
 --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 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
 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 con-
 taining 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 con-
 taining 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 ex-
 tra 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
 123 if any invocation of the command exited with status 1-125
 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.
STANDARDS CONFORMANCE
 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 Edi-
 tion) 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 compati-
 bility 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 porta-
 ble, they must not rely on a larger value. However, I know of no im-
 plementation whose actual limit is that small. The --show-limits op-
 tion can be used to discover the actual limits in force on the current
 system.
BUGS
 It is not possible for xargs to be used securely, since there will al-
 ways 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 limit be-
 cause 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 solu-
 tion. 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/findu-
 tils/#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) 1990-2021 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), locat-
 edb(5), signal(7)
 Full documentation <https://www.gnu.org/software/findutils/xargs>
 or available locally via: info xargs
 XARGS(1)