XARGS(1)														  XARGS(1)



NAME
       xargs - build and execute command lines from standard input

SYNOPSIS
       xargs  [-0prtx]	[-E  eof-str] [-e[eof-str]] [--eof[=eof-str]] [--null] [-d delimiter] [--delimiter delimiter] [-I replace-
       str] [-i[replace-str]] [--replace[=replace-str]] [-l[max-lines]] [-L  max-lines]  [--max-lines[=max-lines]]  [-n  max-args]
       [--max-args=max-args]   [-s  max-chars]	[--max-chars=max-chars]  [-P  max-procs]  [--max-procs=max-procs]  [--interactive]
       [--verbose]  [--exit]  [--no-run-if-empty]  [--arg-file=file]  [--show-limits]  [--version]  [--help]  [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.

       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 stderr when this happens.

OPTIONS
       --arg-file=file
       -a 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.

       --null
       -0     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 -print0  option
	      produces input suitable for this mode.


       --delimiter=delim
       -d delim
	      Input items are terminated by the specified character.  Quotes and backslash are not special; every character in the
	      input is taken literally.  Disables the end-of-file string, which is treated like any other argument.  This  can	be
	      used  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.  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.


       -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.

       --eof[=eof-str]
       -e[eof-str]
	      This option is a synonym for the -E option.  Use -E instead, 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.

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

       -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.

       --replace[=replace-str]
       -i[replace-str]
	      This option is a synonym for -Ireplace-str if replace-str is specified, and for -I{} otherwise.  This option is dep‐
	      recated; 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.

       --max-lines[=max-lines]
       -l[max-lines]
	      Synonym  for  the  -L option.  Unlike -L, the max-lines argument 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.

       --max-args=max-args
       -n 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.

       --interactive
       -p     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.

       --no-run-if-empty
       -r     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.

       --max-chars=max-chars
       -s 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 128KiB, 128Kib is used as the default value; otherwise, the default value is the maximum.   1KiB  is  1024
	      bytes.

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

       --version
	      Print the version number of xargs and exit.

       --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.

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

       --max-procs=max-procs
       -P 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 with -P; otherwise chances are that only one exec will be done.

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 di‐
       rectory 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.


       xargs sh -c 'emacs "$@" < /dev/tty' emacs

       Launches the minimum number of copies of Emacs needed, one after the other, to edit the files listed on xargs' standard in‐
       put.  This example achieves the same effect as BSD's -o option, but in a more flexible and portable way.




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 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 stan‐
       dard.  Therefore you should use -L and -I instead, respectively.

       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.



SEE ALSO
       find(1), locate(1), locatedb(5), updatedb(1), fork(2), execvp(3), Finding Files (on-line in Info, or printed)

BUGS
       The -L option is incompatible with the -I option, but perhaps should not be.

       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 manipu‐
       late  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	Considera‐
       tions'' chapter in the findutils Texinfo documentation.	The -execdir option of find can often be used as a more secure al‐
       ternative.

       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 because it doesn't use the -i option.  The second invo‐
       cation of xargs does have such a limit, but we have ensured that the 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.

       The  best  way to report a bug is to use the form at http://savannah.gnu.org/bugs/?group=findutils.  The reason for this is
       that you will then be able to track progress in fixing the problem.   Other comments about xargs(1) and about the findutils
       package	in  general  can  be  sent  to	the bug-findutils mailing list.  To join the list, send email to bug-findutils-re‐
       quest@gnu.org.



															  XARGS(1)