Provided by: findutils_4.6.0+git+20160126-2_amd64 bug


       xargs - build and execute command lines from standard input


       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]
       [--process-slot-var=name]   [--interactive]   [--verbose]   [--exit]   [--no-run-if-empty]
       [--arg-file=file] [--show-limits] [--version] [--help] [command [initial-arguments]]


       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-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 stderr when this


       -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.   Otherwise, stdin is redirected from

       --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.

       -e[eof-str], --eof[=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.

       -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 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.

              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 ouptut 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).

       -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

       -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 128KiB, 128Kib is used as the default  value;
              otherwise,  the  default  value  is  the  maximum.   1KiB  is  1024  bytes.   xargs
              automatically adapts to tighter constraints.

              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

       -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.

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

              Print the version number of xargs and exit.


       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

       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 input.  This example achieves the same effect as BSD's -o
       option, but in a more flexible and portable way.


       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.


       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,

       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.


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

       The  full documentation for xargs is maintained as a Texinfo  manual.   If  the  info  and
       xargs programs are properly installed at your site, the command info xargs should give you
       access to the complete manual.


       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  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

       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 invocation 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   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