Provided by: findutils_4.4.2-4ubuntu1_amd64 bug

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  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.

       --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 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.

       -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 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.

       --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 defaults 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 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.

       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.

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  standard.   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  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 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
       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-request@gnu.org.

                                                                                         XARGS(1)