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NAME    [Toc]    [Back]

     xargs - construct argument list(s) and execute utility

SYNOPSIS    [Toc]    [Back]

     xargs [-0opt] [-E eofstr] [-I replstr [-R replacements]] [-J
           [-L number] [-n number [-x]] [-P maxjobs] [-s size]
           [utility [argument ...]]

DESCRIPTION    [Toc]    [Back]

     The xargs utility reads space, tab, newline, and end-of-file
     strings from the standard input and executes  the  specified
utility with
     the strings as arguments.

     Any arguments specified on the command line are given to the
utility upon
     each invocation, followed by some number  of  the  arguments
read from standard
  input.  The utility is repeatedly executed until standard input is

     Spaces, tabs and newlines may be embedded in arguments using
single (`'')
     or  double  (`"') quotes or backslashes (`').  Single quotes
escape all
     non-single quote characters, excluding newlines, up  to  the
matching single
  quote.  Double quotes escape all non-double quote characters, excluding
 newlines, up to the matching double quote.   Any  single
character, including
 newlines, may be escaped by a backslash.

     The options are as follows:

     -0      Change xargs to expect NUL (` ') characters as separators, instead
 of spaces and newlines.  This is  expected  to
be used in
             concert with the -print0 function in find(1).

     -E eofstr
             Use eofstr as a logical EOF marker.

     -I replstr
             Execute  utility  for each input line, replacing one
or more occurrences
 of replstr in up to replacements (or 5 if  no
-R flag is
             specified) arguments to utility with the entire line
of input.
             The resulting arguments, after replacement is  done,
will not be
             allowed to grow beyond 255 bytes; this is implemented by concatenating
 as much of the argument containing replstr as
possible, to
             the  constructed  arguments  to  utility,  up to 255
bytes.  The 255
             byte limit does not apply to  arguments  to  utility
which do not
             contain  replstr,  and  furthermore,  no replacement
will be done on
             utility itself.  Implies -x.

     -J replstr
             If this option is specified, xargs will use the data
read from
             standard  input  to  replace the first occurrence of
replstr instead
             of appending that data after  all  other  arguments.
This option
             will not effect how many arguments will be read from
input (-n),
             or the size of the command(s)  xargs  will  generate
(-s).  The option
 just moves where those arguments will be placed
in the command(s)
 that are executed.  The replstr must show up
as a distinct
  argument to xargs.  It will not be recognized
if, for instance,
 it is in the  middle  of  a  quoted  string.
Furthermore, only
  the  first occurrence of the replstr will be replaced.  For example,
 the following command will copy the  list  of
files and directories
  which  start  with an uppercase letter in
the current directory
 to destdir:

                   /bin/ls -1d [A-Z]* | xargs -J % cp -rp % destdir

     -L number
             Call utility for every number of lines read.  If EOF
is reached
             and fewer than number  lines  have  been  read  then
utility will be
             called with the available lines.

     -n number
             Set the maximum number of arguments taken from standard input for
             each  invocation  of  utility.   An  invocation   of
utility will use
             less  than  number  standard  input arguments if the
number of bytes
             accumulated (see the -s option) exceeds  the  specified size or
             there  are fewer than number arguments remaining for
the last invocation
 of utility.  The current default value  for
number is

     -o      Reopen stdin as /dev/tty in the child process before
             the command.  This is useful if you  want  xargs  to
run an interactive

     -P maxprocs
             Parallel  mode:  run at most maxprocs invocations of
utility at

     -p      Echo each command to be executed and  ask  the  user
whether it
             should be executed.  An affirmative response, `y' in
             locale, causes the command to be executed, any other
             causes  it  to be skipped.  No commands are executed
if the process
             is not attached to a terminal.

     -R replacements
             Specify the maximum number of arguments that -I will
do replacement
 in.  If replacements is negative, the number of
arguments in
             which to replace is unbounded.

     -s size
             Set the maximum number of bytes for the command line
length provided
  to  utility.   The  sum  of the length of the
utility name, the
             arguments passed to utility (including NUL  terminators) and the
             current  environment  will  be less than or equal to
this number.
             The current default value  for  size  is  ARG_MAX  -

     -t       Echo  the  command to be executed to standard error
immediately before
 it is executed.

     -x      Force xargs to terminate immediately  if  a  command
line containing
             number  arguments  will not fit in the specified (or
default) command
 line length.

     If no utility is specified, echo(1) is used.

     Undefined behavior may occur if utility reads from the standard input.

     The  xargs utility exits immediately (without processing any
further input)
 if a command line cannot be assembled,  utility  cannot
be invoked, an
     invocation of utility is terminated by a signal, or an invocation of
     utility exits with a value of 255.

DIAGNOSTICS    [Toc]    [Back]

     xargs exits with one of the following values:

     0       All invocations of utility returned a zero exit status.
     123     One or more invocations of utility returned a nonzero exit status.

     124     The utility exited with a 255 exit status.
     125     The utility was killed or stopped by a signal.
     126     The utility was found but could not be executed.
     127     The utility could not be found.
     1       Some other error occurred.

SEE ALSO    [Toc]    [Back]

     echo(1), find(1), execvp(3)

STANDARDS    [Toc]    [Back]

     The  xargs  utility  is  expected  to  be  IEEE  Std  1003.2
(``POSIX.2'') compliant.
   The -J, -o, -P and -R options are non-standard extensions which may
     not be available on other operating systems.

     The meanings of the 123, 124, and 125 exit values were taken
from GNU

HISTORY    [Toc]    [Back]

     The xargs command appeared in PWB UNIX.

BUGS    [Toc]    [Back]

     If  utility attempts to invoke another command such that the
number of arguments
 or the size of  the  environment  is  increased,  it
risks execvp(3)
     failing with E2BIG.

OpenBSD      3.6                            May      7,      2001
[ Back ]
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