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xargs(1)							      xargs(1)

NAME
       xargs - Constructs argument lists and runs commands

SYNOPSIS
       xargs  [-e[eofstr]] [-E eofstr] [-i[replstr]] [-I replstr] [-l[number]]
       [-L number]  [-n[number]]  [-ptrx]  [-slength]  [CommandString]	[argu‐
       ment...]

       The  xargs  command  constructs	a  command line by combining a command
       string, containing a command and its options or arguments,  with	 addi‐
       tional arguments read from standard input.

STANDARDS
       Interfaces  documented on this reference page conform to industry stan‐
       dards as follows:

       xargs:  XCU5.0

       Refer to the standards(5) reference page	 for  more  information	 about
       industry standards and associated tags.

OPTIONS
       Sets  the logical end-of-file string to eofstr. The xargs command reads
       standard input until it encounters either an end-of-file	 character  or
       the logical end-of-file string.	If you do (underline).	If you specify
       -e with no eofstr, xargs interprets the underline character as  a  lit‐
       eral character, rather than as an end-of-file marker.  Specifies a log‐
       ical end-of-file string to replace the default underscore.   The	 xargs
       command	reads  standard input until either an end-of-file character or
       the logical end-of-file string is encountered.  Takes an entire line as
       a  single  argument and inserts it in each instance of replstr found in
       the command string.  A maximum of five arguments in the command	string
       can  each  contain one or more instances of replstr.  The xargs command
       discards spaces and tabs at the beginning of each line.	 The  argument
       constructed  cannot  be	larger than 255 bytes.	The default replstr is
       {}.  This option also turns on the -x option.  Insert mode: command  is
       executed for each line from standard input, taking the entire line as a
       single argument, inserting it  in  arguments  for  each	occurrence  of
       replstr.	 Any  blank  characters	 at  the  beginning  of	 each line are
       ignored. Constructed arguments  cannot  grow  larger  than  255	bytes.
       Option  -x  is forced on. The -I and -i options are mutually exclusive;
       the last one specified takes effect.  Runs the command string with  the
       specified  number  of nonempty argument lines read from standard input.
       The last invocation of the command string can have fewer argument lines
       if  fewer than number remain.  A line ends with the first newline char‐
       acter unless the last character of the line is a space  or  a  tab.   A
       trailing	 space	or  tab	 indicates  a  continuation  through  the next
       nonempty line. The default number is 1.	This option turns  on  the  -x
       option.	 The  command  is  executed for each non-empty number lines of
       argument from standard input. The last invocation of command has	 fewer
       lines  of argument if fewer than number remain. A line is considered to
       end with the first newline character unless the last character  of  the
       line is a blank character. A trailing blank character signals continua‐
       tion to the next non-empty line, inclusive.  The -L, -l and -n  options
       are  mutually  exclusive; the last one takes effect.  Executes the com‐
       mand string using as many standard input arguments as possible, up to a
       maximum	of  number.   The  xargs command uses fewer arguments if their
       total length is greater than the number of characters specified by  the
       -s  [length] option.  It also uses fewer arguments for the last invoca‐
       tion if fewer than number arguments remain.  When -x is	present,  each
       number  argument	 must fit the length limitation specified by -s.  Asks
       whether or not to run the command string.  It displays the  constructed
       command	line,  followed	 by  a ?...  prompt.  Press y, or the locale's
       equivalent of a y, to run  the  command	string.	  Any  other  response
       causes  xargs to skip that particular invocation of the command string.
       You are asked about each invocation.  Sets the maximum total length  of
       each  argument list. The length must be a positive integer less than or
       equal to 470.  The default length is 470 bytes.	Note that the  charac‐
       ter count for length includes one extra character for each argument and
       the number of characters in  the	 command  name.	  Echoes  the  command
       string and each constructed argument list to file descriptor 2 (usually
       standard error).	 Stops running xargs if any argument list  is  greater
       than  the number of characters specified by the -s length option.  This
       option is turned on if you specify either the -i or -l options.	If you
       do not specify -i, -l, or -n, the total length of all arguments must be
       within the length limit.

OPERANDS
       The name of the command to be invoked,  found  by  searching  the  path
       using  the PATH environment variable.  If CommandString is omitted, the
       default is the echo command.  An initial	 option	 or  operand  for  the
       invocation of CommandString.

DESCRIPTION
       The xargs command runs the command string as many times as necessary to
       process all input arguments.  The default command string is echo.

       Arguments read from standard input are character strings	 delimited  by
       one  or more spaces, tabs, or newline characters. You can embed a space
       or a tab in arguments by preceding it with a \ (backslash) or by	 quot‐
       ing  it.	 The xargs command reads characters enclosed in single or dou‐
       ble quotes as literals and removes the delimiting  quotes.   It	always
       discards empty lines.

       The  xargs  command  ends  if it cannot run the command string or if it
       receives an exit code of -1.  When the command  string  calls  a	 shell
       procedure, the shell procedure should explicitly exit with an appropri‐
       ate value to avoid accidentally returning -1.  (See the sh command.)

       The LC_MESSAGES variables determines the locale's equivalent of y and n
       (for yes/no queries).

EXIT STATUS
       The  following  exit  values  are returned: All invocations of Command‐
       String returned exit status zero.  A command line meeting the specified
       requirements  could not be assembled, one or more of the invocations of
       CommandString returned a non-zero exit  status,	or  some  other	 error
       occurred.   The	command specified by CommandString was found but could
       not be invoked.	The command specified by CommandString	could  not  be
       found.

EXAMPLES
       To  use a command on files whose names are listed in a file, use a com‐
       mand line similar to the following: xargs  lint	-a  < cfiles

	      If cfiles contains the text, enter: main.c  readit.c  gettoken.c
	      putobj.c

	      then  xargs  constructs  and  runs the command: lint  -a	main.c
	      readit.c	gettoken.c  putobj.c

	      Each shell command line can be up to 470 bytes long.  If	cfiles
	      contains	more file namess than fit on a single line, then xargs
	      runs the lint command with the file namess that  fit.   It  then
	      constructs  and  runs  another  lint command using the remaining
	      file namess.  Depending on the names listed in cfiles, the  com‐
	      mands might look like the following:

	      lint   -a	  main.c   readit.c  gettoken.c...  lint  -a  getisx.c
	      getprp.c	 getpid.c...   lint   -a   fltadd.c   fltmult.c	  flt‐
	      div.c...

	      This  is	not  quite  the same as running lint once with all the
	      file namess.  The lint command checks  cross-references  between
	      files.   However, in this example it cannot check between main.c
	      and fltadd.c, or between any two files listed on	separate  com‐
	      mand lines.

	      For  this	 reason	 you might want to run the command only if all
	      the file namess fit on one line. Do this by using xargs with the
	      -x option: xargs	-x  lint  -a  <cfiles

	      If  all the file names in cfiles do not fit on one command line,
	      then xargs displays an error  message.   To  construct  commands
	      that contain a certain number of file namess, use a command line
	      similar to the following: xargs  -t  -n2	diff   <<end  starting
	      chap1  concepts  chap2  writing chap3 end

	      This  constructs	and  runs  diff commands that contain two file
	      names each (-n2):

	      diff  starting  chap1 diff  concepts  chap2 diff	writing	 chap3

	      The -t option tells xargs to display each command before running
	      it  so  that  you	 can see what is happening.  The <<end and end
	      arguments define a Here Document, which uses  the	 text  entered
	      before  the  end	line  as standard input for the xargs command.
	      (For more details, see the section Inline Input (Here) Documents
	      in  the  sh(1)  reference page.)	To insert file namess into the
	      middle of commands, use a command line similar to the following:
	      ls  |  xargs  -t	-i  mv	{}  {}.old

	      This renames all files in the current directory by adding to the
	      end of each name.	 The -i tells xargs to insert each line of the
	      ls  directory listing where { } (braces) appear.	If the current
	      directory contains the files chap1, chap2, and chap3, then  this
	      constructs the following commands:

	      mv   chap1   chap1.old mv	 chap2	chap2.old mv  chap3  chap3.old
	      To run a command on files that you select	 individually,	use  a
	      command line similar to the following: ls	 |  xargs  -p  -n1  ar
	      r	 lib.a

	      This allows you to select files to add  to  the  library	lib.a.
	      The  -p  option  tells  xargs to display each ar command it con‐
	      structs and ask if you want to run it.  Press y, or the locale's
	      equivalent of a y, and press <Return> to run the command.	 Press
	      <Return> alone if you do not want to run it.

ENVIRONMENT VARIABLES
       The following environment variables affect the execution of xargs: Pro‐
       vides  a	 default value for the internationalization variables that are
       unset or null. If LANG is unset or null, the corresponding  value  from
       the  default  locale is used.  If any of the internationalization vari‐
       ables contain an invalid setting, the utility behaves as if none of the
       variables  had been defined.  If set to a non-empty string value, over‐
       rides the values	 of  all  the  other  internationalization  variables.
       Determines  the	locale for the interpretation of sequences of bytes of
       text data as characters (for example, single-byte as opposed to	multi‐
       byte characters in arguments and input files) and the behavior of char‐
       acter classes used for yesexprlocal keyword in  the  LC_MESSAGES	 cate‐
       gory.   Determines the locale for the format and contents of diagnostic
       messages written to standard error.  Determines the location of message
       catalogues  for the processing of LC_MESSAGES.  Determines the location
       of CommandString.

SEE ALSO
       Commands:  ksh(1), Bourne shell sh(1b), POSIX shell sh(1p)

       Standards:  standards(5)

								      xargs(1)
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