xargs Command
  
  
  Purpose
  
  Constructs parameter lists and runs commands.
  
   Syntax
  
  xargs [  -p ] [  -t ] [  -n Number] [  -l [ Number ] ] [  -x ]
  [   -e[ EndOfFile ] ] [   -i[ String ] ] [  -xSize ] [ 
  CommandLine ]
  
  Description
  
  The xargs command runs a command line.  It constructs the command
  line by combining the CommandLine parameter, a string containing
  a command and its flags or parameters, with additional parameters
  read from standard input.  It constructs the command line as many
  times as necessary to process  all input parameters.  The default
  CommandLine parameter is the echo command.
  
  Parameters read from standard input are character strings delim-
  ited  by  one  or more spaces, tabs, or new-line characters.  You
  can embed a space or a tab in parameters by preceding  it  with a
  \ (backslash) or by putting it in quotation marks. The xargs
  command reads characters enclosed in single  or  double quotation
  marks as literals and removes the delimiting quotation marks.  It
  always discards empty lines.
  
  The xargs command evaluates the size of the current environment
  when  determining  how  many arguments to add to the commands  it
  generates.   The size of the current environment plus the size of
  the command line generated by the xargs command cannot exceed the
  ARG_MAX value in length (see the  E2BIG error in the  execvp sub-
  routine).  The xargs command ends if both this limit is reached
  and the -x flag is used.  If the -x flag is not used, the xargs
  command uses as many arguments as will fit within the ARG_MAX
  limit on the first pass,  and  then makes successive passes using
  any remaining arguments until all specified  arguments  have been
  used.
  
  Note:	The xargs command ends if it cannot run the CommandLine
  parameter or if it receives a return code of -1.  When the Com-
  mandLine  parameter  calls  a shell procedure, the shell
  procedure should explicitly exit with an appropriate value to
  avoid accidentally returning a value of -1.
  
  Flags
  
  -e[EndOfFile]	Sets the logical end-of-file string. The xargs
  command reads standard input until it encounters either an end-
  of-file  character  or  the  logical  EOF string.  If you do  not
  specify the -e flag, the default EndOfFile parameter is _ ( the
  underline character).  If you specify -e without the EndOfFile
  parameter, the xargs command interprets the underline character
  as a literal character rather than as an end-of-file marker.
  
  -i[String]	Takes an entire line as a single parameter and inserts
  it in each instance of the String variable found in the
  CommandLine parameter.  A maximum of five parameters in the
  CommandLine parameter can each contain one or more instances of
  the String variable.  The xargs command discards spaces and tabs
  at the beginning of each line.  The command line constructed can-
  not be larger than 255 bytes.  The default String variable is { }
  (braces).  This flag also turns on the  -x flag.
  
  -l[Number]	Runs the CommandLine parameter with the specified
  number of nonempty parameter lines read from standard input.  The
  last invocation of the CommandLine parameter can have fewer
  parameter lines if fewer than  the  specified  number  remain.  A
  line ends with the first new-line character unless the last char-
  acter of the line is a space or a tab.  A trailing space  or  tab
  indicates a continuation through the next nonempty line.  The de-
  fault value of the Number variable is 1. This flag turns on the 
  -x flag.
  
  -nNumber	Runs the CommandLine parameter using as many standard
  input parameters  as possible, up to the maximum specified by the
  Number variable.The xargs command uses fewer parameters if their
  total size is greater than the number of bytes specified by the 
  -sSize flag.  It also uses fewer parameters for the last invoca-
  tion  if  fewer than the number of parameters  specified  by  the
  Number variable remain.  When the  -x flag is present, each
  Number variable must fit the size limitation specified by the -x
  flag.
  
  -p	Asks whether to run the CommandLine parameter.  It displays
  the constructed command line, followed by a ?...(question mark,
  dot dot dot) prompt.  Enter an affirmative  response  specific to
  the locale to run the CommandLine parameter.  Any other response
  causes the xargs command to skip that particular invocation of
  the parameter.  You are asked about each invocation.
  
  -sSize	Sets the maximum total size of each parameter list.  The
  Size variable must be a positive integer less than or equal to
  LINE_MAX.  The default size is LINE_MAX bytes.
  
  Note:	The byte count for the Size variable includes one extra
  byte for each parameter, plus the number of bytes in the  command
  name.
  
  -t	Echoes the CommandLine parameter and each constructed parame-
  ter list to standard error.
  
  -x	Stops running the xargs command if any parameter list is
  greater than the number of bytes specified by the  -s flag.  This
  flag is turned on if you specify either the  -i or  -l flag.  If
  you do not specify the -i, -l, or  -n flag, the total length of
  all parameters must be within the limit specified by the Size
  variable.
  
  Exit Status
  
  This command returns the following exit values:
  
  0	All invocations of the CommandLine parameter returned exit
  status 0
  
  1-125	Indicates one of the following errors:
  
  A command line meeting the specified requirements could not be
  assembled.
  
  One or more invocations of the CommandLine parameter returned a
  non-zero exit status.
  
  Some other error occurred.
  
  126	Found but could not invoke the command specified in the
  CommandLine parameter.
  
  127	Could not find the command specified in the CommandLine
  parameter.
  
  Examples
  
  1.	To use a command on files whose names are listed in a file,
  enter:
  
  xargs lint -a <cfiles1 *
  
  If cfiles contains the following text:
  
  main.c readit.c
  gettoken.c
  putobj.c
  
  the xargs command constructs and runs the following command:
  
  lint -a main.c readit.c gettoken.c putobj.c
  
  Each shell command line can be up to LINE-MAX bytes long.  If
  cfiles contains more file names than fit on a single line, the
  xargs command runs the lint command with the file names that fit.
  It then constructs and runs another lint command using the
  remaining file names.  Depending on the names listed in cfiles,
  the commands 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 fltdiv.c . . .
  
  This is not quite the same as running the lint command once with
  all the file names.  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
  command lines.
  
  For this reason you may want to run the command only if all the
  file names fit on one line.  Specify this to the xargs command by
  using the -x flag as follows:
  
  xargs -x lint -a <cfiles
  
  If all the file names in cfiles do not fit on one command line,
  the xargs command displays an error message.
  
  2.	To construct commands that contain a certain number of file
  names, enter:
  
  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 flag causes the xargs command to display each command be-
  fore running it, so you can see what is happening.  The <<end and
  end define a  here document, which uses the text entered before
  the end line as standard input for the xargs command.
  
  3.	To insert file names into the middle of command lines, enter:
  
  ls | xargs -t -i mv {} {}.old
  
  This renames all files in the current directory by adding .old to
  the end of each name.  The -i flag tells the xargs command to in-
  sert each line of the ls directory listing where { } (braces) ap-
  pear.  If the current directory contains the files chap1, chap2,
  and chap3, this constructs the following commands:
  
  mv chap1 chap1.old
  mv chap2 chap2.old
  mv chap3 chap3.old
  
  4.	To run a command on files that you select individually, enter:
  
  ls | xargs -p -n1 ar r lib.a
  
  This allows you to select files to add to the lib.a library. The
  -p flag tells the xargs command to display each ar command it
  constructs and to ask if you want to run it.  Enter y to run the
  command.  Press the Enter key if you do not want to run the com-
  mand.
  
  Implementation Specifics
  
  This command is part of Base Operating System (BOS) Runtime.
  
  Files
  
  /usr/bin/xargs	Contains the xargs command.
  
  Related Information
  
   Shells Overview in AIX Version 3.2 System User's Guide: Base and
  Devices.
  
   Commands Overview in AIX Version 3.2 System User's Guide: Base
  and Devices.
  
   Input and Output Handling Programmer's Overview in AIX Version
  3.2 General Programming Concepts.
  
  The  ar command,  diff command,  exit command,  lint command,  ls
  command,  mv command.