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XARGS(1)		FreeBSD	General	Commands Manual		      XARGS(1)

NAME
     xargs -- construct	argument list(s) and execute utility

SYNOPSIS
     xargs [-0oprt] [-E	eofstr]	[-I replstr [-R	replacements] [-S replsize]]
	   [-J replstr]	[-L number] [-n	number [-x]] [-P maxprocs] [-s size]
	   [utility [argument ...]]

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

     Any arguments specified on	the command line are given to utility upon
     each invocation, followed by some number of the arguments read from the
     standard input of xargs.  This is repeated	until standard input is
     exhausted.

     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 charac-
     ters, 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	(``\0'') 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	occur-
	     rences 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 replsize (or 255 if	no -S flag is speci-
	     fied) bytes; this is implemented by concatenating as much of the
	     argument containing replstr as possible, to the constructed argu-
	     ments to utility, up to replsize bytes.  The size 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 affect 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 dis-
	     tinct 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 lines read.	If EOF is reached and
	     fewer lines have been read	than number 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
	     5000.

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

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

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

     -r	     Compatibility with	GNU xargs.  The	GNU version of xargs runs the
	     utility argument at least once, even if xargs input is empty, and
	     it	supports a -r option to	inhibit	this behavior.	The FreeBSD
	     version of	xargs does not run the utility argument	on empty
	     input, but	it supports the	-r option for command-line compatibil-
	     ity with GNU xargs, but the -r option does	nothing	in the FreeBSD
	     version of	xargs.

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

     -S	replsize
	     Specify the amount	of space (in bytes) that -I can	use for
	     replacements.  The	default	for replsize is	255.

     -s	size
	     Set the maximum number of bytes for the command line length pro-
	     vided to utility.	The sum	of the length of the utility name, the
	     arguments passed to utility (including NULL terminators) and the
	     current environment will be less than or equal to this number.
	     The current default value for size	is ARG_MAX - 4096.

     -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) com-
	     mand line length.

     If	utility	is omitted, echo(1) is used.

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

     If	a command line cannot be assembled, or cannot be invoked, or if	an
     invocation	of utility is terminated by a signal, or an invocation of
     utility exits with	a value	of 255,	the xargs utility stops	processing
     input and exits after all invocations of utility finish processing.

EXIT STATUS
     The xargs utility exits with a value of 0 if no error occurs.  If utility
     cannot be found, xargs exits with a value of 127, otherwise if utility
     cannot be executed, xargs exits with a value of 126.  If any other	error
     occurs, xargs exits with a	value of 1.

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

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

HISTORY
     The xargs utility appeared	in PWB UNIX.

BUGS
     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.

     The xargs utility does not	take multibyte characters into account when
     performing	string comparisons for the -I and -J options, which may	lead
     to	incorrect results in some locales.

FreeBSD	10.1			March 16, 2012			  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | EXIT STATUS | SEE ALSO | STANDARDS | HISTORY | BUGS

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