.\"	$NetBSD: xargs.1,v 1.10 1999/12/22 14:41:00 kleink Exp $
.\"
.\" Copyright (c) 1990, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" John B. Roll Jr. and the Institute of Electrical and Electronics
.\" Engineers, Inc.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\"
.\"	@(#)xargs.1	8.1 (Berkeley) 6/6/93
.\"
.Dd December 21, 1999
.Dt XARGS 1
.Os
.Sh NAME
.Nm xargs
.Nd "construct argument list(s) and execute utility"
.Sh SYNOPSIS
.Nm
.Op Fl 0
.Op Fl p
.Op Fl t
.Oo Op Fl x
.Fl n Ar number
.Oc
.Op Fl s Ar size
.Op Ar utility Op Ar arguments ...
.Sh DESCRIPTION
The
.Nm
utility reads space, tab, newline and end-of-file delimited arguments
from the standard input and executes the specified
.Ar utility
with them as
arguments.
.Pp
The utility and any arguments specified on the command line are given
to the
.Ar utility
upon each invocation, followed by some number of the arguments read
from standard input.
The
.Ar utility
is repeatedly executed until standard input is exhausted.
.Pp
Spaces, tabs and newlines may be embedded in arguments using single
(``\ '\ '')
or double (``"'') quotes or backslashes (``\e'').
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.
.Pp
The options are as follows:
.Bl -tag -width Fl
.It Fl 0
Use NUL
(``\e0'')
instead of whitespace as the argument separator.
This can be used in conjuction with the
.Fl print0
option of
.Xr find 1 .
.It Fl n Ar number
Set the maximum number of arguments taken from standard input for each
invocation of the utility.
An invocation of
.Ar utility
will use less than
.Ar number
standard input arguments if the number of bytes accumulated (see the
.Fl s
option) exceeds the specified
.Ar size
or there are fewer than
.Ar number
arguments remaining for the last invocation of
.Ar utility .
The current default value for
.Ar number
is 5000.
.It Fl p
Prompt mode: immediately before each command execution the user is prompted
whether to execute the command instance.  If an affirmative response is read
from
.Pa /dev/tty
the command will be executed; otherwise this particular invocation will be
skipped.
This option implies the
.Fl t
option.
.It Fl s Ar size
Set the maximum number of bytes for the command line length provided to
.Ar utility .
The sum of the length of the utility name and the arguments passed to
.Ar utility
(including
.Dv NULL
terminators) will be less than or equal to this number.
The current default value for
.Ar size
is
.Dv ARG_MAX
- 2048.
.It Fl t
Echo the command to be executed to standard error immediately before it
is executed.
.It Fl x
Force
.Nm
to terminate immediately if a command line containing
.Ar number
arguments will not fit in the specified (or default) command line length.
.El
.Pp
If no
.Ar utility
is specified,
.Xr echo 1
is used.
.Pp
Undefined behavior may occur if
.Ar utility
reads from the standard input.
.Pp
The
.Nm
utility exits immediately (without processing any further input) if a
command line cannot be assembled,
.Ar utility
cannot be invoked, an invocation of the utility is terminated by a signal
or an invocation of the utility exits with a value of 255.
.Sh FILES
.Bl -tag -width /dev/tty -compact
.It Pa /dev/tty
used to read responses in prompt mode
.El
.Sh DIAGNOSTICS
.Nm
exits with one of the following values:
.Bl -tag -width Ds -compact
.It 0
All invocations of
.Ar utility
returned a zero exit status.
.It 123
One or more invocations of
.Ar utility
returned a nonzero exit status.
.It 124
The
.Ar utility
exited with a 255 exit status.
.It 125
The
.Ar utility
was killed or stopped by a signal.
.It 126
The
.Ar utility
was found but could not be invoked.
.It 127
The
.Ar utility
could not be found.
.It 1
Some other error occurred.
.El
.Sh SEE ALSO
.Xr echo 1 ,
.Xr find 1
.Sh STANDARDS
The
.Nm
utility is expected to be
.St -p1003.2
compliant.
.Sh HISTORY
The
.Nm xargs
command appeared in PWB Unix 1.0.
It made its first BSD appearance in the 4.3 Reno release.
.Pp
The meaning of 123, 124, and 125 exit values and the
.Fl 0
option were taken from GNU xargs.