a502340a03
PR: docs/106416 Submitted by: Pete Slagle, freebsd-stable at voidcaptain.com MFC after: 3 days
366 lines
8.9 KiB
Groff
366 lines
8.9 KiB
Groff
.\" Copyright (c) 1990, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" John B. Roll Jr. and the Institute of Electrical and Electronics
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.\" Engineers, Inc.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)xargs.1 8.1 (Berkeley) 6/6/93
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.\" $FreeBSD$
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.\" $xMach: xargs.1,v 1.2 2002/02/23 05:23:37 tim Exp $
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.\"
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.Dd January 26, 2008
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.Dt XARGS 1
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.Os
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.Sh NAME
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.Nm xargs
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.Nd "construct argument list(s) and execute utility"
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.Sh SYNOPSIS
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.Nm
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.Op Fl 0r
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.Op Fl E Ar eofstr
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.Oo
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.Fl I Ar replstr
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.Op Fl R Ar replacements
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.Op Fl S Ar replsize
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.Oc
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.Op Fl J Ar replstr
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.Op Fl L Ar number
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.Oo
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.Fl n Ar number
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.Op Fl x
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.Oc
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.Op Fl P Ar maxprocs
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.Op Fl s Ar size
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.Op Ar utility Op Ar argument ...
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.Sh DESCRIPTION
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The
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.Nm
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utility reads space, tab, newline and end-of-file delimited strings
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from the standard input and executes
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.Ar utility
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with the strings as
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arguments.
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.Pp
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Any arguments specified on the command line are given to
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.Ar utility
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upon each invocation, followed by some number of the arguments read
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from the standard input of
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.Nm .
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This is repeated until standard input is exhausted.
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.Pp
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Spaces, tabs and newlines may be embedded in arguments using single
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(``\ '\ '')
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or double (``"'') quotes or backslashes (``\e'').
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Single quotes escape all non-single quote characters, excluding newlines,
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up to the matching single quote.
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Double quotes escape all non-double quote characters, excluding newlines,
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up to the matching double quote.
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Any single character, including newlines, may be escaped by a backslash.
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.Pp
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The options are as follows:
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.Bl -tag -width indent
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.It Fl 0
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Change
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.Nm
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to expect NUL
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(``\\0'')
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characters as separators, instead of spaces and newlines.
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This is expected to be used in concert with the
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.Fl print0
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function in
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.Xr find 1 .
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.It Fl E Ar eofstr
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Use
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.Ar eofstr
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as a logical EOF marker.
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.It Fl I Ar replstr
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Execute
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.Ar utility
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for each input line, replacing one or more occurrences of
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.Ar replstr
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in up to
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.Ar replacements
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(or 5 if no
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.Fl R
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flag is specified) arguments to
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.Ar utility
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with the entire line of input.
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The resulting arguments, after replacement is done, will not be allowed to grow
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beyond
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.Ar replsize
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(or 255 if no
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.Fl S
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flag is specified)
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bytes; this is implemented by concatenating as much of the argument
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containing
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.Ar replstr
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as possible, to the constructed arguments to
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.Ar utility ,
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up to
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.Ar replsize
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bytes.
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The size limit does not apply to arguments to
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.Ar utility
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which do not contain
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.Ar replstr ,
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and furthermore, no replacement will be done on
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.Ar utility
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itself.
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Implies
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.Fl x .
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.It Fl J Ar replstr
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If this option is specified,
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.Nm
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will use the data read from standard input to replace the first occurrence of
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.Ar replstr
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instead of appending that data after all other arguments.
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This option will not affect how many arguments will be read from input
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.Pq Fl n ,
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or the size of the command(s)
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.Nm
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will generate
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.Pq Fl s .
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The option just moves where those arguments will be placed in the command(s)
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that are executed.
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The
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.Ar replstr
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must show up as a distinct
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.Ar argument
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to
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.Nm .
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It will not be recognized if, for instance, it is in the middle of a
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quoted string.
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Furthermore, only the first occurrence of the
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.Ar replstr
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will be replaced.
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For example, the following command will copy the list of files and
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directories which start with an uppercase letter in the current
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directory to
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.Pa destdir :
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.Pp
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.Dl /bin/ls -1d [A-Z]* | xargs -J % cp -rp % destdir
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.Pp
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.It Fl L Ar number
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Call
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.Ar utility
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for every
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.Ar number
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lines read.
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If EOF is reached and fewer lines have been read than
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.Ar number
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then
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.Ar utility
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will be called with the available lines.
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.It Fl n Ar number
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Set the maximum number of arguments taken from standard input for each
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invocation of
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.Ar utility .
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An invocation of
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.Ar utility
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will use less than
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.Ar number
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standard input arguments if the number of bytes accumulated (see the
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.Fl s
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option) exceeds the specified
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.Ar size
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or there are fewer than
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.Ar number
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arguments remaining for the last invocation of
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.Ar utility .
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The current default value for
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.Ar number
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is 5000.
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.It Fl o
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Reopen stdin as
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.Pa /dev/tty
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in the child process before executing the command.
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This is useful if you want
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.Nm
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to run an interactive application.
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.It Fl P Ar maxprocs
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Parallel mode: run at most
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.Ar maxprocs
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invocations of
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.Ar utility
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at once.
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.It Fl p
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Echo each command to be executed and ask the user whether it should be
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executed.
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An affirmative response,
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.Ql y
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in the POSIX locale,
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causes the command to be executed, any other response causes it to be
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skipped.
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No commands are executed if the process is not attached to a terminal.
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.It Fl r
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Compatibility with GNU
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.Nm .
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The GNU version of
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.Nm
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runs the
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.Ar utility
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argument at least once, even if
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.Nm
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input is empty, and it supports a
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.Fl r
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option to inhibit this behavior.
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The
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.Fx
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version of
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.Nm
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does not run the
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.Ar utility
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argument on empty input, but it supports the
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.Fl r
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option for command-line compatibility with GNU
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.Nm ,
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but the
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.Fl r
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option does nothing in the
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.Fx
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version of
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.Nm .
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.It Fl R Ar replacements
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Specify the maximum number of arguments that
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.Fl I
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will do replacement in.
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If
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.Ar replacements
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is negative, the number of arguments in which to replace is unbounded.
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.It Fl S Ar replsize
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Specify the amount of space (in bytes) that
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.Fl I
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can use for replacements.
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The default for
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.Ar replsize
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is 255.
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.It Fl s Ar size
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Set the maximum number of bytes for the command line length provided to
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.Ar utility .
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The sum of the length of the utility name, the arguments passed to
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.Ar utility
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(including
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.Dv NULL
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terminators) and the current environment will be less than or equal to
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this number.
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The current default value for
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.Ar size
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is
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.Dv ARG_MAX
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- 4096.
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.It Fl t
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Echo the command to be executed to standard error immediately before it
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is executed.
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.It Fl x
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Force
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.Nm
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to terminate immediately if a command line containing
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.Ar number
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arguments will not fit in the specified (or default) command line length.
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.El
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.Pp
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If
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.Ar utility
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is omitted,
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.Xr echo 1
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is used.
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.Pp
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Undefined behavior may occur if
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.Ar utility
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reads from the standard input.
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.Pp
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The
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.Nm
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utility exits immediately (without processing any further input) if a
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command line cannot be assembled,
|
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.Ar utility
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cannot be invoked, an invocation of
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.Ar utility
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is terminated by a signal,
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or an invocation of
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.Ar utility
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exits with a value of 255.
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.Sh EXIT STATUS
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The
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.Nm
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utility exits with a value of 0 if no error occurs.
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If
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.Ar utility
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cannot be found,
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.Nm
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exits with a value of 127, otherwise if
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.Ar utility
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cannot be executed,
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.Nm
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exits with a value of 126.
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If any other error occurs,
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.Nm
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exits with a value of 1.
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.Sh SEE ALSO
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.Xr echo 1 ,
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.Xr find 1 ,
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.Xr execvp 3
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.Sh STANDARDS
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The
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.Nm
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utility is expected to be
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.St -p1003.2
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compliant.
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The
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.Fl J , o , P, R
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and
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.Fl S
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options are non-standard
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.Fx
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extensions which may not be available on other operating systems.
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.Sh HISTORY
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The
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.Nm
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utility appeared in PWB UNIX.
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.Sh BUGS
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If
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.Ar utility
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attempts to invoke another command such that the number of arguments or the
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size of the environment is increased, it risks
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.Xr execvp 3
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failing with
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.Er E2BIG .
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.Pp
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The
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.Nm
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utility does not take multibyte characters into account when performing
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string comparisons for the
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.Fl I
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and
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.Fl J
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options, which may lead to incorrect results in some locales.
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