xargs/xargs.1

   1 .\" Copyright (c) 1990, 1991, 1993
   2 .\"     The Regents of the University of California.  All rights reserved.
   3 .\"
   4 .\" This code is derived from software contributed to Berkeley by
   5 .\" John B. Roll Jr. and the Institute of Electrical and Electronics
   6 .\" Engineers, Inc.
   7 .\"
   8 .\" Redistribution and use in source and binary forms, with or without
   9 .\" modification, are permitted provided that the following conditions
  10 .\" are met:
  11 .\" 1. Redistributions of source code must retain the above copyright
  12 .\"    notice, this list of conditions and the following disclaimer.
  13 .\" 2. Redistributions in binary form must reproduce the above copyright
  14 .\"    notice, this list of conditions and the following disclaimer in the
  15 .\"    documentation and/or other materials provided with the distribution.
  16 .\" 3. All advertising materials mentioning features or use of this software
  17 .\"    must display the following acknowledgement:
  18 .\"     This product includes software developed by the University of
  19 .\"     California, Berkeley and its contributors.
  20 .\" 4. Neither the name of the University nor the names of its contributors
  21 .\"    may be used to endorse or promote products derived from this software
  22 .\"    without specific prior written permission.
  23 .\"
  24 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27 .\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34 .\" SUCH DAMAGE.
  35 .\"
  36 .\"     @(#)xargs.1     8.1 (Berkeley) 6/6/93
  37 .\" $FreeBSD: src/usr.bin/xargs/xargs.1,v 1.23 2002/06/22 12:47:56 jmallett Exp $
  38 .\" $xMach: xargs.1,v 1.2 2002/02/23 05:23:37 tim Exp $
  39 .\"
  40 .Dd May 7, 2001
  41 .Dt XARGS 1
  42 .Os
  43 .Sh NAME
  44 .Nm xargs
  45 .Nd "construct argument list(s) and execute utility"
  46 .Sh SYNOPSIS
  47 .Nm
  48 .Op Fl 0pt
  49 .Op Fl E Ar eofstr
  50 .Oo
  51 .Fl I Ar replstr
  52 .Op Fl R Ar replacements
  53 .Oc
  54 .Op Fl J Ar replstr
  55 .Op Fl L Ar number
  56 .Oo
  57 .Fl n Ar number
  58 .Op Fl x
  59 .Oc
  60 .Op Fl s Ar size
  61 .Op Ar utility Op Ar argument ...
  62 .Sh DESCRIPTION
  63 The
  64 .Nm
  65 utility reads space, tab, newline and end-of-file delimited arguments
  66 from the standard input and executes the specified
  67 .Ar utility
  68 with them as
  69 arguments.
  70 .Pp
  71 The utility and any arguments specified on the command line are given
  72 to the
  73 .Ar utility
  74 upon each invocation, followed by some number of the arguments read
  75 from standard input.
  76 The
  77 .Ar utility
  78 is repeatedly executed until standard input is exhausted.
  79 .Pp
  80 Spaces, tabs and newlines may be embedded in arguments using single
  81 (``\ '\ '')
  82 or double (``"'') quotes or backslashes (``\e'').
  83 Single quotes escape all non-single quote characters, excluding newlines,
  84 up to the matching single quote.
  85 Double quotes escape all non-double quote characters, excluding newlines,
  86 up to the matching double quote.
  87 Any single character, including newlines, may be escaped by a backslash.
  88 .Pp
  89 The options are as follows:
  90 .Bl -tag -width indent
  91 .It Fl 0
  92 Change
  93 .Nm
  94 to expect NUL
  95 (``\\0'')
  96 characters as separators, instead of spaces and newlines.
  97 This is expected to be used in concert with the
  98 .Fl print0
  99 function in
 100 .Xr find 1 .
 101 .It Fl E Ar eofstr
 102 Use
 103 .Ar eofstr
 104 as a logical EOF marker.
 105 .It Fl I Ar replstr
 106 Execute
 107 .Ar utility
 108 for each input line, replacing one or more occurences of
 109 .Ar replstr
 110 in up to
 111 .Ar replacements
 112 (or 5 if no
 113 .Fl R
 114 flag is specified) arguments to
 115 .Ar utility
 116 with the entire line of input.
 117 The resulting arguments, after replacement is done, will not be allowed to grow
 118 beyond 255 bytes; this is implemented by concatenating as much of the argument
 119 containing
 120 .Ar replstr
 121 as possible, to the constructed arguments to
 122 .Ar utility ,
 123 up to 255 bytes.
 124 The 255 byte limit does not apply to arguments to
 125 .Ar utility
 126 which do not contain
 127 .Ar replstr ,
 128 and furthermore, no replacement will be done on
 129 .Ar utility
 130 itself.
 131 Implies
 132 .Fl x .
 133 .It Fl J Ar replstr
 134 If this option is specified,
 135 .Nm
 136 will use the data read from standard input to replace the first occurrence of
 137 .Ar replstr
 138 instead of appending that data after all other arguments.
 139 This option will not effect how many arguments will be read from input
 140 .Pq Fl n ,
 141 or the size of the command(s)
 142 .Nm
 143 will generate
 144 .Pq Fl s .
 145 The option just moves where those arguments will be placed in the command(s)
 146 that are executed.
 147 The
 148 .Ar replstr
 149 must show up as a distinct
 150 .Ar argument
 151 to
 152 .Nm .
 153 It will not be recognized if, for instance, it is in the middle of a
 154 quoted string.
 155 Furthermore, only the first occurrence of the
 156 .Ar replstr
 157 will be replaced.
 158 For example, the following command will copy the list of files and
 159 directories which start with an uppercase letter in the current
 160 directory to
 161 .Pa destdir :
 162 .Pp
 163 .Dl /bin/ls -1d [A-Z]* | xargs -J % cp -rp % destdir
 164 .Pp
 165 .It Fl L Ar number
 166 Call
 167 .Ar utility
 168 for every
 169 .Ar number
 170 lines read.
 171 If EOF is reached and fewer lines have been read than
 172 .Ar number
 173 then
 174 .Ar utility
 175 will be called with the available lines.
 176 .It Fl n Ar number
 177 Set the maximum number of arguments taken from standard input for each
 178 invocation of the utility.
 179 An invocation of
 180 .Ar utility
 181 will use less than
 182 .Ar number
 183 standard input arguments if the number of bytes accumulated (see the
 184 .Fl s
 185 option) exceeds the specified
 186 .Ar size
 187 or there are fewer than
 188 .Ar number
 189 arguments remaining for the last invocation of
 190 .Ar utility .
 191 The current default value for
 192 .Ar number
 193 is 5000.
 194 .It Fl p
 195 Echo each command to be executed and ask the user whether it should be
 196 executed.
 197 An affirmative response,
 198 .Ql y
 199 in the POSIX locale,
 200 causes the command to be executed, any other response causes it to be
 201 skipped.
 202 No commands are executed if the process is not attached to a terminal.
 203 .It Fl R Ar replacements
 204 Specify the maximum number of arguments that
 205 .Fl I
 206 will do replacement in.
 207 .It Fl s Ar size
 208 Set the maximum number of bytes for the command line length provided to
 209 .Ar utility .
 210 The sum of the length of the utility name, the arguments passed to
 211 .Ar utility
 212 (including
 213 .Dv NULL
 214 terminators) and the current environment will be less than or equal to
 215 this number.
 216 The current default value for
 217 .Ar size
 218 is
 219 .Dv ARG_MAX
 220 - 4096.
 221 .It Fl t
 222 Echo the command to be executed to standard error immediately before it
 223 is executed.
 224 .It Fl x
 225 Force
 226 .Nm
 227 to terminate immediately if a command line containing
 228 .Ar number
 229 arguments will not fit in the specified (or default) command line length.
 230 .El
 231 .Pp
 232 If no
 233 .Ar utility
 234 is specified,
 235 .Xr echo 1
 236 is used.
 237 .Pp
 238 Undefined behavior may occur if
 239 .Ar utility
 240 reads from the standard input.
 241 .Pp
 242 The
 243 .Nm
 244 utility exits immediately (without processing any further input) if a
 245 command line cannot be assembled,
 246 .Ar utility
 247 cannot be invoked, an invocation of the utility is terminated by a signal
 248 or an invocation of the utility exits with a value of 255.
 249 .Sh DIAGNOSTICS
 250 The
 251 .Nm
 252 utility exits with a value of 0 if no error occurs.
 253 If
 254 .Ar utility
 255 cannot be found,
 256 .Nm
 257 exits with a value of 127, otherwise if
 258 .Ar utility
 259 cannot be executed,
 260 .Nm
 261 exits with a value of 126.
 262 If any other error occurs,
 263 .Nm
 264 exits with a value of 1.
 265 .Sh SEE ALSO
 266 .Xr echo 1 ,
 267 .Xr find 1 ,
 268 .Xr execvp 3
 269 .Sh STANDARDS
 270 The
 271 .Nm
 272 utility is expected to be
 273 .St -p1003.2
 274 compliant.
 275 The
 276 .Fl J
 277 and
 278 .Fl R
 279 options are non-standard
 280 .Fx
 281 extensions which may not be available on other operating systems.
 282 .Sh HISTORY
 283 The
 284 .Nm
 285 command appeared in PWB UNIX.
 286 .Sh BUGS
 287 If
 288 .Ar utility
 289 attempts to invoke another command such that the number of arguments or the
 290 size of the environment is increased, it risks
 291 .Xr execvp 3
 292 failing with
 293 .Er E2BIG .