1xargs(1) User Commands xargs(1)
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6 xargs - construct argument lists and invoke utility
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9 xargs [-t] [-p] [-e[eofstr]] [-E eofstr]
10 [-I replstr] [-i[replstr]] [-L number] [-l[number]]
11 [-n number [-x]] [-s size] [utility [argument...]]
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15 The xargs utility constructs a command line consisting of the utility
16 and argument operands specified followed by as many arguments read in
17 sequence from standard input as fit in length and number constraints
18 specified by the options. The xargs utility then invokes the con‐
19 structed command line and waits for its completion. This sequence is
20 repeated until an end-of-file condition is detected on standard input
21 or an invocation of a constructed command line returns an exit status
22 of 255.
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25 Arguments in the standard input must be separated by unquoted blank
26 characters, or unescaped blank characters or newline characters. A
27 string of zero or more non-double-quote (") and non-newline characters
28 can be quoted by enclosing them in double-quotes. A string of zero or
29 more non-apostrophe (') and non-newline characters can be quoted by
30 enclosing them in apostrophes. Any unquoted character can be escaped by
31 preceding it with a backslash (\). The utility are executed one or more
32 times until the end-of-file is reached. The results are unspecified if
33 the utility named by utility attempts to read from its standard input.
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36 The generated command line length is the sum of the size in bytes of
37 the utility name and each argument treated as strings, including a null
38 byte terminator for each of these strings. The xargs utility limits the
39 command line length such that when the command line is invoked, the
40 combined argument and environment lists can not exceed {ARG_MAX}−2048
41 bytes. Within this constraint, if neither the -n nor the -s option is
42 specified, the default command line length is at least {LINE_MAX}.
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45 The following options are supported:
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47 -e[eofstr] Uses eofstr as the logical end-of-file string. Under‐
48 score (_) is assumed for the logical EOF string if nei‐
49 ther -e nor -E is used. When the eofstr option-argument
50 is omitted, the logical EOF string capability is dis‐
51 abled and underscores are taken literally. The xargs
52 utility reads standard input until either end-of-file or
53 the logical EOF string is encountered.
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56 -E eofstr Specifies a logical end-of-file string to replace the
57 default underscore. xargs reads standard input until
58 either end-of-file or the logical EOF string is encoun‐
59 tered. When eofstr is a null string, the logical end-of-
60 file string capability is disabled and underscore char‐
61 acters are taken literally.
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64 -I replstr Insert mode. utility is executed for each line from
65 standard input, taking the entire line as a single argu‐
66 ment, inserting it in argument s for each occurrence of
67 replstr. A maximum of five arguments in arguments can
68 each contain one or more instances of replstr. Any blank
69 characters at the beginning of each line are ignored.
70 Constructed arguments cannot grow larger than 255 bytes.
71 Option -x is forced on. The -I and -i options are mutu‐
72 ally exclusive; the last one specified takes effect.
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75 -i[replstr] This option is equivalent to -I replstr. The string {}
76 is assumed for replstr if the option-argument is omit‐
77 ted.
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80 -L number The utility is executed for each non-empty number lines
81 of arguments from standard input. The last invocation of
82 utility is with fewer lines of arguments if fewer than
83 number remain. A line is considered to end with the
84 first newline character unless the last character of the
85 line is a blank character; a trailing blank character
86 signals continuation to the next non-empty line, inclu‐
87 sive. The -L, -l, and -n options are mutually exclusive;
88 the last one specified takes effect.
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91 -l[number] (The letter ell.) This option is equivalent to -L num‐
92 ber. If number is omitted, 1 is assumed. Option -x is
93 forced on.
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96 -n number Invokes utility using as many standard input arguments
97 as possible, up to number (a positive decimal integer)
98 arguments maximum. Fewer arguments are used if:
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100 o The command line length accumulated exceeds
101 the size specified by the -s option (or
102 {LINE_MAX} if there is no -s option), or
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104 o The last iteration has fewer than number, but
105 not zero, operands remaining.
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108 -p Prompt mode. The user is asked whether to execute util‐
109 ity at each invocation. Trace mode (-t) is turned on to
110 write the command instance to be executed, followed by a
111 prompt to standard error. An affirmative response (spe‐
112 cific to the user's locale) read from /dev/tty executes
113 the command; otherwise, that particular invocation of
114 utility is skipped.
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117 -s size Invokes utility using as many standard input arguments
118 as possible yielding a command line length less than
119 size (a positive decimal integer) bytes. Fewer arguments
120 are used if:
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122 o The total number of arguments exceeds that
123 specified by the -n option, or
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125 o The total number of lines exceeds that speci‐
126 fied by the -L option, or
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128 o End of file is encountered on standard input
129 before size bytes are accumulated.
130 Values of size up to at least {LINE_MAX} bytes are sup‐
131 ported, provided that the constraints specified in
132 DESCRIPTION are met. It is not considered an error if a
133 value larger than that supported by the implementation
134 or exceeding the constraints specified in DESCRIPTION is
135 specified. xargs uses the largest value it supports
136 within the constraints.
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139 -t Enables trace mode. Each generated command line is written to
140 standard error just prior to invocation.
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143 -x Terminates if a command line containing number arguments (see the
144 -n option above) or number lines (see the -L option above) does
145 not fit in the implied or specified size (see the -s option
146 above).
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150 The following operands are supported:
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152 utility The name of the utility to be invoked, found by search path
153 using the PATH environment variable. (ee environ(5).) If
154 utility is omitted, the default is the echo(1) utility. If
155 the utility operand names any of the special built-in util‐
156 ities in shell_builtins(1), the results are undefined.
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159 argument An initial option or operand for the invocation of utility.
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163 The 255 exit status allows a utility being used by xargs to tell xargs
164 to terminate if it knows no further invocations using the current data
165 stream succeeds. Thus, utility should explicitly exit with an appropri‐
166 ate value to avoid accidentally returning with 255.
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169 Notice that input is parsed as lines. Blank characters separate argu‐
170 ments. If xargs is used to bundle output of commands like find dir
171 -print or ls into commands to be executed, unexpected results are
172 likely if any filenames contain any blank characters or newline charac‐
173 ters. This can be fixed by using find to call a script that converts
174 each file found into a quoted string that is then piped to xargs.
175 Notice that the quoting rules used by xargs are not the same as in the
176 shell. They were not made consistent here because existing applications
177 depend on the current rules and the shell syntax is not fully compati‐
178 ble with it. An easy rule that can be used to transform any string into
179 a quoted form that xargs interprets correctly is to precede each char‐
180 acter in the string with a backslash (\).
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183 On implementations with a large value for {ARG_MAX}, xargs can produce
184 command lines longer than {LINE_MAX}. For invocation of utilities, this
185 is not a problem. If xargs is being used to create a text file, users
186 should explicitly set the maximum command line length with the -s
187 option.
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190 The xargs utility returns exit status 127 if an error occurs so that
191 applications can distinguish "failure to find a utility" from "invoked
192 utility exited with an error indication." The value 127 was chosen
193 because it is not commonly used for other meanings; most utilities use
194 small values for "normal error conditions" and the values above 128 can
195 be confused with termination due to receipt of a signal. The value 126
196 was chosen in a similar manner to indicate that the utility could be
197 found, but not invoked.
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200 Example 1 Using the xargs command
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203 The following example moves all files from directory $1 to directory
204 $2, and echo each move command just before doing it:
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207 example% ls $1 | xargs -I {} -t mv $1/{} $2/{}
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212 The following command combines the output of the parenthesised commands
213 onto one line, which is then written to the end of file log:
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216 example% (logname; date; printf "%s\n" "$0 $*") | xargs >>log
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221 The following command invokes diff with successive pairs of arguments
222 originally typed as command line arguments (assuming there are no
223 embedded blank characters in the elements of the original argument
224 list):
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227 example% printf "%s\n" "$*" | xargs -n 2 -x diff
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232 The user is asked which files in the current directory are to be
233 archived. The files are archived into arch ; a, one at a time, or b,
234 many at a time:
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237 example% ls | xargs -p -L 1 ar -r arch
238 ls | xargs -p -L 1 | xargs ar -r arch
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243 The following executes with successive pairs of arguments originally
244 typed as command line arguments:
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247 example% echo $* | xargs -n 2 diff
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252 See environ(5) for descriptions of the following environment variables
253 that affect the execution of xargs: LANG, LC_ALL, LC_COLLATE, LC_CTYPE,
254 LC_MESSAGES, and NLSPATH.
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256 PATH Determine the location of utility.
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260 Affirmative responses are processed using the extended regular expres‐
261 sion defined for the yesexpr keyword in the LC_MESSAGES category of the
262 user's locale. The locale specified in the LC_COLLATE category defines
263 the behavior of ranges, equivalence classes, and multi-character col‐
264 lating elements used in the expression defined for yesexpr. The locale
265 specified in LC_CTYPE determines the locale for interpretation of
266 sequences of bytes of text data a characters, the behavior of character
267 classes used in the expression defined for the yesexpr. See locale(5).
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270 The following exit values are returned:
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272 0 All invocations of utility returned exit status 0.
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275 1−125 A command line meeting the specified requirements could not
276 be assembled, one or more of the invocations of utility
277 returned a non-zero exit status, or some other error
278 occurred.
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281 126 The utility specified by utility was found but could not be
282 invoked.
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285 127 The utility specified by utility could not be found.
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289 If a command line meeting the specified requirements cannot be assem‐
290 bled, the utility cannot be invoked, an invocation of the utility is
291 terminated by a signal, or an invocation of the utility exits with exit
292 status 255, the xargs utility writes a diagnostic message and exit
293 without processing any remaining input.
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296 See attributes(5) for descriptions of the following attributes:
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301 ┌─────────────────────────────┬─────────────────────────────┐
302 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
303 ├─────────────────────────────┼─────────────────────────────┤
304 │Availability │SUNWcsu │
305 ├─────────────────────────────┼─────────────────────────────┤
306 │CSI │Enabled │
307 ├─────────────────────────────┼─────────────────────────────┤
308 │Interface Stability │Standard │
309 └─────────────────────────────┴─────────────────────────────┘
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312 echo(1), shell_builtins(1), attributes(5), environ(5), standards(5)
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316SunOS 5.11 17 Jul 2007 xargs(1)