1GETOPT(1) User Commands GETOPT(1)
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6 getopt - parse command options (enhanced)
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9 getopt optstring parameters
10 getopt [options] [--] optstring parameters
12 getopt [options] -o|--options optstring [options] [--] parameters
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16 getopt is used to break up (parse) options in command lines for easy
17 parsing by shell procedures, and to check for valid options. It uses
18 the GNU getopt(3) routines to do this.
19 The parameters getopt is called with can be divided into two parts:
21 options which modify the way getopt will do the parsing (the options
22 and the optstring in the SYNOPSIS), and the parameters which are to be
23 parsed (parameters in the SYNOPSIS). The second part will start at the
24 first non-option parameter that is not an option argument, or after the
25 first occurrence of '--'. If no '-o' or '--options' option is found in
26 the first part, the first parameter of the second part is used as the
27 short options string.
28 If the environment variable GETOPT_COMPATIBLE is set, or if the first
30 parameter is not an option (does not start with a '-', the first format
31 in the SYNOPSIS), getopt will generate output that is compatible with
32 that of other versions of getopt(1). It will still do parameter
33 shuffling and recognize optional arguments (see the COMPATIBILITY
34 section for more information).
35 Traditional implementations of getopt(1) are unable to cope with
37 whitespace and other (shell-specific) special characters in arguments
38 and non-option parameters. To solve this problem, this implementation
39 can generate quoted output which must once again be interpreted by the
40 shell (usually by using the eval command). This has the effect of
41 preserving those characters, but you must call getopt in a way that is
42 no longer compatible with other versions (the second or third format in
43 the SYNOPSIS). To determine whether this enhanced version of getopt(1)
44 is installed, a special test option (-T) can be used.
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47 -a, --alternative
48 Allow long options to start with a single '-'.
49 -l, --longoptions longopts
51 The long (multi-character) options to be recognized. More than one
52 option name may be specified at once, by separating the names with
53 commas. This option may be given more than once, the longopts are
54 cumulative. Each long option name in longopts may be followed by
55 one colon to indicate it has a required argument, and by two colons
56 to indicate it has an optional argument.
57 -n, --name progname
59 The name that will be used by the getopt(3) routines when it
60 reports errors. Note that errors of getopt(1) are still reported as
61 coming from getopt.
62 -o, --options shortopts
64 The short (one-character) options to be recognized. If this option
65 is not found, the first parameter of getopt that does not start
66 with a '-' (and is not an option argument) is used as the short
67 options string. Each short option character in shortopts may be
68 followed by one colon to indicate it has a required argument, and
69 by two colons to indicate it has an optional argument. The first
70 character of shortopts may be '+' or '-' to influence the way
71 options are parsed and output is generated (see the SCANNING MODES
72 section for details).
73 -q, --quiet
75 Disable error reporting by getopt(3).
76 -Q, --quiet-output
78 Do not generate normal output. Errors are still reported by
79 getopt(3), unless you also use -q.
80 -s, --shell shell
82 Set quoting conventions to those of shell. If the -s option is not
83 given, the BASH conventions are used. Valid arguments are currently
84 'sh', 'bash', 'csh', and 'tcsh'.
85 -T, --test
87 Test if your getopt(1) is this enhanced version or an old version.
88 This generates no output, and sets the error status to 4. Other
89 implementations of getopt(1), and this version if the environment
90 variable GETOPT_COMPATIBLE is set, will return '--' and error
91 status 0.
92 -u, --unquoted
94 Do not quote the output. Note that whitespace and special
95 (shell-dependent) characters can cause havoc in this mode (like
96 they do with other getopt(1) implementations).
97 -h, --help
99 Display help text and exit.
100 -V, --version
102 Print version and exit.
103
105 This section specifies the format of the second part of the parameters
106 of getopt (the parameters in the SYNOPSIS). The next section (OUTPUT)
107 describes the output that is generated. These parameters were typically
108 the parameters a shell function was called with. Care must be taken
109 that each parameter the shell function was called with corresponds to
110 exactly one parameter in the parameter list of getopt (see the
111 EXAMPLES). All parsing is done by the GNU getopt(3) routines.
112 The parameters are parsed from left to right. Each parameter is
114 classified as a short option, a long option, an argument to an option,
115 or a non-option parameter.
116 A simple short option is a '-' followed by a short option character. If
118 the option has a required argument, it may be written directly after
119 the option character or as the next parameter (i.e., separated by
120 whitespace on the command line). If the option has an optional
121 argument, it must be written directly after the option character if
122 present.
123 It is possible to specify several short options after one '-', as long
125 as all (except possibly the last) do not have required or optional
126 arguments.
127 A long option normally begins with '--' followed by the long option
129 name. If the option has a required argument, it may be written directly
130 after the long option name, separated by '=', or as the next argument
131 (i.e., separated by whitespace on the command line). If the option has
132 an optional argument, it must be written directly after the long option
133 name, separated by '=', if present (if you add the '=' but nothing
134 behind it, it is interpreted as if no argument was present; this is a
135 slight bug, see the BUGS). Long options may be abbreviated, as long as
136 the abbreviation is not ambiguous.
137 Each parameter not starting with a '-', and not a required argument of
139 a previous option, is a non-option parameter. Each parameter after a
140 '--' parameter is always interpreted as a non-option parameter. If the
141 environment variable POSIXLY_CORRECT is set, or if the short option
142 string started with a '+', all remaining parameters are interpreted as
143 non-option parameters as soon as the first non-option parameter is
144 found.
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147 Output is generated for each element described in the previous section.
148 Output is done in the same order as the elements are specified in the
149 input, except for non-option parameters. Output can be done in
150 compatible (unquoted) mode, or in such way that whitespace and other
151 special characters within arguments and non-option parameters are
152 preserved (see QUOTING). When the output is processed in the shell
153 script, it will seem to be composed of distinct elements that can be
154 processed one by one (by using the shift command in most shell
155 languages). This is imperfect in unquoted mode, as elements can be
156 split at unexpected places if they contain whitespace or special
157 characters.
158 If there are problems parsing the parameters, for example because a
160 required argument is not found or an option is not recognized, an error
161 will be reported on stderr, there will be no output for the offending
162 element, and a non-zero error status is returned.
163 For a short option, a single '-' and the option character are generated
165 as one parameter. If the option has an argument, the next parameter
166 will be the argument. If the option takes an optional argument, but
167 none was found, the next parameter will be generated but be empty in
168 quoting mode, but no second parameter will be generated in unquoted
169 (compatible) mode. Note that many other getopt(1) implementations do
170 not support optional arguments.
171 If several short options were specified after a single '-', each will
173 be present in the output as a separate parameter.
174 For a long option, '--' and the full option name are generated as one
176 parameter. This is done regardless whether the option was abbreviated
177 or specified with a single '-' in the input. Arguments are handled as
178 with short options.
179 Normally, no non-option parameters output is generated until all
181 options and their arguments have been generated. Then '--' is generated
182 as a single parameter, and after it the non-option parameters in the
183 order they were found, each as a separate parameter. Only if the first
184 character of the short options string was a '-', non-option parameter
185 output is generated at the place they are found in the input (this is
186 not supported if the first format of the SYNOPSIS is used; in that case
187 all preceding occurrences of '-' and '+' are ignored).
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190 In compatibility mode, whitespace or 'special' characters in arguments
191 or non-option parameters are not handled correctly. As the output is
192 fed to the shell script, the script does not know how it is supposed to
193 break the output into separate parameters. To circumvent this problem,
194 this implementation offers quoting. The idea is that output is
195 generated with quotes around each parameter. When this output is once
196 again fed to the shell (usually by a shell eval command), it is split
197 correctly into separate parameters.
198 Quoting is not enabled if the environment variable GETOPT_COMPATIBLE is
200 set, if the first form of the SYNOPSIS is used, or if the option '-u'
201 is found.
202 Different shells use different quoting conventions. You can use the
204 '-s' option to select the shell you are using. The following shells are
205 currently supported: 'sh', 'bash', 'csh' and 'tcsh'. Actually, only two
206 'flavors' are distinguished: sh-like quoting conventions and csh-like
207 quoting conventions. Chances are that if you use another shell script
208 language, one of these flavors can still be used.
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211 The first character of the short options string may be a '-' or a '+'
212 to indicate a special scanning mode. If the first calling form in the
213 SYNOPSIS is used they are ignored; the environment variable
214 POSIXLY_CORRECT is still examined, though.
215 If the first character is '+', or if the environment variable
217 POSIXLY_CORRECT is set, parsing stops as soon as the first non-option
218 parameter (i.e., a parameter that does not start with a '-') is found
219 that is not an option argument. The remaining parameters are all
220 interpreted as non-option parameters.
221 If the first character is a '-', non-option parameters are outputted at
223 the place where they are found; in normal operation, they are all
224 collected at the end of output after a '--' parameter has been
225 generated. Note that this '--' parameter is still generated, but it
226 will always be the last parameter in this mode.
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229 This version of getopt(1) is written to be as compatible as possible to
230 other versions. Usually you can just replace them with this version
231 without any modifications, and with some advantages.
232 If the first character of the first parameter of getopt is not a '-',
234 getopt goes into compatibility mode. It will interpret its first
235 parameter as the string of short options, and all other arguments will
236 be parsed. It will still do parameter shuffling (i.e., all non-option
237 parameters are output at the end), unless the environment variable
238 POSIXLY_CORRECT is set, in which case, getopt will prepend a '+' before
239 short options automatically.
240 The environment variable GETOPT_COMPATIBLE forces getopt into
242 compatibility mode. Setting both this environment variable and
243 POSIXLY_CORRECT offers 100% compatibility for 'difficult' programs.
244 Usually, though, neither is needed.
245 In compatibility mode, leading '-' and '+' characters in the short
247 options string are ignored.
248
250 getopt returns error code 0 for successful parsing, 1 if getopt(3)
251 returns errors, 2 if it does not understand its own parameters, 3 if an
252 internal error occurs like out-of-memory, and 4 if it is called with
253 -T.
254
256 Example scripts for (ba)sh and (t)csh are provided with the getopt(1)
257 distribution, and are installed in /usr/share/doc/util-linux directory.
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260 POSIXLY_CORRECT
261 This environment variable is examined by the getopt(3) routines. If
262 it is set, parsing stops as soon as a parameter is found that is
263 not an option or an option argument. All remaining parameters are
264 also interpreted as non-option parameters, regardless whether they
265 start with a '-'.
266 GETOPT_COMPATIBLE
268 Forces getopt to use the first calling format as specified in the
269 SYNOPSIS.
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272 getopt(3) can parse long options with optional arguments that are given
273 an empty optional argument (but cannot do this for short options). This
274 getopt(1) treats optional arguments that are empty as if they were not
275 present.
276 The syntax if you do not want any short option variables at all is not
278 very intuitive (you have to set them explicitly to the empty string).
279
281 Frodo Looijaard <frodo@frodo.looijaard.name>
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284 bash(1), tcsh(1), getopt(3)
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287 For bug reports, use the issue tracker at
288 https://github.com/util-linux/util-linux/issues.
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291 The getopt command is part of the util-linux package which can be
292 downloaded from Linux Kernel Archive
293 <https://www.kernel.org/pub/linux/utils/util-linux/>.
294util-linux 2.39.2 2023-06-14 GETOPT(1)