1GETOPT(1) User Commands GETOPT(1)
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6 getopt - parse command options (enhanced)
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9 getopt optstring parameters getopt [options] [--] optstring parameters
10 getopt [options] -o|--options optstring [options] [--] parameters
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13 getopt is used to break up (parse) options in command lines for easy
14 parsing by shell procedures, and to check for valid options. It uses
15 the GNU getopt(3) routines to do this.
16 The parameters getopt is called with can be divided into two parts:
18 options which modify the way getopt will do the parsing (the options
19 and the optstring in the SYNOPSIS), and the parameters which are to be
20 parsed (parameters in the SYNOPSIS). The second part will start at the
21 first non-option parameter that is not an option argument, or after the
22 first occurrence of '--'. If no '-o' or '--options' option is found in
23 the first part, the first parameter of the second part is used as the
24 short options string.
25 If the environment variable GETOPT_COMPATIBLE is set, or if the first
27 parameter is not an option (does not start with a '-', the first format
28 in the SYNOPSIS), getopt will generate output that is compatible with
29 that of other versions of getopt(1). It will still do parameter
30 shuffling and recognize optional arguments (see section COMPATIBILITY
31 for more information).
32 Traditional implementations of getopt(1) are unable to cope with
34 whitespace and other (shell-specific) special characters in arguments
35 and non-option parameters. To solve this problem, this implementation
36 can generate quoted output which must once again be interpreted by the
37 shell (usually by using the eval command). This has the effect of
38 preserving those characters, but you must call getopt in a way that is
39 no longer compatible with other versions (the second or third format in
40 the SYNOPSIS). To determine whether this enhanced version of getopt(1)
41 is installed, a special test option (-T) can be used.
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44 -a, --alternative
45 Allow long options to start with a single '-'.
46 -h, --help
48 Display help text and exit. No other output is generated.
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 section SCANNING
72 MODES 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 -V, --version
99 Display version information and exit. No other output is generated.
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102 This section specifies the format of the second part of the parameters
103 of getopt (the parameters in the SYNOPSIS). The next section (OUTPUT)
104 describes the output that is generated. These parameters were typically
105 the parameters a shell function was called with. Care must be taken
106 that each parameter the shell function was called with corresponds to
107 exactly one parameter in the parameter list of getopt (see the
108 EXAMPLES). All parsing is done by the GNU getopt(3) routines.
109 The parameters are parsed from left to right. Each parameter is
111 classified as a short option, a long option, an argument to an option,
112 or a non-option parameter.
113 A simple short option is a '-' followed by a short option character. If
115 the option has a required argument, it may be written directly after
116 the option character or as the next parameter (i.e., separated by
117 whitespace on the command line). If the option has an optional
118 argument, it must be written directly after the option character if
119 present.
120 It is possible to specify several short options after one '-', as long
122 as all (except possibly the last) do not have required or optional
123 arguments.
124 A long option normally begins with '--' followed by the long option
126 name. If the option has a required argument, it may be written directly
127 after the long option name, separated by '=', or as the next argument
128 (i.e., separated by whitespace on the command line). If the option has
129 an optional argument, it must be written directly after the long option
130 name, separated by '=', if present (if you add the '=' but nothing
131 behind it, it is interpreted as if no argument was present; this is a
132 slight bug, see the BUGS). Long options may be abbreviated, as long as
133 the abbreviation is not ambiguous.
134 Each parameter not starting with a '-', and not a required argument of
136 a previous option, is a non-option parameter. Each parameter after a
137 '--' parameter is always interpreted as a non-option parameter. If the
138 environment variable POSIXLY_CORRECT is set, or if the short option
139 string started with a '+', all remaining parameters are interpreted as
140 non-option parameters as soon as the first non-option parameter is
141 found.
142
144 Output is generated for each element described in the previous section.
145 Output is done in the same order as the elements are specified in the
146 input, except for non-option parameters. Output can be done in
147 compatible (unquoted) mode, or in such way that whitespace and other
148 special characters within arguments and non-option parameters are
149 preserved (see QUOTING). When the output is processed in the shell
150 script, it will seem to be composed of distinct elements that can be
151 processed one by one (by using the shift command in most shell
152 languages). This is imperfect in unquoted mode, as elements can be
153 split at unexpected places if they contain whitespace or special
154 characters.
155 If there are problems parsing the parameters, for example because a
157 required argument is not found or an option is not recognized, an error
158 will be reported on stderr, there will be no output for the offending
159 element, and a non-zero error status is returned.
160 For a short option, a single '-' and the option character are generated
162 as one parameter. If the option has an argument, the next parameter
163 will be the argument. If the option takes an optional argument, but
164 none was found, the next parameter will be generated but be empty in
165 quoting mode, but no second parameter will be generated in unquoted
166 (compatible) mode. Note that many other getopt(1) implementations do
167 not support optional arguments.
168 If several short options were specified after a single '-', each will
170 be present in the output as a separate parameter.
171 For a long option, '--' and the full option name are generated as one
173 parameter. This is done regardless whether the option was abbreviated
174 or specified with a single '-' in the input. Arguments are handled as
175 with short options.
176 Normally, no non-option parameters output is generated until all
178 options and their arguments have been generated. Then '--' is generated
179 as a single parameter, and after it the non-option parameters in the
180 order they were found, each as a separate parameter. Only if the first
181 character of the short options string was a '-', non-option parameter
182 output is generated at the place they are found in the input (this is
183 not supported if the first format of the SYNOPSIS is used; in that case
184 all preceding occurrences of '-' and '+' are ignored).
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187 In compatibility mode, whitespace or 'special' characters in arguments
188 or non-option parameters are not handled correctly. As the output is
189 fed to the shell script, the script does not know how it is supposed to
190 break the output into separate parameters. To circumvent this problem,
191 this implementation offers quoting. The idea is that output is
192 generated with quotes around each parameter. When this output is once
193 again fed to the shell (usually by a shell eval command), it is split
194 correctly into separate parameters.
195 Quoting is not enabled if the environment variable GETOPT_COMPATIBLE is
197 set, if the first form of the SYNOPSIS is used, or if the option '-u'
198 is found.
199 Different shells use different quoting conventions. You can use the
201 '-s' option to select the shell you are using. The following shells are
202 currently supported: 'sh', 'bash', 'csh' and 'tcsh'. Actually, only two
203 'flavors' are distinguished: sh-like quoting conventions and csh-like
204 quoting conventions. Chances are that if you use another shell script
205 language, one of these flavors can still be used.
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208 The first character of the short options string may be a '-' or a '+'
209 to indicate a special scanning mode. If the first calling form in the
210 SYNOPSIS is used they are ignored; the environment variable
211 POSIXLY_CORRECT is still examined, though.
212 If the first character is '+', or if the environment variable
214 POSIXLY_CORRECT is set, parsing stops as soon as the first non-option
215 parameter (i.e., a parameter that does not start with a '-') is found
216 that is not an option argument. The remaining parameters are all
217 interpreted as non-option parameters.
218 If the first character is a '-', non-option parameters are outputted at
220 the place where they are found; in normal operation, they are all
221 collected at the end of output after a '--' parameter has been
222 generated. Note that this '--' parameter is still generated, but it
223 will always be the last parameter in this mode.
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226 This version of getopt(1) is written to be as compatible as possible to
227 other versions. Usually you can just replace them with this version
228 without any modifications, and with some advantages.
229 If the first character of the first parameter of getopt is not a '-',
231 getopt goes into compatibility mode. It will interpret its first
232 parameter as the string of short options, and all other arguments will
233 be parsed. It will still do parameter shuffling (i.e., all non-option
234 parameters are output at the end), unless the environment variable
235 POSIXLY_CORRECT is set, in which case, getopt will prepend a '+' before
236 short options automatically.
237 The environment variable GETOPT_COMPATIBLE forces getopt into
239 compatibility mode. Setting both this environment variable and
240 POSIXLY_CORRECT offers 100% compatibility for 'difficult' programs.
241 Usually, though, neither is needed.
242 In compatibility mode, leading '-' and '+' characters in the short
244 options string are ignored.
245
247 getopt returns error code 0 for successful parsing, 1 if getopt(3)
248 returns errors, 2 if it does not understand its own parameters, 3 if an
249 internal error occurs like out-of-memory, and 4 if it is called with
250 -T.
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253 Example scripts for (ba)sh and (t)csh are provided with the getopt(1)
254 distribution, and are installed in /usr/share/doc/util-linux directory.
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257 POSIXLY_CORRECT
258 This environment variable is examined by the getopt(3) routines. If
259 it is set, parsing stops as soon as a parameter is found that is
260 not an option or an option argument. All remaining parameters are
261 also interpreted as non-option parameters, regardless whether they
262 start with a '-'.
263 GETOPT_COMPATIBLE
265 Forces getopt to use the first calling format as specified in the
266 SYNOPSIS.
267
269 getopt(3) can parse long options with optional arguments that are given
270 an empty optional argument (but cannot do this for short options). This
271 getopt(1) treats optional arguments that are empty as if they were not
272 present.
273 The syntax if you do not want any short option variables at all is not
275 very intuitive (you have to set them explicitly to the empty string).
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278 Frodo Looijaard <frodo@frodo.looijaard.name>
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281 bash(1), tcsh(1), getopt(3)
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284 For bug reports, use the issue tracker at
285 https://github.com/karelzak/util-linux/issues.
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288 The getopt command is part of the util-linux package which can be
289 downloaded from Linux Kernel Archive
290 <https://www.kernel.org/pub/linux/utils/util-linux/>.
291util-linux 2.37.2 2021-06-02 GETOPT(1)