1Getopt::Long(3) User Contributed Perl Documentation Getopt::Long(3)
2
6 Getopt::Long - Extended processing of command line options
7
9 use Getopt::Long;
10 my $data = "file.dat";
11 my $length = 24;
12 my $verbose;
13 GetOptions ("length=i" => \$length, # numeric
14 "file=s" => \$data, # string
15 "verbose" => \$verbose) # flag
16 or die("Error in command line arguments\n");
17
19 The Getopt::Long module implements an extended getopt function called
20 GetOptions(). It parses the command line from @ARGV, recognizing and
21 removing specified options and their possible values.
22 This function adheres to the POSIX syntax for command line options,
24 with GNU extensions. In general, this means that options have long
25 names instead of single letters, and are introduced with a double dash
26 "--". Support for bundling of command line options, as was the case
27 with the more traditional single-letter approach, is provided but not
28 enabled by default.
29
31 Command line operated programs traditionally take their arguments from
32 the command line, for example filenames or other information that the
33 program needs to know. Besides arguments, these programs often take
34 command line options as well. Options are not necessary for the program
35 to work, hence the name 'option', but are used to modify its default
36 behaviour. For example, a program could do its job quietly, but with a
37 suitable option it could provide verbose information about what it did.
38 Command line options come in several flavours. Historically, they are
40 preceded by a single dash "-", and consist of a single letter.
41 -l -a -c
43 Usually, these single-character options can be bundled:
45 -lac
47 Options can have values, the value is placed after the option
49 character. Sometimes with whitespace in between, sometimes not:
50 -s 24 -s24
52 Due to the very cryptic nature of these options, another style was
54 developed that used long names. So instead of a cryptic "-l" one could
55 use the more descriptive "--long". To distinguish between a bundle of
56 single-character options and a long one, two dashes are used to precede
57 the option name. Early implementations of long options used a plus "+"
58 instead. Also, option values could be specified either like
59 --size=24
61 or
63 --size 24
65 The "+" form is now obsolete and strongly deprecated.
67
69 Getopt::Long is the Perl5 successor of "newgetopt.pl". This was the
70 first Perl module that provided support for handling the new style of
71 command line options, in particular long option names, hence the Perl5
72 name Getopt::Long. This module also supports single-character options
73 and bundling.
74 To use Getopt::Long from a Perl program, you must include the following
76 line in your Perl program:
77 use Getopt::Long;
79 This will load the core of the Getopt::Long module and prepare your
81 program for using it. Most of the actual Getopt::Long code is not
82 loaded until you really call one of its functions.
83 In the default configuration, options names may be abbreviated to
85 uniqueness, case does not matter, and a single dash is sufficient, even
86 for long option names. Also, options may be placed between non-option
87 arguments. See "Configuring Getopt::Long" for more details on how to
88 configure Getopt::Long.
89 Simple options
91 The most simple options are the ones that take no values. Their mere
92 presence on the command line enables the option. Popular examples are:
93 --all --verbose --quiet --debug
95 Handling simple options is straightforward:
97 my $verbose = ''; # option variable with default value (false)
99 my $all = ''; # option variable with default value (false)
100 GetOptions ('verbose' => \$verbose, 'all' => \$all);
101 The call to GetOptions() parses the command line arguments that are
103 present in @ARGV and sets the option variable to the value 1 if the
104 option did occur on the command line. Otherwise, the option variable is
105 not touched. Setting the option value to true is often called enabling
106 the option.
107 The option name as specified to the GetOptions() function is called the
109 option specification. Later we'll see that this specification can
110 contain more than just the option name. The reference to the variable
111 is called the option destination.
112 GetOptions() will return a true value if the command line could be
114 processed successfully. Otherwise, it will write error messages using
115 die() and warn(), and return a false result.
116 A little bit less simple options
118 Getopt::Long supports two useful variants of simple options: negatable
119 options and incremental options.
120 A negatable option is specified with an exclamation mark "!" after the
122 option name:
123 my $verbose = ''; # option variable with default value (false)
125 GetOptions ('verbose!' => \$verbose);
126 Now, using "--verbose" on the command line will enable $verbose, as
128 expected. But it is also allowed to use "--noverbose", which will
129 disable $verbose by setting its value to 0. Using a suitable default
130 value, the program can find out whether $verbose is false by default,
131 or disabled by using "--noverbose".
132 (If both "--verbose" and "--noverbose" are given, whichever is given
134 last takes precedence.)
135 An incremental option is specified with a plus "+" after the option
137 name:
138 my $verbose = ''; # option variable with default value (false)
140 GetOptions ('verbose+' => \$verbose);
141 Using "--verbose" on the command line will increment the value of
143 $verbose. This way the program can keep track of how many times the
144 option occurred on the command line. For example, each occurrence of
145 "--verbose" could increase the verbosity level of the program.
146 Mixing command line option with other arguments
148 Usually programs take command line options as well as other arguments,
149 for example, file names. It is good practice to always specify the
150 options first, and the other arguments last. Getopt::Long will,
151 however, allow the options and arguments to be mixed and 'filter out'
152 all the options before passing the rest of the arguments to the
153 program. To stop Getopt::Long from processing further arguments, insert
154 a double dash "--" on the command line:
155 --size 24 -- --all
157 In this example, "--all" will not be treated as an option, but passed
159 to the program unharmed, in @ARGV.
160 Options with values
162 For options that take values it must be specified whether the option
163 value is required or not, and what kind of value the option expects.
164 Three kinds of values are supported: integer numbers, floating point
166 numbers, and strings.
167 If the option value is required, Getopt::Long will take the command
169 line argument that follows the option and assign this to the option
170 variable. If, however, the option value is specified as optional, this
171 will only be done if that value does not look like a valid command line
172 option itself.
173 my $tag = ''; # option variable with default value
175 GetOptions ('tag=s' => \$tag);
176 In the option specification, the option name is followed by an equals
178 sign "=" and the letter "s". The equals sign indicates that this option
179 requires a value. The letter "s" indicates that this value is an
180 arbitrary string. Other possible value types are "i" for integer
181 values, and "f" for floating point values. Using a colon ":" instead of
182 the equals sign indicates that the option value is optional. In this
183 case, if no suitable value is supplied, string valued options get an
184 empty string '' assigned, while numeric options are set to 0.
185 (If the same option appears more than once on the command line, the
187 last given value is used. If you want to take all the values, see
188 below.)
189 Options with multiple values
191 Options sometimes take several values. For example, a program could use
192 multiple directories to search for library files:
193 --library lib/stdlib --library lib/extlib
195 To accomplish this behaviour, simply specify an array reference as the
197 destination for the option:
198 GetOptions ("library=s" => \@libfiles);
200 Alternatively, you can specify that the option can have multiple values
202 by adding a "@", and pass a reference to a scalar as the destination:
203 GetOptions ("library=s@" => \$libfiles);
205 Used with the example above, @libfiles c.q. @$libfiles would contain
207 two strings upon completion: "lib/stdlib" and "lib/extlib", in that
208 order. It is also possible to specify that only integer or floating
209 point numbers are acceptable values.
210 Often it is useful to allow comma-separated lists of values as well as
212 multiple occurrences of the options. This is easy using Perl's split()
213 and join() operators:
214 GetOptions ("library=s" => \@libfiles);
216 @libfiles = split(/,/,join(',',@libfiles));
217 Of course, it is important to choose the right separator string for
219 each purpose.
220 Warning: What follows is an experimental feature.
222 Options can take multiple values at once, for example
224 --coordinates 52.2 16.4 --rgbcolor 255 255 149
226 This can be accomplished by adding a repeat specifier to the option
228 specification. Repeat specifiers are very similar to the "{...}" repeat
229 specifiers that can be used with regular expression patterns. For
230 example, the above command line would be handled as follows:
231 GetOptions('coordinates=f{2}' => \@coor, 'rgbcolor=i{3}' => \@color);
233 The destination for the option must be an array or array reference.
235 It is also possible to specify the minimal and maximal number of
237 arguments an option takes. "foo=s{2,4}" indicates an option that takes
238 at least two and at most 4 arguments. "foo=s{1,}" indicates one or more
239 values; "foo:s{,}" indicates zero or more option values.
240 Options with hash values
242 If the option destination is a reference to a hash, the option will
243 take, as value, strings of the form key"="value. The value will be
244 stored with the specified key in the hash.
245 GetOptions ("define=s" => \%defines);
247 Alternatively you can use:
249 GetOptions ("define=s%" => \$defines);
251 When used with command line options:
253 --define os=linux --define vendor=redhat
255 the hash %defines (or %$defines) will contain two keys, "os" with value
257 "linux" and "vendor" with value "redhat". It is also possible to
258 specify that only integer or floating point numbers are acceptable
259 values. The keys are always taken to be strings.
260 User-defined subroutines to handle options
262 Ultimate control over what should be done when (actually: each time) an
263 option is encountered on the command line can be achieved by
264 designating a reference to a subroutine (or an anonymous subroutine) as
265 the option destination. When GetOptions() encounters the option, it
266 will call the subroutine with two or three arguments. The first
267 argument is the name of the option. (Actually, it is an object that
268 stringifies to the name of the option.) For a scalar or array
269 destination, the second argument is the value to be stored. For a hash
270 destination, the second argument is the key to the hash, and the third
271 argument the value to be stored. It is up to the subroutine to store
272 the value, or do whatever it thinks is appropriate.
273 A trivial application of this mechanism is to implement options that
275 are related to each other. For example:
276 my $verbose = ''; # option variable with default value (false)
278 GetOptions ('verbose' => \$verbose,
279 'quiet' => sub { $verbose = 0 });
280 Here "--verbose" and "--quiet" control the same variable $verbose, but
282 with opposite values.
283 If the subroutine needs to signal an error, it should call die() with
285 the desired error message as its argument. GetOptions() will catch the
286 die(), issue the error message, and record that an error result must be
287 returned upon completion.
288 If the text of the error message starts with an exclamation mark "!"
290 it is interpreted specially by GetOptions(). There is currently one
291 special command implemented: die("!FINISH") will cause GetOptions() to
292 stop processing options, as if it encountered a double dash "--".
293 Here is an example of how to access the option name and value from
295 within a subroutine:
296 GetOptions ('opt=i' => \&handler);
298 sub handler {
299 my ($opt_name, $opt_value) = @_;
300 print("Option name is $opt_name and value is $opt_value\n");
301 }
302 Options with multiple names
304 Often it is user friendly to supply alternate mnemonic names for
305 options. For example "--height" could be an alternate name for
306 "--length". Alternate names can be included in the option
307 specification, separated by vertical bar "|" characters. To implement
308 the above example:
309 GetOptions ('length|height=f' => \$length);
311 The first name is called the primary name, the other names are called
313 aliases. When using a hash to store options, the key will always be the
314 primary name.
315 Multiple alternate names are possible.
317 Case and abbreviations
319 Without additional configuration, GetOptions() will ignore the case of
320 option names, and allow the options to be abbreviated to uniqueness.
321 GetOptions ('length|height=f' => \$length, "head" => \$head);
323 This call will allow "--l" and "--L" for the length option, but
325 requires a least "--hea" and "--hei" for the head and height options.
326 Summary of Option Specifications
328 Each option specifier consists of two parts: the name specification and
329 the argument specification.
330 The name specification contains the name of the option, optionally
332 followed by a list of alternative names separated by vertical bar
333 characters.
334 length option name is "length"
336 length|size|l name is "length", aliases are "size" and "l"
337 The argument specification is optional. If omitted, the option is
339 considered boolean, a value of 1 will be assigned when the option is
340 used on the command line.
341 The argument specification can be
343 ! The option does not take an argument and may be negated by
345 prefixing it with "no" or "no-". E.g. "foo!" will allow "--foo" (a
346 value of 1 will be assigned) as well as "--nofoo" and "--no-foo" (a
347 value of 0 will be assigned). If the option has aliases, this
348 applies to the aliases as well.
349 Using negation on a single letter option when bundling is in effect
351 is pointless and will result in a warning.
352 + The option does not take an argument and will be incremented by 1
354 every time it appears on the command line. E.g. "more+", when used
355 with "--more --more --more", will increment the value three times,
356 resulting in a value of 3 (provided it was 0 or undefined at
357 first).
358 The "+" specifier is ignored if the option destination is not a
360 scalar.
361 = type [ desttype ] [ repeat ]
363 The option requires an argument of the given type. Supported types
364 are:
365 s String. An arbitrary sequence of characters. It is valid for
367 the argument to start with "-" or "--".
368 i Integer. An optional leading plus or minus sign, followed by a
370 sequence of digits.
371 o Extended integer, Perl style. This can be either an optional
373 leading plus or minus sign, followed by a sequence of digits,
374 or an octal string (a zero, optionally followed by '0', '1', ..
375 '7'), or a hexadecimal string ("0x" followed by '0' .. '9', 'a'
376 .. 'f', case insensitive), or a binary string ("0b" followed by
377 a series of '0' and '1').
378 f Real number. For example 3.14, -6.23E24 and so on.
380 The desttype can be "@" or "%" to specify that the option is list
382 or a hash valued. This is only needed when the destination for the
383 option value is not otherwise specified. It should be omitted when
384 not needed.
385 The repeat specifies the number of values this option takes per
387 occurrence on the command line. It has the format "{" [ min ] [ ","
388 [ max ] ] "}".
389 min denotes the minimal number of arguments. It defaults to 1 for
391 options with "=" and to 0 for options with ":", see below. Note
392 that min overrules the "=" / ":" semantics.
393 max denotes the maximum number of arguments. It must be at least
395 min. If max is omitted, but the comma is not, there is no upper
396 bound to the number of argument values taken.
397 : type [ desttype ]
399 Like "=", but designates the argument as optional. If omitted, an
400 empty string will be assigned to string values options, and the
401 value zero to numeric options.
402 Note that if a string argument starts with "-" or "--", it will be
404 considered an option on itself.
405 : number [ desttype ]
407 Like ":i", but if the value is omitted, the number will be
408 assigned.
409 If the number is octal, hexadecimal or binary, behaves like ":o".
411 : + [ desttype ]
413 Like ":i", but if the value is omitted, the current value for the
414 option will be incremented.
415
417 Object oriented interface
418 Getopt::Long can be used in an object oriented way as well:
419 use Getopt::Long;
421 $p = Getopt::Long::Parser->new;
422 $p->configure(...configuration options...);
423 if ($p->getoptions(...options descriptions...)) ...
424 if ($p->getoptionsfromarray( \@array, ...options descriptions...)) ...
425 Configuration options can be passed to the constructor:
427 $p = new Getopt::Long::Parser
429 config => [...configuration options...];
430 Callback object
432 In version 2.37 the first argument to the callback function was changed
433 from string to object. This was done to make room for extensions and
434 more detailed control. The object stringifies to the option name so
435 this change should not introduce compatibility problems.
436 The callback object has the following methods:
438 name
440 The name of the option, unabbreviated. For an option with multiple
441 names it return the first (canonical) name.
442 given
444 The name of the option as actually used, unabbreveated.
445 Thread Safety
447 Getopt::Long is thread safe when using ithreads as of Perl 5.8. It is
448 not thread safe when using the older (experimental and now obsolete)
449 threads implementation that was added to Perl 5.005.
450 Documentation and help texts
452 Getopt::Long encourages the use of Pod::Usage to produce help messages.
453 For example:
454 use Getopt::Long;
456 use Pod::Usage;
457 my $man = 0;
459 my $help = 0;
460 GetOptions('help|?' => \$help, man => \$man) or pod2usage(2);
462 pod2usage(1) if $help;
463 pod2usage(-exitval => 0, -verbose => 2) if $man;
464 __END__
466 =head1 NAME
468 sample - Using Getopt::Long and Pod::Usage
470 =head1 SYNOPSIS
472 sample [options] [file ...]
474 Options:
476 -help brief help message
477 -man full documentation
478 =head1 OPTIONS
480 =over 8
482 =item B<-help>
484 Print a brief help message and exits.
486 =item B<-man>
488 Prints the manual page and exits.
490 =back
492 =head1 DESCRIPTION
494 B<This program> will read the given input file(s) and do something
496 useful with the contents thereof.
497 =cut
499 See Pod::Usage for details.
501 Parsing options from an arbitrary array
503 By default, GetOptions parses the options that are present in the
504 global array @ARGV. A special entry "GetOptionsFromArray" can be used
505 to parse options from an arbitrary array.
506 use Getopt::Long qw(GetOptionsFromArray);
508 $ret = GetOptionsFromArray(\@myopts, ...);
509 When used like this, options and their possible values are removed from
511 @myopts, the global @ARGV is not touched at all.
512 The following two calls behave identically:
514 $ret = GetOptions( ... );
516 $ret = GetOptionsFromArray(\@ARGV, ... );
517 This also means that a first argument hash reference now becomes the
519 second argument:
520 $ret = GetOptions(\%opts, ... );
522 $ret = GetOptionsFromArray(\@ARGV, \%opts, ... );
523 Parsing options from an arbitrary string
525 A special entry "GetOptionsFromString" can be used to parse options
526 from an arbitrary string.
527 use Getopt::Long qw(GetOptionsFromString);
529 $ret = GetOptionsFromString($string, ...);
530 The contents of the string are split into arguments using a call to
532 "Text::ParseWords::shellwords". As with "GetOptionsFromArray", the
533 global @ARGV is not touched.
534 It is possible that, upon completion, not all arguments in the string
536 have been processed. "GetOptionsFromString" will, when called in list
537 context, return both the return status and an array reference to any
538 remaining arguments:
539 ($ret, $args) = GetOptionsFromString($string, ... );
541 If any arguments remain, and "GetOptionsFromString" was not called in
543 list context, a message will be given and "GetOptionsFromString" will
544 return failure.
545 As with GetOptionsFromArray, a first argument hash reference now
547 becomes the second argument. See the next section.
548 Storing options values in a hash
550 Sometimes, for example when there are a lot of options, having a
551 separate variable for each of them can be cumbersome. GetOptions()
552 supports, as an alternative mechanism, storing options values in a
553 hash.
554 To obtain this, a reference to a hash must be passed as the first
556 argument to GetOptions(). For each option that is specified on the
557 command line, the option value will be stored in the hash with the
558 option name as key. Options that are not actually used on the command
559 line will not be put in the hash, on other words, exists($h{option})
560 (or defined()) can be used to test if an option was used. The drawback
561 is that warnings will be issued if the program runs under "use strict"
562 and uses $h{option} without testing with exists() or defined() first.
563 my %h = ();
565 GetOptions (\%h, 'length=i'); # will store in $h{length}
566 For options that take list or hash values, it is necessary to indicate
568 this by appending an "@" or "%" sign after the type:
569 GetOptions (\%h, 'colours=s@'); # will push to @{$h{colours}}
571 To make things more complicated, the hash may contain references to the
573 actual destinations, for example:
574 my $len = 0;
576 my %h = ('length' => \$len);
577 GetOptions (\%h, 'length=i'); # will store in $len
578 This example is fully equivalent with:
580 my $len = 0;
582 GetOptions ('length=i' => \$len); # will store in $len
583 Any mixture is possible. For example, the most frequently used options
585 could be stored in variables while all other options get stored in the
586 hash:
587 my $verbose = 0; # frequently referred
589 my $debug = 0; # frequently referred
590 my %h = ('verbose' => \$verbose, 'debug' => \$debug);
591 GetOptions (\%h, 'verbose', 'debug', 'filter', 'size=i');
592 if ( $verbose ) { ... }
593 if ( exists $h{filter} ) { ... option 'filter' was specified ... }
594 Bundling
596 With bundling it is possible to set several single-character options at
597 once. For example if "a", "v" and "x" are all valid options,
598 -vax
600 will set all three.
602 Getopt::Long supports three styles of bundling. To enable bundling, a
604 call to Getopt::Long::Configure is required.
605 The simplest style of bundling can be enabled with:
607 Getopt::Long::Configure ("bundling");
609 Configured this way, single-character options can be bundled but long
611 options (and any of their auto-abbreviated shortened forms) must always
612 start with a double dash "--" to avoid ambiguity. For example, when
613 "vax", "a", "v" and "x" are all valid options,
614 -vax
616 will set "a", "v" and "x", but
618 --vax
620 will set "vax".
622 The second style of bundling lifts this restriction. It can be enabled
624 with:
625 Getopt::Long::Configure ("bundling_override");
627 Now, "-vax" will set the option "vax".
629 In all of the above cases, option values may be inserted in the bundle.
631 For example:
632 -h24w80
634 is equivalent to
636 -h 24 -w 80
638 A third style of bundling allows only values to be bundled with
640 options. It can be enabled with:
641 Getopt::Long::Configure ("bundling_values");
643 Now, "-h24" will set the option "h" to 24, but option bundles like
645 "-vxa" and "-h24w80" are flagged as errors.
646 Enabling "bundling_values" will disable the other two styles of
648 bundling.
649 When configured for bundling, single-character options are matched case
651 sensitive while long options are matched case insensitive. To have the
652 single-character options matched case insensitive as well, use:
653 Getopt::Long::Configure ("bundling", "ignorecase_always");
655 It goes without saying that bundling can be quite confusing.
657 The lonesome dash
659 Normally, a lone dash "-" on the command line will not be considered an
660 option. Option processing will terminate (unless "permute" is
661 configured) and the dash will be left in @ARGV.
662 It is possible to get special treatment for a lone dash. This can be
664 achieved by adding an option specification with an empty name, for
665 example:
666 GetOptions ('' => \$stdio);
668 A lone dash on the command line will now be a legal option, and using
670 it will set variable $stdio.
671 Argument callback
673 A special option 'name' "<>" can be used to designate a subroutine to
674 handle non-option arguments. When GetOptions() encounters an argument
675 that does not look like an option, it will immediately call this
676 subroutine and passes it one parameter: the argument name.
677 For example:
679 my $width = 80;
681 sub process { ... }
682 GetOptions ('width=i' => \$width, '<>' => \&process);
683 When applied to the following command line:
685 arg1 --width=72 arg2 --width=60 arg3
687 This will call process("arg1") while $width is 80, process("arg2")
689 while $width is 72, and process("arg3") while $width is 60.
690 This feature requires configuration option permute, see section
692 "Configuring Getopt::Long".
693
695 Getopt::Long can be configured by calling subroutine
696 Getopt::Long::Configure(). This subroutine takes a list of quoted
697 strings, each specifying a configuration option to be enabled, e.g.
698 "ignore_case". To disable, prefix with "no" or "no_", e.g.
699 "no_ignore_case". Case does not matter. Multiple calls to Configure()
700 are possible.
701 Alternatively, as of version 2.24, the configuration options may be
703 passed together with the "use" statement:
704 use Getopt::Long qw(:config no_ignore_case bundling);
706 The following options are available:
708 default This option causes all configuration options to be reset to
710 their default values.
711 posix_default
713 This option causes all configuration options to be reset to
714 their default values as if the environment variable
715 POSIXLY_CORRECT had been set.
716 auto_abbrev Allow option names to be abbreviated to uniqueness.
718 Default is enabled unless environment variable
719 POSIXLY_CORRECT has been set, in which case "auto_abbrev"
720 is disabled.
721 getopt_compat
723 Allow "+" to start options. Default is enabled unless
724 environment variable POSIXLY_CORRECT has been set, in which
725 case "getopt_compat" is disabled.
726 gnu_compat "gnu_compat" controls whether "--opt=" is allowed, and what
728 it should do. Without "gnu_compat", "--opt=" gives an
729 error. With "gnu_compat", "--opt=" will give option "opt"
730 and empty value. This is the way GNU getopt_long() does
731 it.
732 Note that "--opt value" is still accepted, even though GNU
734 getopt_long() doesn't.
735 gnu_getopt This is a short way of setting "gnu_compat" "bundling"
737 "permute" "no_getopt_compat". With "gnu_getopt", command
738 line handling should be reasonably compatible with GNU
739 getopt_long().
740 require_order
742 Whether command line arguments are allowed to be mixed with
743 options. Default is disabled unless environment variable
744 POSIXLY_CORRECT has been set, in which case "require_order"
745 is enabled.
746 See also "permute", which is the opposite of
748 "require_order".
749 permute Whether command line arguments are allowed to be mixed with
751 options. Default is enabled unless environment variable
752 POSIXLY_CORRECT has been set, in which case "permute" is
753 disabled. Note that "permute" is the opposite of
754 "require_order".
755 If "permute" is enabled, this means that
757 --foo arg1 --bar arg2 arg3
759 is equivalent to
761 --foo --bar arg1 arg2 arg3
763 If an argument callback routine is specified, @ARGV will
765 always be empty upon successful return of GetOptions()
766 since all options have been processed. The only exception
767 is when "--" is used:
768 --foo arg1 --bar arg2 -- arg3
770 This will call the callback routine for arg1 and arg2, and
772 then terminate GetOptions() leaving "arg3" in @ARGV.
773 If "require_order" is enabled, options processing
775 terminates when the first non-option is encountered.
776 --foo arg1 --bar arg2 arg3
778 is equivalent to
780 --foo -- arg1 --bar arg2 arg3
782 If "pass_through" is also enabled, options processing will
784 terminate at the first unrecognized option, or non-option,
785 whichever comes first.
786 bundling (default: disabled)
788 Enabling this option will allow single-character options to
789 be bundled. To distinguish bundles from long option names,
790 long options (and any of their auto-abbreviated shortened
791 forms) must be introduced with "--" and bundles with "-".
792 Note that, if you have options "a", "l" and "all", and
794 auto_abbrev enabled, possible arguments and option settings
795 are:
796 using argument sets option(s)
798 ------------------------------------------
799 -a, --a a
800 -l, --l l
801 -al, -la, -ala, -all,... a, l
802 --al, --all all
803 The surprising part is that "--a" sets option "a" (due to
805 auto completion), not "all".
806 Note: disabling "bundling" also disables
808 "bundling_override".
809 bundling_override (default: disabled)
811 If "bundling_override" is enabled, bundling is enabled as
812 with "bundling" but now long option names override option
813 bundles.
814 Note: disabling "bundling_override" also disables
816 "bundling".
817 Note: Using option bundling can easily lead to unexpected
819 results, especially when mixing long options and bundles.
820 Caveat emptor.
821 ignore_case (default: enabled)
823 If enabled, case is ignored when matching option names. If,
824 however, bundling is enabled as well, single character
825 options will be treated case-sensitive.
826 With "ignore_case", option specifications for options that
828 only differ in case, e.g., "foo" and "Foo", will be flagged
829 as duplicates.
830 Note: disabling "ignore_case" also disables
832 "ignore_case_always".
833 ignore_case_always (default: disabled)
835 When bundling is in effect, case is ignored on single-
836 character options also.
837 Note: disabling "ignore_case_always" also disables
839 "ignore_case".
840 auto_version (default:disabled)
842 Automatically provide support for the --version option if
843 the application did not specify a handler for this option
844 itself.
845 Getopt::Long will provide a standard version message that
847 includes the program name, its version (if $main::VERSION
848 is defined), and the versions of Getopt::Long and Perl. The
849 message will be written to standard output and processing
850 will terminate.
851 "auto_version" will be enabled if the calling program
853 explicitly specified a version number higher than 2.32 in
854 the "use" or "require" statement.
855 auto_help (default:disabled)
857 Automatically provide support for the --help and -? options
858 if the application did not specify a handler for this
859 option itself.
860 Getopt::Long will provide a help message using module
862 Pod::Usage. The message, derived from the SYNOPSIS POD
863 section, will be written to standard output and processing
864 will terminate.
865 "auto_help" will be enabled if the calling program
867 explicitly specified a version number higher than 2.32 in
868 the "use" or "require" statement.
869 pass_through (default: disabled)
871 With "pass_through" anything that is unknown, ambiguous or
872 supplied with an invalid option will not be flagged as an
873 error. Instead the unknown option(s) will be passed to the
874 catchall "<>" if present, otherwise through to @ARGV. This
875 makes it possible to write wrapper scripts that process
876 only part of the user supplied command line arguments, and
877 pass the remaining options to some other program.
878 If "require_order" is enabled, options processing will
880 terminate at the first unrecognized option, or non-option,
881 whichever comes first and all remaining arguments are
882 passed to @ARGV instead of the catchall "<>" if present.
883 However, if "permute" is enabled instead, results can
884 become confusing.
885 Note that the options terminator (default "--"), if
887 present, will also be passed through in @ARGV.
888 prefix The string that starts options. If a constant string is not
890 sufficient, see "prefix_pattern".
891 prefix_pattern
893 A Perl pattern that identifies the strings that introduce
894 options. Default is "--|-|\+" unless environment variable
895 POSIXLY_CORRECT has been set, in which case it is "--|-".
896 long_prefix_pattern
898 A Perl pattern that allows the disambiguation of long and
899 short prefixes. Default is "--".
900 Typically you only need to set this if you are using
902 nonstandard prefixes and want some or all of them to have
903 the same semantics as '--' does under normal circumstances.
904 For example, setting prefix_pattern to "--|-|\+|\/" and
906 long_prefix_pattern to "--|\/" would add Win32 style
907 argument handling.
908 debug (default: disabled)
910 Enable debugging output.
911
913 VersionMessage
914 This subroutine provides a standard version message. Its argument
915 can be:
916 • A string containing the text of a message to print before
918 printing the standard message.
919 • A numeric value corresponding to the desired exit status.
921 • A reference to a hash.
923 If more than one argument is given then the entire argument list is
925 assumed to be a hash. If a hash is supplied (either as a reference
926 or as a list) it should contain one or more elements with the
927 following keys:
928 "-message"
930 "-msg"
931 The text of a message to print immediately prior to printing
932 the program's usage message.
933 "-exitval"
935 The desired exit status to pass to the exit() function. This
936 should be an integer, or else the string "NOEXIT" to indicate
937 that control should simply be returned without terminating the
938 invoking process.
939 "-output"
941 A reference to a filehandle, or the pathname of a file to which
942 the usage message should be written. The default is "\*STDERR"
943 unless the exit value is less than 2 (in which case the default
944 is "\*STDOUT").
945 You cannot tie this routine directly to an option, e.g.:
947 GetOptions("version" => \&VersionMessage);
949 Use this instead:
951 GetOptions("version" => sub { VersionMessage() });
953 HelpMessage
955 This subroutine produces a standard help message, derived from the
956 program's POD section SYNOPSIS using Pod::Usage. It takes the same
957 arguments as VersionMessage(). In particular, you cannot tie it
958 directly to an option, e.g.:
959 GetOptions("help" => \&HelpMessage);
961 Use this instead:
963 GetOptions("help" => sub { HelpMessage() });
965
967 Configuration errors and errors in the option definitions are signalled
968 using die() and will terminate the calling program unless the call to
969 Getopt::Long::GetOptions() was embedded in "eval { ... }", or die()
970 was trapped using $SIG{__DIE__}.
971 GetOptions returns true to indicate success. It returns false when the
973 function detected one or more errors during option parsing. These
974 errors are signalled using warn() and can be trapped with
975 $SIG{__WARN__}.
976
978 The earliest development of "newgetopt.pl" started in 1990, with Perl
979 version 4. As a result, its development, and the development of
980 Getopt::Long, has gone through several stages. Since backward
981 compatibility has always been extremely important, the current version
982 of Getopt::Long still supports a lot of constructs that nowadays are no
983 longer necessary or otherwise unwanted. This section describes briefly
984 some of these 'features'.
985 Default destinations
987 When no destination is specified for an option, GetOptions will store
988 the resultant value in a global variable named "opt_"XXX, where XXX is
989 the primary name of this option. When a program executes under "use
990 strict" (recommended), these variables must be pre-declared with our()
991 or "use vars".
992 our $opt_length = 0;
994 GetOptions ('length=i'); # will store in $opt_length
995 To yield a usable Perl variable, characters that are not part of the
997 syntax for variables are translated to underscores. For example,
998 "--fpp-struct-return" will set the variable $opt_fpp_struct_return.
999 Note that this variable resides in the namespace of the calling
1000 program, not necessarily "main". For example:
1001 GetOptions ("size=i", "sizes=i@");
1003 with command line "-size 10 -sizes 24 -sizes 48" will perform the
1005 equivalent of the assignments
1006 $opt_size = 10;
1008 @opt_sizes = (24, 48);
1009 Alternative option starters
1011 A string of alternative option starter characters may be passed as the
1012 first argument (or the first argument after a leading hash reference
1013 argument).
1014 my $len = 0;
1016 GetOptions ('/', 'length=i' => $len);
1017 Now the command line may look like:
1019 /length 24 -- arg
1021 Note that to terminate options processing still requires a double dash
1023 "--".
1024 GetOptions() will not interpret a leading "<>" as option starters if
1026 the next argument is a reference. To force "<" and ">" as option
1027 starters, use "><". Confusing? Well, using a starter argument is
1028 strongly deprecated anyway.
1029 Configuration variables
1031 Previous versions of Getopt::Long used variables for the purpose of
1032 configuring. Although manipulating these variables still work, it is
1033 strongly encouraged to use the "Configure" routine that was introduced
1034 in version 2.17. Besides, it is much easier.
1035
1037 Pushing multiple values in a hash option
1038 Sometimes you want to combine the best of hashes and arrays. For
1039 example, the command line:
1040 --list add=first --list add=second --list add=third
1042 where each successive 'list add' option will push the value of add into
1044 array ref $list->{'add'}. The result would be like
1045 $list->{add} = [qw(first second third)];
1047 This can be accomplished with a destination routine:
1049 GetOptions('list=s%' =>
1051 sub { push(@{$list{$_[1]}}, $_[2]) });
1052
1054 GetOptions does not return a false result when an option is not supplied
1055 That's why they're called 'options'.
1056 GetOptions does not split the command line correctly
1058 The command line is not split by GetOptions, but by the command line
1059 interpreter (CLI). On Unix, this is the shell. On Windows, it is
1060 COMMAND.COM or CMD.EXE. Other operating systems have other CLIs.
1061 It is important to know that these CLIs may behave different when the
1063 command line contains special characters, in particular quotes or
1064 backslashes. For example, with Unix shells you can use single quotes
1065 ("'") and double quotes (""") to group words together. The following
1066 alternatives are equivalent on Unix:
1067 "two words"
1069 'two words'
1070 two\ words
1071 In case of doubt, insert the following statement in front of your Perl
1073 program:
1074 print STDERR (join("|",@ARGV),"\n");
1076 to verify how your CLI passes the arguments to the program.
1078 Undefined subroutine &main::GetOptions called
1080 Are you running Windows, and did you write
1081 use GetOpt::Long;
1083 (note the capital 'O')?
1085 How do I put a "-?" option into a Getopt::Long?
1087 You can only obtain this using an alias, and Getopt::Long of at least
1088 version 2.13.
1089 use Getopt::Long;
1091 GetOptions ("help|?"); # -help and -? will both set $opt_help
1092 Other characters that can't appear in Perl identifiers are also
1094 supported in aliases with Getopt::Long of at version 2.39. Note that
1095 the characters "!", "|", "+", "=", and ":" can only appear as the first
1096 (or only) character of an alias.
1097 As of version 2.32 Getopt::Long provides auto-help, a quick and easy
1099 way to add the options --help and -? to your program, and handle them.
1100 See "auto_help" in section "Configuring Getopt::Long".
1102
1104 Johan Vromans <jvromans@squirrel.nl>
1105
1107 This program is Copyright 1990,2015 by Johan Vromans. This program is
1108 free software; you can redistribute it and/or modify it under the terms
1109 of the Perl Artistic License or the GNU General Public License as
1110 published by the Free Software Foundation; either version 2 of the
1111 License, or (at your option) any later version.
1112 This program is distributed in the hope that it will be useful, but
1114 WITHOUT ANY WARRANTY; without even the implied warranty of
1115 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
1116 General Public License for more details.
1117 If you do not have a copy of the GNU General Public License write to
1119 the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139,
1120 USA.
1121perl v5.36.0 2023-01-20 Getopt::Long(3)