1Getopt::Long(3pm) Perl Programmers Reference Guide Getopt::Long(3pm)
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 $result = GetOptions ("length=i" => \$length, # numeric
14 "file=s" => \$data, # string
15 "verbose" => \$verbose); # flag
16
18 The Getopt::Long module implements an extended getopt function called
19 GetOptions(). This function adheres to the POSIX syntax for command
20 line options, with GNU extensions. In general, this means that options
21 have long names instead of single letters, and are introduced with a
22 double dash "--". Support for bundling of command line options, as was
23 the case with the more traditional single-letter approach, is provided
24 but not enabled by default.
25
27 Command line operated programs traditionally take their arguments from
28 the command line, for example filenames or other information that the
29 program needs to know. Besides arguments, these programs often take
30 command line options as well. Options are not necessary for the program
31 to work, hence the name 'option', but are used to modify its default
32 behaviour. For example, a program could do its job quietly, but with a
33 suitable option it could provide verbose information about what it did.
34 Command line options come in several flavours. Historically, they are
36 preceded by a single dash "-", and consist of a single letter.
37 -l -a -c
39 Usually, these single-character options can be bundled:
41 -lac
43 Options can have values, the value is placed after the option
45 character. Sometimes with whitespace in between, sometimes not:
46 -s 24 -s24
48 Due to the very cryptic nature of these options, another style was
50 developed that used long names. So instead of a cryptic "-l" one could
51 use the more descriptive "--long". To distinguish between a bundle of
52 single-character options and a long one, two dashes are used to precede
53 the option name. Early implementations of long options used a plus "+"
54 instead. Also, option values could be specified either like
55 --size=24
57 or
59 --size 24
61 The "+" form is now obsolete and strongly deprecated.
63
65 Getopt::Long is the Perl5 successor of "newgetopt.pl". This was the
66 first Perl module that provided support for handling the new style of
67 command line options, hence the name Getopt::Long. This module also
68 supports single-character options and bundling. Single character
69 options may be any alphabetic character, a question mark, and a dash.
70 Long options may consist of a series of letters, digits, and dashes.
71 Although this is currently not enforced by Getopt::Long, multiple
72 consecutive dashes are not allowed, and the option name must not end
73 with a dash.
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 to
115 STDERR, 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 An incremental option is specified with a plus "+" after the option
134 name:
135 my $verbose = ''; # option variable with default value (false)
137 GetOptions ('verbose+' => \$verbose);
138 Using "--verbose" on the command line will increment the value of
140 $verbose. This way the program can keep track of how many times the
141 option occurred on the command line. For example, each occurrence of
142 "--verbose" could increase the verbosity level of the program.
143 Mixing command line option with other arguments
145 Usually programs take command line options as well as other arguments,
146 for example, file names. It is good practice to always specify the
147 options first, and the other arguments last. Getopt::Long will,
148 however, allow the options and arguments to be mixed and 'filter out'
149 all the options before passing the rest of the arguments to the
150 program. To stop Getopt::Long from processing further arguments, insert
151 a double dash "--" on the command line:
152 --size 24 -- --all
154 In this example, "--all" will not be treated as an option, but passed
156 to the program unharmed, in @ARGV.
157 Options with values
159 For options that take values it must be specified whether the option
160 value is required or not, and what kind of value the option expects.
161 Three kinds of values are supported: integer numbers, floating point
163 numbers, and strings.
164 If the option value is required, Getopt::Long will take the command
166 line argument that follows the option and assign this to the option
167 variable. If, however, the option value is specified as optional, this
168 will only be done if that value does not look like a valid command line
169 option itself.
170 my $tag = ''; # option variable with default value
172 GetOptions ('tag=s' => \$tag);
173 In the option specification, the option name is followed by an equals
175 sign "=" and the letter "s". The equals sign indicates that this option
176 requires a value. The letter "s" indicates that this value is an
177 arbitrary string. Other possible value types are "i" for integer
178 values, and "f" for floating point values. Using a colon ":" instead of
179 the equals sign indicates that the option value is optional. In this
180 case, if no suitable value is supplied, string valued options get an
181 empty string '' assigned, while numeric options are set to 0.
182 Options with multiple values
184 Options sometimes take several values. For example, a program could use
185 multiple directories to search for library files:
186 --library lib/stdlib --library lib/extlib
188 To accomplish this behaviour, simply specify an array reference as the
190 destination for the option:
191 GetOptions ("library=s" => \@libfiles);
193 Alternatively, you can specify that the option can have multiple values
195 by adding a "@", and pass a scalar reference as the destination:
196 GetOptions ("library=s@" => \$libfiles);
198 Used with the example above, @libfiles (or @$libfiles) would contain
200 two strings upon completion: "lib/srdlib" and "lib/extlib", in that
201 order. It is also possible to specify that only integer or floating
202 point numbers are acceptable values.
203 Often it is useful to allow comma-separated lists of values as well as
205 multiple occurrences of the options. This is easy using Perl's split()
206 and join() operators:
207 GetOptions ("library=s" => \@libfiles);
209 @libfiles = split(/,/,join(',',@libfiles));
210 Of course, it is important to choose the right separator string for
212 each purpose.
213 Warning: What follows is an experimental feature.
215 Options can take multiple values at once, for example
217 --coordinates 52.2 16.4 --rgbcolor 255 255 149
219 This can be accomplished by adding a repeat specifier to the option
221 specification. Repeat specifiers are very similar to the "{...}" repeat
222 specifiers that can be used with regular expression patterns. For
223 example, the above command line would be handled as follows:
224 GetOptions('coordinates=f{2}' => \@coor, 'rgbcolor=i{3}' => \@color);
226 The destination for the option must be an array or array reference.
228 It is also possible to specify the minimal and maximal number of
230 arguments an option takes. "foo=s{2,4}" indicates an option that takes
231 at least two and at most 4 arguments. "foo=s{,}" indicates one or more
232 values; "foo:s{,}" indicates zero or more option values.
233 Options with hash values
235 If the option destination is a reference to a hash, the option will
236 take, as value, strings of the form key"="value. The value will be
237 stored with the specified key in the hash.
238 GetOptions ("define=s" => \%defines);
240 Alternatively you can use:
242 GetOptions ("define=s%" => \$defines);
244 When used with command line options:
246 --define os=linux --define vendor=redhat
248 the hash %defines (or %$defines) will contain two keys, "os" with value
250 "linux" and "vendor" with value "redhat". It is also possible to
251 specify that only integer or floating point numbers are acceptable
252 values. The keys are always taken to be strings.
253 User-defined subroutines to handle options
255 Ultimate control over what should be done when (actually: each time) an
256 option is encountered on the command line can be achieved by
257 designating a reference to a subroutine (or an anonymous subroutine) as
258 the option destination. When GetOptions() encounters the option, it
259 will call the subroutine with two or three arguments. The first
260 argument is the name of the option. (Actually, it is an object that
261 stringifies to the name of the option.) For a scalar or array
262 destination, the second argument is the value to be stored. For a hash
263 destination, the second arguments is the key to the hash, and the third
264 argument the value to be stored. It is up to the subroutine to store
265 the value, or do whatever it thinks is appropriate.
266 A trivial application of this mechanism is to implement options that
268 are related to each other. For example:
269 my $verbose = ''; # option variable with default value (false)
271 GetOptions ('verbose' => \$verbose,
272 'quiet' => sub { $verbose = 0 });
273 Here "--verbose" and "--quiet" control the same variable $verbose, but
275 with opposite values.
276 If the subroutine needs to signal an error, it should call die() with
278 the desired error message as its argument. GetOptions() will catch the
279 die(), issue the error message, and record that an error result must be
280 returned upon completion.
281 If the text of the error message starts with an exclamation mark "!"
283 it is interpreted specially by GetOptions(). There is currently one
284 special command implemented: "die("!FINISH")" will cause GetOptions()
285 to stop processing options, as if it encountered a double dash "--".
286 In version 2.37 the first argument to the callback function was changed
288 from string to object. This was done to make room for extensions and
289 more detailed control. The object stringifies to the option name so
290 this change should not introduce compatibility problems.
291 Options with multiple names
293 Often it is user friendly to supply alternate mnemonic names for
294 options. For example "--height" could be an alternate name for
295 "--length". Alternate names can be included in the option
296 specification, separated by vertical bar "|" characters. To implement
297 the above example:
298 GetOptions ('length|height=f' => \$length);
300 The first name is called the primary name, the other names are called
302 aliases. When using a hash to store options, the key will always be the
303 primary name.
304 Multiple alternate names are possible.
306 Case and abbreviations
308 Without additional configuration, GetOptions() will ignore the case of
309 option names, and allow the options to be abbreviated to uniqueness.
310 GetOptions ('length|height=f' => \$length, "head" => \$head);
312 This call will allow "--l" and "--L" for the length option, but
314 requires a least "--hea" and "--hei" for the head and height options.
315 Summary of Option Specifications
317 Each option specifier consists of two parts: the name specification and
318 the argument specification.
319 The name specification contains the name of the option, optionally
321 followed by a list of alternative names separated by vertical bar
322 characters.
323 length option name is "length"
325 length|size|l name is "length", aliases are "size" and "l"
326 The argument specification is optional. If omitted, the option is
328 considered boolean, a value of 1 will be assigned when the option is
329 used on the command line.
330 The argument specification can be
332 ! The option does not take an argument and may be negated by
334 prefixing it with "no" or "no-". E.g. "foo!" will allow "--foo" (a
335 value of 1 will be assigned) as well as "--nofoo" and "--no-foo" (a
336 value of 0 will be assigned). If the option has aliases, this
337 applies to the aliases as well.
338 Using negation on a single letter option when bundling is in effect
340 is pointless and will result in a warning.
341 + The option does not take an argument and will be incremented by 1
343 every time it appears on the command line. E.g. "more+", when used
344 with "--more --more --more", will increment the value three times,
345 resulting in a value of 3 (provided it was 0 or undefined at
346 first).
347 The "+" specifier is ignored if the option destination is not a
349 scalar.
350 = type [ desttype ] [ repeat ]
352 The option requires an argument of the given type. Supported types
353 are:
354 s String. An arbitrary sequence of characters. It is valid for
356 the argument to start with "-" or "--".
357 i Integer. An optional leading plus or minus sign, followed by a
359 sequence of digits.
360 o Extended integer, Perl style. This can be either an optional
362 leading plus or minus sign, followed by a sequence of digits,
363 or an octal string (a zero, optionally followed by '0', '1', ..
364 '7'), or a hexadecimal string ("0x" followed by '0' .. '9', 'a'
365 .. 'f', case insensitive), or a binary string ("0b" followed by
366 a series of '0' and '1').
367 f Real number. For example 3.14, "-6.23E24" and so on.
369 The desttype can be "@" or "%" to specify that the option is list
371 or a hash valued. This is only needed when the destination for the
372 option value is not otherwise specified. It should be omitted when
373 not needed.
374 The repeat specifies the number of values this option takes per
376 occurrence on the command line. It has the format "{" [ min ] [ ","
377 [ max ] ] "}".
378 min denotes the minimal number of arguments. It defaults to 1 for
380 options with "=" and to 0 for options with ":", see below. Note
381 that min overrules the "=" / ":" semantics.
382 max denotes the maximum number of arguments. It must be at least
384 min. If max is omitted, but the comma is not, there is no upper
385 bound to the number of argument values taken.
386 : type [ desttype ]
388 Like "=", but designates the argument as optional. If omitted, an
389 empty string will be assigned to string values options, and the
390 value zero to numeric options.
391 Note that if a string argument starts with "-" or "--", it will be
393 considered an option on itself.
394 : number [ desttype ]
396 Like ":i", but if the value is omitted, the number will be
397 assigned.
398 : + [ desttype ]
400 Like ":i", but if the value is omitted, the current value for the
401 option will be incremented.
402
404 Object oriented interface
405 Getopt::Long can be used in an object oriented way as well:
406 use Getopt::Long;
408 $p = new Getopt::Long::Parser;
409 $p->configure(...configuration options...);
410 if ($p->getoptions(...options descriptions...)) ...
411 Configuration options can be passed to the constructor:
413 $p = new Getopt::Long::Parser
415 config => [...configuration options...];
416 Thread Safety
418 Getopt::Long is thread safe when using ithreads as of Perl 5.8. It is
419 not thread safe when using the older (experimental and now obsolete)
420 threads implementation that was added to Perl 5.005.
421 Documentation and help texts
423 Getopt::Long encourages the use of Pod::Usage to produce help messages.
424 For example:
425 use Getopt::Long;
427 use Pod::Usage;
428 my $man = 0;
430 my $help = 0;
431 GetOptions('help|?' => \$help, man => \$man) or pod2usage(2);
433 pod2usage(1) if $help;
434 pod2usage(-exitstatus => 0, -verbose => 2) if $man;
435 __END__
437 =head1 NAME
439 sample - Using Getopt::Long and Pod::Usage
441 =head1 SYNOPSIS
443 sample [options] [file ...]
445 Options:
447 -help brief help message
448 -man full documentation
449 =head1 OPTIONS
451 =over 8
453 =item B<-help>
455 Print a brief help message and exits.
457 =item B<-man>
459 Prints the manual page and exits.
461 =back
463 =head1 DESCRIPTION
465 B<This program> will read the given input file(s) and do something
467 useful with the contents thereof.
468 =cut
470 See Pod::Usage for details.
472 Parsing options from an arbitrary array
474 By default, GetOptions parses the options that are present in the
475 global array @ARGV. A special entry "GetOptionsFromArray" can be used
476 to parse options from an arbitrary array.
477 use Getopt::Long qw(GetOptionsFromArray);
479 $ret = GetOptionsFromArray(\@myopts, ...);
480 When used like this, the global @ARGV is not touched at all.
482 The following two calls behave identically:
484 $ret = GetOptions( ... );
486 $ret = GetOptionsFromArray(\@ARGV, ... );
487 Parsing options from an arbitrary string
489 A special entry "GetOptionsFromString" can be used to parse options
490 from an arbitrary string.
491 use Getopt::Long qw(GetOptionsFromString);
493 $ret = GetOptionsFromString($string, ...);
494 The contents of the string are split into arguments using a call to
496 "Text::ParseWords::shellwords". As with "GetOptionsFromArray", the
497 global @ARGV is not touched.
498 It is possible that, upon completion, not all arguments in the string
500 have been processed. "GetOptionsFromString" will, when called in list
501 context, return both the return status and an array reference to any
502 remaining arguments:
503 ($ret, $args) = GetOptionsFromString($string, ... );
505 If any arguments remain, and "GetOptionsFromString" was not called in
507 list context, a message will be given and "GetOptionsFromString" will
508 return failure.
509 Storing options values in a hash
511 Sometimes, for example when there are a lot of options, having a
512 separate variable for each of them can be cumbersome. GetOptions()
513 supports, as an alternative mechanism, storing options values in a
514 hash.
515 To obtain this, a reference to a hash must be passed as the first
517 argument to GetOptions(). For each option that is specified on the
518 command line, the option value will be stored in the hash with the
519 option name as key. Options that are not actually used on the command
520 line will not be put in the hash, on other words, "exists($h{option})"
521 (or defined()) can be used to test if an option was used. The drawback
522 is that warnings will be issued if the program runs under "use strict"
523 and uses $h{option} without testing with exists() or defined() first.
524 my %h = ();
526 GetOptions (\%h, 'length=i'); # will store in $h{length}
527 For options that take list or hash values, it is necessary to indicate
529 this by appending an "@" or "%" sign after the type:
530 GetOptions (\%h, 'colours=s@'); # will push to @{$h{colours}}
532 To make things more complicated, the hash may contain references to the
534 actual destinations, for example:
535 my $len = 0;
537 my %h = ('length' => \$len);
538 GetOptions (\%h, 'length=i'); # will store in $len
539 This example is fully equivalent with:
541 my $len = 0;
543 GetOptions ('length=i' => \$len); # will store in $len
544 Any mixture is possible. For example, the most frequently used options
546 could be stored in variables while all other options get stored in the
547 hash:
548 my $verbose = 0; # frequently referred
550 my $debug = 0; # frequently referred
551 my %h = ('verbose' => \$verbose, 'debug' => \$debug);
552 GetOptions (\%h, 'verbose', 'debug', 'filter', 'size=i');
553 if ( $verbose ) { ... }
554 if ( exists $h{filter} ) { ... option 'filter' was specified ... }
555 Bundling
557 With bundling it is possible to set several single-character options at
558 once. For example if "a", "v" and "x" are all valid options,
559 -vax
561 would set all three.
563 Getopt::Long supports two levels of bundling. To enable bundling, a
565 call to Getopt::Long::Configure is required.
566 The first level of bundling can be enabled with:
568 Getopt::Long::Configure ("bundling");
570 Configured this way, single-character options can be bundled but long
572 options must always start with a double dash "--" to avoid ambiguity.
573 For example, when "vax", "a", "v" and "x" are all valid options,
574 -vax
576 would set "a", "v" and "x", but
578 --vax
580 would set "vax".
582 The second level of bundling lifts this restriction. It can be enabled
584 with:
585 Getopt::Long::Configure ("bundling_override");
587 Now, "-vax" would set the option "vax".
589 When any level of bundling is enabled, option values may be inserted in
591 the bundle. For example:
592 -h24w80
594 is equivalent to
596 -h 24 -w 80
598 When configured for bundling, single-character options are matched case
600 sensitive while long options are matched case insensitive. To have the
601 single-character options matched case insensitive as well, use:
602 Getopt::Long::Configure ("bundling", "ignorecase_always");
604 It goes without saying that bundling can be quite confusing.
606 The lonesome dash
608 Normally, a lone dash "-" on the command line will not be considered an
609 option. Option processing will terminate (unless "permute" is
610 configured) and the dash will be left in @ARGV.
611 It is possible to get special treatment for a lone dash. This can be
613 achieved by adding an option specification with an empty name, for
614 example:
615 GetOptions ('' => \$stdio);
617 A lone dash on the command line will now be a legal option, and using
619 it will set variable $stdio.
620 Argument callback
622 A special option 'name' "<>" can be used to designate a subroutine to
623 handle non-option arguments. When GetOptions() encounters an argument
624 that does not look like an option, it will immediately call this
625 subroutine and passes it one parameter: the argument name. Well,
626 actually it is an object that stringifies to the argument name.
627 For example:
629 my $width = 80;
631 sub process { ... }
632 GetOptions ('width=i' => \$width, '<>' => \&process);
633 When applied to the following command line:
635 arg1 --width=72 arg2 --width=60 arg3
637 This will call "process("arg1")" while $width is 80, "process("arg2")"
639 while $width is 72, and "process("arg3")" while $width is 60.
640 This feature requires configuration option permute, see section
642 "Configuring Getopt::Long".
643
645 Getopt::Long can be configured by calling subroutine
646 Getopt::Long::Configure(). This subroutine takes a list of quoted
647 strings, each specifying a configuration option to be enabled, e.g.
648 "ignore_case", or disabled, e.g. "no_ignore_case". Case does not
649 matter. Multiple calls to Configure() are possible.
650 Alternatively, as of version 2.24, the configuration options may be
652 passed together with the "use" statement:
653 use Getopt::Long qw(:config no_ignore_case bundling);
655 The following options are available:
657 default This option causes all configuration options to be reset to
659 their default values.
660 posix_default
662 This option causes all configuration options to be reset to
663 their default values as if the environment variable
664 POSIXLY_CORRECT had been set.
665 auto_abbrev Allow option names to be abbreviated to uniqueness.
667 Default is enabled unless environment variable
668 POSIXLY_CORRECT has been set, in which case "auto_abbrev"
669 is disabled.
670 getopt_compat
672 Allow "+" to start options. Default is enabled unless
673 environment variable POSIXLY_CORRECT has been set, in which
674 case "getopt_compat" is disabled.
675 gnu_compat "gnu_compat" controls whether "--opt=" is allowed, and what
677 it should do. Without "gnu_compat", "--opt=" gives an
678 error. With "gnu_compat", "--opt=" will give option "opt"
679 and empty value. This is the way GNU getopt_long() does
680 it.
681 gnu_getopt This is a short way of setting "gnu_compat" "bundling"
683 "permute" "no_getopt_compat". With "gnu_getopt", command
684 line handling should be fully compatible with GNU
685 getopt_long().
686 require_order
688 Whether command line arguments are allowed to be mixed with
689 options. Default is disabled unless environment variable
690 POSIXLY_CORRECT has been set, in which case "require_order"
691 is enabled.
692 See also "permute", which is the opposite of
694 "require_order".
695 permute Whether command line arguments are allowed to be mixed with
697 options. Default is enabled unless environment variable
698 POSIXLY_CORRECT has been set, in which case "permute" is
699 disabled. Note that "permute" is the opposite of
700 "require_order".
701 If "permute" is enabled, this means that
703 --foo arg1 --bar arg2 arg3
705 is equivalent to
707 --foo --bar arg1 arg2 arg3
709 If an argument callback routine is specified, @ARGV will
711 always be empty upon successful return of GetOptions()
712 since all options have been processed. The only exception
713 is when "--" is used:
714 --foo arg1 --bar arg2 -- arg3
716 This will call the callback routine for arg1 and arg2, and
718 then terminate GetOptions() leaving "arg3" in @ARGV.
719 If "require_order" is enabled, options processing
721 terminates when the first non-option is encountered.
722 --foo arg1 --bar arg2 arg3
724 is equivalent to
726 --foo -- arg1 --bar arg2 arg3
728 If "pass_through" is also enabled, options processing will
730 terminate at the first unrecognized option, or non-option,
731 whichever comes first.
732 bundling (default: disabled)
734 Enabling this option will allow single-character options to
735 be bundled. To distinguish bundles from long option names,
736 long options must be introduced with "--" and bundles with
737 "-".
738 Note that, if you have options "a", "l" and "all", and
740 auto_abbrev enabled, possible arguments and option settings
741 are:
742 using argument sets option(s)
744 ------------------------------------------
745 -a, --a a
746 -l, --l l
747 -al, -la, -ala, -all,... a, l
748 --al, --all all
749 The surprising part is that "--a" sets option "a" (due to
751 auto completion), not "all".
752 Note: disabling "bundling" also disables
754 "bundling_override".
755 bundling_override (default: disabled)
757 If "bundling_override" is enabled, bundling is enabled as
758 with "bundling" but now long option names override option
759 bundles.
760 Note: disabling "bundling_override" also disables
762 "bundling".
763 Note: Using option bundling can easily lead to unexpected
765 results, especially when mixing long options and bundles.
766 Caveat emptor.
767 ignore_case (default: enabled)
769 If enabled, case is ignored when matching long option
770 names. If, however, bundling is enabled as well, single
771 character options will be treated case-sensitive.
772 With "ignore_case", option specifications for options that
774 only differ in case, e.g., "foo" and "Foo", will be flagged
775 as duplicates.
776 Note: disabling "ignore_case" also disables
778 "ignore_case_always".
779 ignore_case_always (default: disabled)
781 When bundling is in effect, case is ignored on single-
782 character options also.
783 Note: disabling "ignore_case_always" also disables
785 "ignore_case".
786 auto_version (default:disabled)
788 Automatically provide support for the --version option if
789 the application did not specify a handler for this option
790 itself.
791 Getopt::Long will provide a standard version message that
793 includes the program name, its version (if $main::VERSION
794 is defined), and the versions of Getopt::Long and Perl. The
795 message will be written to standard output and processing
796 will terminate.
797 "auto_version" will be enabled if the calling program
799 explicitly specified a version number higher than 2.32 in
800 the "use" or "require" statement.
801 auto_help (default:disabled)
803 Automatically provide support for the --help and -? options
804 if the application did not specify a handler for this
805 option itself.
806 Getopt::Long will provide a help message using module
808 Pod::Usage. The message, derived from the SYNOPSIS POD
809 section, will be written to standard output and processing
810 will terminate.
811 "auto_help" will be enabled if the calling program
813 explicitly specified a version number higher than 2.32 in
814 the "use" or "require" statement.
815 pass_through (default: disabled)
817 Options that are unknown, ambiguous or supplied with an
818 invalid option value are passed through in @ARGV instead of
819 being flagged as errors. This makes it possible to write
820 wrapper scripts that process only part of the user supplied
821 command line arguments, and pass the remaining options to
822 some other program.
823 If "require_order" is enabled, options processing will
825 terminate at the first unrecognized option, or non-option,
826 whichever comes first. However, if "permute" is enabled
827 instead, results can become confusing.
828 Note that the options terminator (default "--"), if
830 present, will also be passed through in @ARGV.
831 prefix The string that starts options. If a constant string is not
833 sufficient, see "prefix_pattern".
834 prefix_pattern
836 A Perl pattern that identifies the strings that introduce
837 options. Default is "--|-|\+" unless environment variable
838 POSIXLY_CORRECT has been set, in which case it is "--|-".
839 long_prefix_pattern
841 A Perl pattern that allows the disambiguation of long and
842 short prefixes. Default is "--".
843 Typically you only need to set this if you are using
845 nonstandard prefixes and want some or all of them to have
846 the same semantics as '--' does under normal circumstances.
847 For example, setting prefix_pattern to "--|-|\+|\/" and
849 long_prefix_pattern to "--|\/" would add Win32 style
850 argument handling.
851 debug (default: disabled)
853 Enable debugging output.
854
856 VersionMessage
857 This subroutine provides a standard version message. Its argument
858 can be:
859 · A string containing the text of a message to print before
861 printing the standard message.
862 · A numeric value corresponding to the desired exit status.
864 · A reference to a hash.
866 If more than one argument is given then the entire argument list is
868 assumed to be a hash. If a hash is supplied (either as a reference
869 or as a list) it should contain one or more elements with the
870 following keys:
871 "-message"
873 "-msg"
874 The text of a message to print immediately prior to printing
875 the program's usage message.
876 "-exitval"
878 The desired exit status to pass to the exit() function. This
879 should be an integer, or else the string "NOEXIT" to indicate
880 that control should simply be returned without terminating the
881 invoking process.
882 "-output"
884 A reference to a filehandle, or the pathname of a file to which
885 the usage message should be written. The default is "\*STDERR"
886 unless the exit value is less than 2 (in which case the default
887 is "\*STDOUT").
888 You cannot tie this routine directly to an option, e.g.:
890 GetOptions("version" => \&VersionMessage);
892 Use this instead:
894 GetOptions("version" => sub { VersionMessage() });
896 HelpMessage
898 This subroutine produces a standard help message, derived from the
899 program's POD section SYNOPSIS using Pod::Usage. It takes the same
900 arguments as VersionMessage(). In particular, you cannot tie it
901 directly to an option, e.g.:
902 GetOptions("help" => \&HelpMessage);
904 Use this instead:
906 GetOptions("help" => sub { HelpMessage() });
908
910 Configuration errors and errors in the option definitions are signalled
911 using die() and will terminate the calling program unless the call to
912 Getopt::Long::GetOptions() was embedded in "eval { ... }", or die()
913 was trapped using $SIG{__DIE__}.
914 GetOptions returns true to indicate success. It returns false when the
916 function detected one or more errors during option parsing. These
917 errors are signalled using warn() and can be trapped with
918 $SIG{__WARN__}.
919
921 The earliest development of "newgetopt.pl" started in 1990, with Perl
922 version 4. As a result, its development, and the development of
923 Getopt::Long, has gone through several stages. Since backward
924 compatibility has always been extremely important, the current version
925 of Getopt::Long still supports a lot of constructs that nowadays are no
926 longer necessary or otherwise unwanted. This section describes briefly
927 some of these 'features'.
928 Default destinations
930 When no destination is specified for an option, GetOptions will store
931 the resultant value in a global variable named "opt_"XXX, where XXX is
932 the primary name of this option. When a progam executes under "use
933 strict" (recommended), these variables must be pre-declared with our()
934 or "use vars".
935 our $opt_length = 0;
937 GetOptions ('length=i'); # will store in $opt_length
938 To yield a usable Perl variable, characters that are not part of the
940 syntax for variables are translated to underscores. For example,
941 "--fpp-struct-return" will set the variable $opt_fpp_struct_return.
942 Note that this variable resides in the namespace of the calling
943 program, not necessarily "main". For example:
944 GetOptions ("size=i", "sizes=i@");
946 with command line "-size 10 -sizes 24 -sizes 48" will perform the
948 equivalent of the assignments
949 $opt_size = 10;
951 @opt_sizes = (24, 48);
952 Alternative option starters
954 A string of alternative option starter characters may be passed as the
955 first argument (or the first argument after a leading hash reference
956 argument).
957 my $len = 0;
959 GetOptions ('/', 'length=i' => $len);
960 Now the command line may look like:
962 /length 24 -- arg
964 Note that to terminate options processing still requires a double dash
966 "--".
967 GetOptions() will not interpret a leading "<>" as option starters if
969 the next argument is a reference. To force "<" and ">" as option
970 starters, use "><". Confusing? Well, using a starter argument is
971 strongly deprecated anyway.
972 Configuration variables
974 Previous versions of Getopt::Long used variables for the purpose of
975 configuring. Although manipulating these variables still work, it is
976 strongly encouraged to use the "Configure" routine that was introduced
977 in version 2.17. Besides, it is much easier.
978
980 Pushing multiple values in a hash option
981 Sometimes you want to combine the best of hashes and arrays. For
982 example, the command line:
983 --list add=first --list add=second --list add=third
985 where each successive 'list add' option will push the value of add into
987 array ref $list->{'add'}. The result would be like
988 $list->{add} = [qw(first second third)];
990 This can be accomplished with a destination routine:
992 GetOptions('list=s%' =>
994 sub { push(@{$list{$_[1]}}, $_[2]) });
995
997 GetOptions does not return a false result when an option is not supplied
998 That's why they're called 'options'.
999 GetOptions does not split the command line correctly
1001 The command line is not split by GetOptions, but by the command line
1002 interpreter (CLI). On Unix, this is the shell. On Windows, it is
1003 COMMAND.COM or CMD.EXE. Other operating systems have other CLIs.
1004 It is important to know that these CLIs may behave different when the
1006 command line contains special characters, in particular quotes or
1007 backslashes. For example, with Unix shells you can use single quotes
1008 ("'") and double quotes (""") to group words together. The following
1009 alternatives are equivalent on Unix:
1010 "two words"
1012 'two words'
1013 two\ words
1014 In case of doubt, insert the following statement in front of your Perl
1016 program:
1017 print STDERR (join("|",@ARGV),"\n");
1019 to verify how your CLI passes the arguments to the program.
1021 Undefined subroutine &main::GetOptions called
1023 Are you running Windows, and did you write
1024 use GetOpt::Long;
1026 (note the capital 'O')?
1028 How do I put a "-?" option into a Getopt::Long?
1030 You can only obtain this using an alias, and Getopt::Long of at least
1031 version 2.13.
1032 use Getopt::Long;
1034 GetOptions ("help|?"); # -help and -? will both set $opt_help
1035
1037 Johan Vromans <jvromans@squirrel.nl>
1038
1040 This program is Copyright 1990,2009 by Johan Vromans. This program is
1041 free software; you can redistribute it and/or modify it under the terms
1042 of the Perl Artistic License or the GNU General Public License as
1043 published by the Free Software Foundation; either version 2 of the
1044 License, or (at your option) any later version.
1045 This program is distributed in the hope that it will be useful, but
1047 WITHOUT ANY WARRANTY; without even the implied warranty of
1048 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
1049 General Public License for more details.
1050 If you do not have a copy of the GNU General Public License write to
1052 the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139,
1053 USA.
1054perl v5.10.1 2017-03-22 Getopt::Long(3pm)