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 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/stdlib" 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{1,}" 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 argument 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 $verbose, but
275 with opposite values.
276 If the subroutine needs to signal an error, it should call die() with
278 the desired error message as its argument. GetOptions() will catch the
279 die(), issue the error message, and record that an error result must be
280 returned upon completion.
281 If the text of the error message starts with an exclamation mark "!"
283 it is interpreted specially by GetOptions(). There is currently one
284 special command implemented: "die("!FINISH")" will cause GetOptions()
285 to stop processing options, as if it encountered a double dash "--".
286 In version 2.37 the first argument to the callback function was changed
288 from string to object. This was done to make room for extensions and
289 more detailed control. The object stringifies to the option name so
290 this change should not introduce compatibility problems.
291 Here is an example of how to access the option name and value from
293 within a subroutine:
294 GetOptions ('opt=i' => \&handler);
296 sub handler {
297 my ($opt_name, $opt_value) = @_;
298 print("Option name is $opt_name and value is $opt_value\n");
299 }
300 Options with multiple names
302 Often it is user friendly to supply alternate mnemonic names for
303 options. For example "--height" could be an alternate name for
304 "--length". Alternate names can be included in the option
305 specification, separated by vertical bar "|" characters. To implement
306 the above example:
307 GetOptions ('length|height=f' => \$length);
309 The first name is called the primary name, the other names are called
311 aliases. When using a hash to store options, the key will always be the
312 primary name.
313 Multiple alternate names are possible.
315 Case and abbreviations
317 Without additional configuration, GetOptions() will ignore the case of
318 option names, and allow the options to be abbreviated to uniqueness.
319 GetOptions ('length|height=f' => \$length, "head" => \$head);
321 This call will allow "--l" and "--L" for the length option, but
323 requires a least "--hea" and "--hei" for the head and height options.
324 Summary of Option Specifications
326 Each option specifier consists of two parts: the name specification and
327 the argument specification.
328 The name specification contains the name of the option, optionally
330 followed by a list of alternative names separated by vertical bar
331 characters.
332 length option name is "length"
334 length|size|l name is "length", aliases are "size" and "l"
335 The argument specification is optional. If omitted, the option is
337 considered boolean, a value of 1 will be assigned when the option is
338 used on the command line.
339 The argument specification can be
341 ! The option does not take an argument and may be negated by
343 prefixing it with "no" or "no-". E.g. "foo!" will allow "--foo" (a
344 value of 1 will be assigned) as well as "--nofoo" and "--no-foo" (a
345 value of 0 will be assigned). If the option has aliases, this
346 applies to the aliases as well.
347 Using negation on a single letter option when bundling is in effect
349 is pointless and will result in a warning.
350 + The option does not take an argument and will be incremented by 1
352 every time it appears on the command line. E.g. "more+", when used
353 with "--more --more --more", will increment the value three times,
354 resulting in a value of 3 (provided it was 0 or undefined at
355 first).
356 The "+" specifier is ignored if the option destination is not a
358 scalar.
359 = type [ desttype ] [ repeat ]
361 The option requires an argument of the given type. Supported types
362 are:
363 s String. An arbitrary sequence of characters. It is valid for
365 the argument to start with "-" or "--".
366 i Integer. An optional leading plus or minus sign, followed by a
368 sequence of digits.
369 o Extended integer, Perl style. This can be either an optional
371 leading plus or minus sign, followed by a sequence of digits,
372 or an octal string (a zero, optionally followed by '0', '1', ..
373 '7'), or a hexadecimal string ("0x" followed by '0' .. '9', 'a'
374 .. 'f', case insensitive), or a binary string ("0b" followed by
375 a series of '0' and '1').
376 f Real number. For example 3.14, "-6.23E24" and so on.
378 The desttype can be "@" or "%" to specify that the option is list
380 or a hash valued. This is only needed when the destination for the
381 option value is not otherwise specified. It should be omitted when
382 not needed.
383 The repeat specifies the number of values this option takes per
385 occurrence on the command line. It has the format "{" [ min ] [ ","
386 [ max ] ] "}".
387 min denotes the minimal number of arguments. It defaults to 1 for
389 options with "=" and to 0 for options with ":", see below. Note
390 that min overrules the "=" / ":" semantics.
391 max denotes the maximum number of arguments. It must be at least
393 min. If max is omitted, but the comma is not, there is no upper
394 bound to the number of argument values taken.
395 : type [ desttype ]
397 Like "=", but designates the argument as optional. If omitted, an
398 empty string will be assigned to string values options, and the
399 value zero to numeric options.
400 Note that if a string argument starts with "-" or "--", it will be
402 considered an option on itself.
403 : number [ desttype ]
405 Like ":i", but if the value is omitted, the number will be
406 assigned.
407 : + [ desttype ]
409 Like ":i", but if the value is omitted, the current value for the
410 option will be incremented.
411
413 Object oriented interface
414 Getopt::Long can be used in an object oriented way as well:
415 use Getopt::Long;
417 $p = Getopt::Long::Parser->new;
418 $p->configure(...configuration options...);
419 if ($p->getoptions(...options descriptions...)) ...
420 if ($p->getoptionsfromarray( \@array, ...options descriptions...)) ...
421 Configuration options can be passed to the constructor:
423 $p = new Getopt::Long::Parser
425 config => [...configuration options...];
426 Thread Safety
428 Getopt::Long is thread safe when using ithreads as of Perl 5.8. It is
429 not thread safe when using the older (experimental and now obsolete)
430 threads implementation that was added to Perl 5.005.
431 Documentation and help texts
433 Getopt::Long encourages the use of Pod::Usage to produce help messages.
434 For example:
435 use Getopt::Long;
437 use Pod::Usage;
438 my $man = 0;
440 my $help = 0;
441 GetOptions('help|?' => \$help, man => \$man) or pod2usage(2);
443 pod2usage(1) if $help;
444 pod2usage(-exitval => 0, -verbose => 2) if $man;
445 __END__
447 =head1 NAME
449 sample - Using Getopt::Long and Pod::Usage
451 =head1 SYNOPSIS
453 sample [options] [file ...]
455 Options:
457 -help brief help message
458 -man full documentation
459 =head1 OPTIONS
461 =over 8
463 =item B<-help>
465 Print a brief help message and exits.
467 =item B<-man>
469 Prints the manual page and exits.
471 =back
473 =head1 DESCRIPTION
475 B<This program> will read the given input file(s) and do something
477 useful with the contents thereof.
478 =cut
480 See Pod::Usage for details.
482 Parsing options from an arbitrary array
484 By default, GetOptions parses the options that are present in the
485 global array @ARGV. A special entry "GetOptionsFromArray" can be used
486 to parse options from an arbitrary array.
487 use Getopt::Long qw(GetOptionsFromArray);
489 $ret = GetOptionsFromArray(\@myopts, ...);
490 When used like this, options and their possible values are removed from
492 @myopts, the global @ARGV is not touched at all.
493 The following two calls behave identically:
495 $ret = GetOptions( ... );
497 $ret = GetOptionsFromArray(\@ARGV, ... );
498 This also means that a first argument hash reference now becomes the
500 second argument:
501 $ret = GetOptions(\%opts, ... );
503 $ret = GetOptionsFromArray(\@ARGV, \%opts, ... );
504 Parsing options from an arbitrary string
506 A special entry "GetOptionsFromString" can be used to parse options
507 from an arbitrary string.
508 use Getopt::Long qw(GetOptionsFromString);
510 $ret = GetOptionsFromString($string, ...);
511 The contents of the string are split into arguments using a call to
513 "Text::ParseWords::shellwords". As with "GetOptionsFromArray", the
514 global @ARGV is not touched.
515 It is possible that, upon completion, not all arguments in the string
517 have been processed. "GetOptionsFromString" will, when called in list
518 context, return both the return status and an array reference to any
519 remaining arguments:
520 ($ret, $args) = GetOptionsFromString($string, ... );
522 If any arguments remain, and "GetOptionsFromString" was not called in
524 list context, a message will be given and "GetOptionsFromString" will
525 return failure.
526 As with GetOptionsFromArray, a first argument hash reference now
528 becomes the second argument.
529 Storing options values in a hash
531 Sometimes, for example when there are a lot of options, having a
532 separate variable for each of them can be cumbersome. GetOptions()
533 supports, as an alternative mechanism, storing options values in a
534 hash.
535 To obtain this, a reference to a hash must be passed as the first
537 argument to GetOptions(). For each option that is specified on the
538 command line, the option value will be stored in the hash with the
539 option name as key. Options that are not actually used on the command
540 line will not be put in the hash, on other words, "exists($h{option})"
541 (or defined()) can be used to test if an option was used. The drawback
542 is that warnings will be issued if the program runs under "use strict"
543 and uses $h{option} without testing with exists() or defined() first.
544 my %h = ();
546 GetOptions (\%h, 'length=i'); # will store in $h{length}
547 For options that take list or hash values, it is necessary to indicate
549 this by appending an "@" or "%" sign after the type:
550 GetOptions (\%h, 'colours=s@'); # will push to @{$h{colours}}
552 To make things more complicated, the hash may contain references to the
554 actual destinations, for example:
555 my $len = 0;
557 my %h = ('length' => \$len);
558 GetOptions (\%h, 'length=i'); # will store in $len
559 This example is fully equivalent with:
561 my $len = 0;
563 GetOptions ('length=i' => \$len); # will store in $len
564 Any mixture is possible. For example, the most frequently used options
566 could be stored in variables while all other options get stored in the
567 hash:
568 my $verbose = 0; # frequently referred
570 my $debug = 0; # frequently referred
571 my %h = ('verbose' => \$verbose, 'debug' => \$debug);
572 GetOptions (\%h, 'verbose', 'debug', 'filter', 'size=i');
573 if ( $verbose ) { ... }
574 if ( exists $h{filter} ) { ... option 'filter' was specified ... }
575 Bundling
577 With bundling it is possible to set several single-character options at
578 once. For example if "a", "v" and "x" are all valid options,
579 -vax
581 would set all three.
583 Getopt::Long supports two levels of bundling. To enable bundling, a
585 call to Getopt::Long::Configure is required.
586 The first level of bundling can be enabled with:
588 Getopt::Long::Configure ("bundling");
590 Configured this way, single-character options can be bundled but long
592 options must always start with a double dash "--" to avoid ambiguity.
593 For example, when "vax", "a", "v" and "x" are all valid options,
594 -vax
596 would set "a", "v" and "x", but
598 --vax
600 would set "vax".
602 The second level of bundling lifts this restriction. It can be enabled
604 with:
605 Getopt::Long::Configure ("bundling_override");
607 Now, "-vax" would set the option "vax".
609 When any level of bundling is enabled, option values may be inserted in
611 the bundle. For example:
612 -h24w80
614 is equivalent to
616 -h 24 -w 80
618 When configured for bundling, single-character options are matched case
620 sensitive while long options are matched case insensitive. To have the
621 single-character options matched case insensitive as well, use:
622 Getopt::Long::Configure ("bundling", "ignorecase_always");
624 It goes without saying that bundling can be quite confusing.
626 The lonesome dash
628 Normally, a lone dash "-" on the command line will not be considered an
629 option. Option processing will terminate (unless "permute" is
630 configured) and the dash will be left in @ARGV.
631 It is possible to get special treatment for a lone dash. This can be
633 achieved by adding an option specification with an empty name, for
634 example:
635 GetOptions ('' => \$stdio);
637 A lone dash on the command line will now be a legal option, and using
639 it will set variable $stdio.
640 Argument callback
642 A special option 'name' "<>" can be used to designate a subroutine to
643 handle non-option arguments. When GetOptions() encounters an argument
644 that does not look like an option, it will immediately call this
645 subroutine and passes it one parameter: the argument name. Well,
646 actually it is an object that stringifies to the argument name.
647 For example:
649 my $width = 80;
651 sub process { ... }
652 GetOptions ('width=i' => \$width, '<>' => \&process);
653 When applied to the following command line:
655 arg1 --width=72 arg2 --width=60 arg3
657 This will call "process("arg1")" while $width is 80, "process("arg2")"
659 while $width is 72, and "process("arg3")" while $width is 60.
660 This feature requires configuration option permute, see section
662 "Configuring Getopt::Long".
663
665 Getopt::Long can be configured by calling subroutine
666 Getopt::Long::Configure(). This subroutine takes a list of quoted
667 strings, each specifying a configuration option to be enabled, e.g.
668 "ignore_case", or disabled, e.g. "no_ignore_case". Case does not
669 matter. Multiple calls to Configure() are possible.
670 Alternatively, as of version 2.24, the configuration options may be
672 passed together with the "use" statement:
673 use Getopt::Long qw(:config no_ignore_case bundling);
675 The following options are available:
677 default This option causes all configuration options to be reset to
679 their default values.
680 posix_default
682 This option causes all configuration options to be reset to
683 their default values as if the environment variable
684 POSIXLY_CORRECT had been set.
685 auto_abbrev Allow option names to be abbreviated to uniqueness.
687 Default is enabled unless environment variable
688 POSIXLY_CORRECT has been set, in which case "auto_abbrev"
689 is disabled.
690 getopt_compat
692 Allow "+" to start options. Default is enabled unless
693 environment variable POSIXLY_CORRECT has been set, in which
694 case "getopt_compat" is disabled.
695 gnu_compat "gnu_compat" controls whether "--opt=" is allowed, and what
697 it should do. Without "gnu_compat", "--opt=" gives an
698 error. With "gnu_compat", "--opt=" will give option "opt"
699 and empty value. This is the way GNU getopt_long() does
700 it.
701 gnu_getopt This is a short way of setting "gnu_compat" "bundling"
703 "permute" "no_getopt_compat". With "gnu_getopt", command
704 line handling should be fully compatible with GNU
705 getopt_long().
706 require_order
708 Whether command line arguments are allowed to be mixed with
709 options. Default is disabled unless environment variable
710 POSIXLY_CORRECT has been set, in which case "require_order"
711 is enabled.
712 See also "permute", which is the opposite of
714 "require_order".
715 permute Whether command line arguments are allowed to be mixed with
717 options. Default is enabled unless environment variable
718 POSIXLY_CORRECT has been set, in which case "permute" is
719 disabled. Note that "permute" is the opposite of
720 "require_order".
721 If "permute" is enabled, this means that
723 --foo arg1 --bar arg2 arg3
725 is equivalent to
727 --foo --bar arg1 arg2 arg3
729 If an argument callback routine is specified, @ARGV will
731 always be empty upon successful return of GetOptions()
732 since all options have been processed. The only exception
733 is when "--" is used:
734 --foo arg1 --bar arg2 -- arg3
736 This will call the callback routine for arg1 and arg2, and
738 then terminate GetOptions() leaving "arg3" in @ARGV.
739 If "require_order" is enabled, options processing
741 terminates when the first non-option is encountered.
742 --foo arg1 --bar arg2 arg3
744 is equivalent to
746 --foo -- arg1 --bar arg2 arg3
748 If "pass_through" is also enabled, options processing will
750 terminate at the first unrecognized option, or non-option,
751 whichever comes first.
752 bundling (default: disabled)
754 Enabling this option will allow single-character options to
755 be bundled. To distinguish bundles from long option names,
756 long options must be introduced with "--" and bundles with
757 "-".
758 Note that, if you have options "a", "l" and "all", and
760 auto_abbrev enabled, possible arguments and option settings
761 are:
762 using argument sets option(s)
764 ------------------------------------------
765 -a, --a a
766 -l, --l l
767 -al, -la, -ala, -all,... a, l
768 --al, --all all
769 The surprising part is that "--a" sets option "a" (due to
771 auto completion), not "all".
772 Note: disabling "bundling" also disables
774 "bundling_override".
775 bundling_override (default: disabled)
777 If "bundling_override" is enabled, bundling is enabled as
778 with "bundling" but now long option names override option
779 bundles.
780 Note: disabling "bundling_override" also disables
782 "bundling".
783 Note: Using option bundling can easily lead to unexpected
785 results, especially when mixing long options and bundles.
786 Caveat emptor.
787 ignore_case (default: enabled)
789 If enabled, case is ignored when matching option names. If,
790 however, bundling is enabled as well, single character
791 options will be treated case-sensitive.
792 With "ignore_case", option specifications for options that
794 only differ in case, e.g., "foo" and "Foo", will be flagged
795 as duplicates.
796 Note: disabling "ignore_case" also disables
798 "ignore_case_always".
799 ignore_case_always (default: disabled)
801 When bundling is in effect, case is ignored on single-
802 character options also.
803 Note: disabling "ignore_case_always" also disables
805 "ignore_case".
806 auto_version (default:disabled)
808 Automatically provide support for the --version option if
809 the application did not specify a handler for this option
810 itself.
811 Getopt::Long will provide a standard version message that
813 includes the program name, its version (if $main::VERSION
814 is defined), and the versions of Getopt::Long and Perl. The
815 message will be written to standard output and processing
816 will terminate.
817 "auto_version" will be enabled if the calling program
819 explicitly specified a version number higher than 2.32 in
820 the "use" or "require" statement.
821 auto_help (default:disabled)
823 Automatically provide support for the --help and -? options
824 if the application did not specify a handler for this
825 option itself.
826 Getopt::Long will provide a help message using module
828 Pod::Usage. The message, derived from the SYNOPSIS POD
829 section, will be written to standard output and processing
830 will terminate.
831 "auto_help" will be enabled if the calling program
833 explicitly specified a version number higher than 2.32 in
834 the "use" or "require" statement.
835 pass_through (default: disabled)
837 Options that are unknown, ambiguous or supplied with an
838 invalid option value are passed through in @ARGV instead of
839 being flagged as errors. This makes it possible to write
840 wrapper scripts that process only part of the user supplied
841 command line arguments, and pass the remaining options to
842 some other program.
843 If "require_order" is enabled, options processing will
845 terminate at the first unrecognized option, or non-option,
846 whichever comes first. However, if "permute" is enabled
847 instead, results can become confusing.
848 Note that the options terminator (default "--"), if
850 present, will also be passed through in @ARGV.
851 prefix The string that starts options. If a constant string is not
853 sufficient, see "prefix_pattern".
854 prefix_pattern
856 A Perl pattern that identifies the strings that introduce
857 options. Default is "--|-|\+" unless environment variable
858 POSIXLY_CORRECT has been set, in which case it is "--|-".
859 long_prefix_pattern
861 A Perl pattern that allows the disambiguation of long and
862 short prefixes. Default is "--".
863 Typically you only need to set this if you are using
865 nonstandard prefixes and want some or all of them to have
866 the same semantics as '--' does under normal circumstances.
867 For example, setting prefix_pattern to "--|-|\+|\/" and
869 long_prefix_pattern to "--|\/" would add Win32 style
870 argument handling.
871 debug (default: disabled)
873 Enable debugging output.
874
876 VersionMessage
877 This subroutine provides a standard version message. Its argument
878 can be:
879 · A string containing the text of a message to print before
881 printing the standard message.
882 · A numeric value corresponding to the desired exit status.
884 · A reference to a hash.
886 If more than one argument is given then the entire argument list is
888 assumed to be a hash. If a hash is supplied (either as a reference
889 or as a list) it should contain one or more elements with the
890 following keys:
891 "-message"
893 "-msg"
894 The text of a message to print immediately prior to printing
895 the program's usage message.
896 "-exitval"
898 The desired exit status to pass to the exit() function. This
899 should be an integer, or else the string "NOEXIT" to indicate
900 that control should simply be returned without terminating the
901 invoking process.
902 "-output"
904 A reference to a filehandle, or the pathname of a file to which
905 the usage message should be written. The default is "\*STDERR"
906 unless the exit value is less than 2 (in which case the default
907 is "\*STDOUT").
908 You cannot tie this routine directly to an option, e.g.:
910 GetOptions("version" => \&VersionMessage);
912 Use this instead:
914 GetOptions("version" => sub { VersionMessage() });
916 HelpMessage
918 This subroutine produces a standard help message, derived from the
919 program's POD section SYNOPSIS using Pod::Usage. It takes the same
920 arguments as VersionMessage(). In particular, you cannot tie it
921 directly to an option, e.g.:
922 GetOptions("help" => \&HelpMessage);
924 Use this instead:
926 GetOptions("help" => sub { HelpMessage() });
928
930 Configuration errors and errors in the option definitions are signalled
931 using die() and will terminate the calling program unless the call to
932 Getopt::Long::GetOptions() was embedded in "eval { ... }", or die()
933 was trapped using $SIG{__DIE__}.
934 GetOptions returns true to indicate success. It returns false when the
936 function detected one or more errors during option parsing. These
937 errors are signalled using warn() and can be trapped with
938 $SIG{__WARN__}.
939
941 The earliest development of "newgetopt.pl" started in 1990, with Perl
942 version 4. As a result, its development, and the development of
943 Getopt::Long, has gone through several stages. Since backward
944 compatibility has always been extremely important, the current version
945 of Getopt::Long still supports a lot of constructs that nowadays are no
946 longer necessary or otherwise unwanted. This section describes briefly
947 some of these 'features'.
948 Default destinations
950 When no destination is specified for an option, GetOptions will store
951 the resultant value in a global variable named "opt_"XXX, where XXX is
952 the primary name of this option. When a program executes under "use
953 strict" (recommended), these variables must be pre-declared with our()
954 or "use vars".
955 our $opt_length = 0;
957 GetOptions ('length=i'); # will store in $opt_length
958 To yield a usable Perl variable, characters that are not part of the
960 syntax for variables are translated to underscores. For example,
961 "--fpp-struct-return" will set the variable $opt_fpp_struct_return.
962 Note that this variable resides in the namespace of the calling
963 program, not necessarily "main". For example:
964 GetOptions ("size=i", "sizes=i@");
966 with command line "-size 10 -sizes 24 -sizes 48" will perform the
968 equivalent of the assignments
969 $opt_size = 10;
971 @opt_sizes = (24, 48);
972 Alternative option starters
974 A string of alternative option starter characters may be passed as the
975 first argument (or the first argument after a leading hash reference
976 argument).
977 my $len = 0;
979 GetOptions ('/', 'length=i' => $len);
980 Now the command line may look like:
982 /length 24 -- arg
984 Note that to terminate options processing still requires a double dash
986 "--".
987 GetOptions() will not interpret a leading "<>" as option starters if
989 the next argument is a reference. To force "<" and ">" as option
990 starters, use "><". Confusing? Well, using a starter argument is
991 strongly deprecated anyway.
992 Configuration variables
994 Previous versions of Getopt::Long used variables for the purpose of
995 configuring. Although manipulating these variables still work, it is
996 strongly encouraged to use the "Configure" routine that was introduced
997 in version 2.17. Besides, it is much easier.
998
1000 Pushing multiple values in a hash option
1001 Sometimes you want to combine the best of hashes and arrays. For
1002 example, the command line:
1003 --list add=first --list add=second --list add=third
1005 where each successive 'list add' option will push the value of add into
1007 array ref $list->{'add'}. The result would be like
1008 $list->{add} = [qw(first second third)];
1010 This can be accomplished with a destination routine:
1012 GetOptions('list=s%' =>
1014 sub { push(@{$list{$_[1]}}, $_[2]) });
1015
1017 GetOptions does not return a false result when an option is not supplied
1018 That's why they're called 'options'.
1019 GetOptions does not split the command line correctly
1021 The command line is not split by GetOptions, but by the command line
1022 interpreter (CLI). On Unix, this is the shell. On Windows, it is
1023 COMMAND.COM or CMD.EXE. Other operating systems have other CLIs.
1024 It is important to know that these CLIs may behave different when the
1026 command line contains special characters, in particular quotes or
1027 backslashes. For example, with Unix shells you can use single quotes
1028 ("'") and double quotes (""") to group words together. The following
1029 alternatives are equivalent on Unix:
1030 "two words"
1032 'two words'
1033 two\ words
1034 In case of doubt, insert the following statement in front of your Perl
1036 program:
1037 print STDERR (join("|",@ARGV),"\n");
1039 to verify how your CLI passes the arguments to the program.
1041 Undefined subroutine &main::GetOptions called
1043 Are you running Windows, and did you write
1044 use GetOpt::Long;
1046 (note the capital 'O')?
1048 How do I put a "-?" option into a Getopt::Long?
1050 You can only obtain this using an alias, and Getopt::Long of at least
1051 version 2.13.
1052 use Getopt::Long;
1054 GetOptions ("help|?"); # -help and -? will both set $opt_help
1055 Other characters that can't appear in Perl identifiers are also
1057 supported as aliases with Getopt::Long of at least version 2.39.
1058 As of version 2.32 Getopt::Long provides auto-help, a quick and easy
1060 way to add the options --help and -? to your program, and handle them.
1061 See "auto_help" in section "Configuring Getopt::Long".
1063
1065 Johan Vromans <jvromans@squirrel.nl>
1066
1068 This program is Copyright 1990,2013 by Johan Vromans. This program is
1069 free software; you can redistribute it and/or modify it under the terms
1070 of the Perl Artistic License or the GNU General Public License as
1071 published by the Free Software Foundation; either version 2 of the
1072 License, or (at your option) any later version.
1073 This program is distributed in the hope that it will be useful, but
1075 WITHOUT ANY WARRANTY; without even the implied warranty of
1076 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
1077 General Public License for more details.
1078 If you do not have a copy of the GNU General Public License write to
1080 the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139,
1081 USA.
1082perl v5.16.3 2013-06-16 Getopt::Long(3)