Home Man
Search
Today's Posts
Register

Linux & Unix Commands - Search Man Pages

RedHat 9 (Linux i386) - man page for getopt::long (redhat section 3pm)

Getopt::Long(3pm)		 Perl Programmers Reference Guide		Getopt::Long(3pm)

NAME
       Getopt::Long - Extended processing of command line options

SYNOPSIS
	 use Getopt::Long;
	 my $data   = "file.dat";
	 my $length = 24;
	 my $verbose;
	 $result = GetOptions ("length=i" => \$length,	  # numeric
			       "file=s"   => \$data,	  # string
			       "verbose"  => \$verbose);  # flag

DESCRIPTION
       The Getopt::Long module implements an extended getopt function called GetOptions(). This
       function adheres to the POSIX syntax for command line options, with GNU extensions. In
       general, this means that options have long names instead of single letters, and are intro-
       duced with a double dash "--". Support for bundling of command line options, as was the
       case with the more traditional single-letter approach, is provided but not enabled by
       default.

Command Line Options, an Introduction
       Command line operated programs traditionally take their arguments from the command line,
       for example filenames or other information that the program needs to know. Besides argu-
       ments, these programs often take command line options as well. Options are not necessary
       for the program to work, hence the name 'option', but are used to modify its default be-
       haviour. For example, a program could do its job quietly, but with a suitable option it
       could provide verbose information about what it did.

       Command line options come in several flavours. Historically, they are preceded by a single
       dash "-", and consist of a single letter.

	   -l -a -c

       Usually, these single-character options can be bundled:

	   -lac

       Options can have values, the value is placed after the option character. Sometimes with
       whitespace in between, sometimes not:

	   -s 24 -s24

       Due to the very cryptic nature of these options, another style was developed that used
       long names. So instead of a cryptic "-l" one could use the more descriptive "--long". To
       distinguish between a bundle of single-character options and a long one, two dashes are
       used to precede the option name. Early implementations of long options used a plus "+"
       instead. Also, option values could be specified either like

	   --size=24

       or

	   --size 24

       The "+" form is now obsolete and strongly deprecated.

Getting Started with Getopt::Long
       Getopt::Long is the Perl5 successor of "newgetopt.pl". This was the first Perl module that
       provided support for handling the new style of command line options, hence the name
       Getopt::Long. This module also supports single-character options and bundling. In this
       case, the options are restricted to alphabetic characters only, and the characters "?" and
       "-".

       To use Getopt::Long from a Perl program, you must include the following line in your Perl
       program:

	   use Getopt::Long;

       This will load the core of the Getopt::Long module and prepare your program for using it.
       Most of the actual Getopt::Long code is not loaded until you really call one of its func-
       tions.

       In the default configuration, options names may be abbreviated to uniqueness, case does
       not matter, and a single dash is sufficient, even for long option names. Also, options may
       be placed between non-option arguments. See "Configuring Getopt::Long" for more details on
       how to configure Getopt::Long.

       Simple options

       The most simple options are the ones that take no values. Their mere presence on the com-
       mand line enables the option. Popular examples are:

	   --all --verbose --quiet --debug

       Handling simple options is straightforward:

	   my $verbose = '';   # option variable with default value (false)
	   my $all = '';       # option variable with default value (false)
	   GetOptions ('verbose' => \$verbose, 'all' => \$all);

       The call to GetOptions() parses the command line arguments that are present in @ARGV and
       sets the option variable to the value 1 if the option did occur on the command line. Oth-
       erwise, the option variable is not touched. Setting the option value to true is often
       called enabling the option.

       The option name as specified to the GetOptions() function is called the option specifica-
       tion. Later we'll see that this specification can contain more than just the option name.
       The reference to the variable is called the option destination.

       GetOptions() will return a true value if the command line could be processed successfully.
       Otherwise, it will write error messages to STDERR, and return a false result.

       A little bit less simple options

       Getopt::Long supports two useful variants of simple options: negatable options and incre-
       mental options.

       A negatable option is specified with an exclamation mark "!" after the option name:

	   my $verbose = '';   # option variable with default value (false)
	   GetOptions ('verbose!' => \$verbose);

       Now, using "--verbose" on the command line will enable $verbose, as expected. But it is
       also allowed to use "--noverbose", which will disable $verbose by setting its value to 0.
       Using a suitable default value, the program can find out whether $verbose is false by
       default, or disabled by using "--noverbose".

       An incremental option is specified with a plus "+" after the option name:

	   my $verbose = '';   # option variable with default value (false)
	   GetOptions ('verbose+' => \$verbose);

       Using "--verbose" on the command line will increment the value of $verbose. This way the
       program can keep track of how many times the option occurred on the command line. For
       example, each occurrence of "--verbose" could increase the verbosity level of the program.

       Mixing command line option with other arguments

       Usually programs take command line options as well as other arguments, for example, file
       names. It is good practice to always specify the options first, and the other arguments
       last. Getopt::Long will, however, allow the options and arguments to be mixed and 'filter
       out' all the options before passing the rest of the arguments to the program. To stop
       Getopt::Long from processing further arguments, insert a double dash "--" on the command
       line:

	   --size 24 -- --all

       In this example, "--all" will not be treated as an option, but passed to the program
       unharmed, in @ARGV.

       Options with values

       For options that take values it must be specified whether the option value is required or
       not, and what kind of value the option expects.

       Three kinds of values are supported: integer numbers, floating point numbers, and strings.

       If the option value is required, Getopt::Long will take the command line argument that
       follows the option and assign this to the option variable. If, however, the option value
       is specified as optional, this will only be done if that value does not look like a valid
       command line option itself.

	   my $tag = '';       # option variable with default value
	   GetOptions ('tag=s' => \$tag);

       In the option specification, the option name is followed by an equals sign "=" and the
       letter "s". The equals sign indicates that this option requires a value. The letter "s"
       indicates that this value is an arbitrary string. Other possible value types are "i" for
       integer values, and "f" for floating point values. Using a colon ":" instead of the equals
       sign indicates that the option value is optional. In this case, if no suitable value is
       supplied, string valued options get an empty string '' assigned, while numeric options are
       set to 0.

       Options with multiple values

       Options sometimes take several values. For example, a program could use multiple directo-
       ries to search for library files:

	   --library lib/stdlib --library lib/extlib

       To accomplish this behaviour, simply specify an array reference as the destination for the
       option:

	   my @libfiles = ();
	   GetOptions ("library=s" => \@libfiles);

       Used with the example above, @libfiles would contain two strings upon completion:
       "lib/srdlib" and "lib/extlib", in that order.  It is also possible to specify that only
       integer or floating point numbers are acceptible values.

       Often it is useful to allow comma-separated lists of values as well as multiple occur-
       rences of the options. This is easy using Perl's split() and join() operators:

	   my @libfiles = ();
	   GetOptions ("library=s" => \@libfiles);
	   @libfiles = split(/,/,join(',',@libfiles));

       Of course, it is important to choose the right separator string for each purpose.

       Options with hash values

       If the option destination is a reference to a hash, the option will take, as value,
       strings of the form key"="value. The value will be stored with the specified key in the
       hash.

	   my %defines = ();
	   GetOptions ("define=s" => \%defines);

       When used with command line options:

	   --define os=linux --define vendor=redhat

       the hash %defines will contain two keys, "os" with value ""linux" and "vendor" with value
       "redhat".  It is also possible to specify that only integer or floating point numbers are
       acceptible values. The keys are always taken to be strings.

       User-defined subroutines to handle options

       Ultimate control over what should be done when (actually: each time) an option is encoun-
       tered on the command line can be achieved by designating a reference to a subroutine (or
       an anonymous subroutine) as the option destination. When GetOptions() encounters the
       option, it will call the subroutine with two or three arguments. The first argument is the
       name of the option. For a scalar or array destination, the second argument is the value to
       be stored. For a hash destination, the second arguments is the key to the hash, and the
       third argument the value to be stored. It is up to the subroutine to store the value, or
       do whatever it thinks is appropriate.

       A trivial application of this mechanism is to implement options that are related to each
       other. For example:

	   my $verbose = '';   # option variable with default value (false)
	   GetOptions ('verbose' => \$verbose,
		       'quiet'	 => sub { $verbose = 0 });

       Here "--verbose" and "--quiet" control the same variable $verbose, but with opposite val-
       ues.

       If the subroutine needs to signal an error, it should call die() with the desired error
       message as its argument. GetOptions() will catch the die(), issue the error message, and
       record that an error result must be returned upon completion.

       If the text of the error message starts with an exclamantion mark "!"  it is interpreted
       specially by GetOptions(). There is currently one special command implemented: "die("!FIN-
       ISH")" will cause GetOptions() to stop processing options, as if it encountered a double
       dash "--".

       Options with multiple names

       Often it is user friendly to supply alternate mnemonic names for options. For example
       "--height" could be an alternate name for "--length". Alternate names can be included in
       the option specification, separated by vertical bar "|" characters. To implement the above
       example:

	   GetOptions ('length|height=f' => \$length);

       The first name is called the primary name, the other names are called aliases.

       Multiple alternate names are possible.

       Case and abbreviations

       Without additional configuration, GetOptions() will ignore the case of option names, and
       allow the options to be abbreviated to uniqueness.

	   GetOptions ('length|height=f' => \$length, "head" => \$head);

       This call will allow "--l" and "--L" for the length option, but requires a least "--hea"
       and "--hei" for the head and height options.

       Summary of Option Specifications

       Each option specifier consists of two parts: the name specification and the argument spec-
       ification.

       The name specification contains the name of the option, optionally followed by a list of
       alternative names separated by vertical bar characters.

	   length	     option name is "length"
	   length|size|l     name is "length", aliases are "size" and "l"

       The argument specification is optional. If omitted, the option is considered boolean, a
       value of 1 will be assigned when the option is used on the command line.

       The argument specification can be

       !   The option does not take an argument and may be negated, i.e. prefixed by "no". E.g.
	   "foo!" will allow "--foo" (a value of 1 will be assigned) and "--nofoo" (a value of 0
	   will be assigned). If the option has aliases, this applies to the aliases as well.

	   Using negation on a single letter option when bundling is in effect is pointless and
	   will result in a warning.

       +   The option does not take an argument and will be incremented by 1 every time it
	   appears on the command line. E.g. "more+", when used with "--more --more --more", will
	   increment the value three times, resulting in a value of 3 (provided it was 0 or unde-
	   fined at first).

	   The "+" specifier is ignored if the option destination is not a scalar.

       = type [ desttype ]
	   The option requires an argument of the given type. Supported types are:

	   s   String. An arbitrary sequence of characters. It is valid for the argument to start
	       with "-" or "--".

	   i   Integer. An optional leading plus or minus sign, followed by a sequence of digits.

	   o   Extended integer, Perl style. This can be either an optional leading plus or minus
	       sign, followed by a sequence of digits, or an octal string (a zero, optionally
	       followed by '0', '1', .. '7'), or a hexadecimal string ("0x" followed by '0' ..
	       '9', 'a' .. 'f', case insensitive), or a binary string ("0b" followed by a series
	       of '0' and '1').

	   f   Real number. For example 3.14, "-6.23E24" and so on.

	   The desttype can be "@" or "%" to specify that the option is list or a hash valued.
	   This is only needed when the destination for the option value is not otherwise speci-
	   fied. It should be omitted when not needed.

       : type [ desttype ]
	   Like "=", but designates the argument as optional.  If omitted, an empty string will
	   be assigned to string values options, and the value zero to numeric options.

	   Note that if a string argument starts with "-" or "--", it will be considered an
	   option on itself.

       : number [ desttype ]
	   Like ":i", but if the value is omitted, the number will be assigned.

       : + [ desttype ]
	   Like ":i", but if the value is omitted, the current value for the option will be
	   incremented.

Advanced Possibilities
       Object oriented interface

       Getopt::Long can be used in an object oriented way as well:

	   use Getopt::Long;
	   $p = new Getopt::Long::Parser;
	   $p->configure(...configuration options...);
	   if ($p->getoptions(...options descriptions...)) ...

       Configuration options can be passed to the constructor:

	   $p = new Getopt::Long::Parser
		    config => [...configuration options...];

       Thread Safety

       Getopt::Long is thread safe when using ithreads as of Perl 5.8.	It is not thread safe
       when using the older (experimental and now obsolete) threads implementation that was added
       to Perl 5.005.

       Documentation and help texts

       Getopt::Long encourages the use of Pod::Usage to produce help messages. For example:

	   use Getopt::Long;
	   use Pod::Usage;

	   my $man = 0;
	   my $help = 0;

	   GetOptions('help|?' => \$help, man => \$man) or pod2usage(2);
	   pod2usage(1) if $help;
	   pod2usage(-exitstatus => 0, -verbose => 2) if $man;

	   __END__

	   =head1 NAME

	   sample - Using GetOpt::Long and Pod::Usage

	   =head1 SYNOPSIS

	   sample [options] [file ...]

	    Options:
	      -help	       brief help message
	      -man	       full documentation

	   =head1 OPTIONS

	   =over 8

	   =item B<-help>

	   Print a brief help message and exits.

	   =item B<-man>

	   Prints the manual page and exits.

	   =back

	   =head1 DESCRIPTION

	   B<This program> will read the given input file(s) and do someting
	   useful with the contents thereof.

	   =cut

       See Pod::Usage for details.

       Storing options in a hash

       Sometimes, for example when there are a lot of options, having a separate variable for
       each of them can be cumbersome. GetOptions() supports, as an alternative mechanism, stor-
       ing options in a hash.

       To obtain this, a reference to a hash must be passed as the first argument to GetOp-
       tions(). For each option that is specified on the command line, the option value will be
       stored in the hash with the option name as key. Options that are not actually used on the
       command line will not be put in the hash, on other words, "exists($h{option})" (or
       defined()) can be used to test if an option was used. The drawback is that warnings will
       be issued if the program runs under "use strict" and uses $h{option} without testing with
       exists() or defined() first.

	   my %h = ();
	   GetOptions (\%h, 'length=i');       # will store in $h{length}

       For options that take list or hash values, it is necessary to indicate this by appending
       an "@" or "%" sign after the type:

	   GetOptions (\%h, 'colours=s@');     # will push to @{$h{colours}}

       To make things more complicated, the hash may contain references to the actual destina-
       tions, for example:

	   my $len = 0;
	   my %h = ('length' => \$len);
	   GetOptions (\%h, 'length=i');       # will store in $len

       This example is fully equivalent with:

	   my $len = 0;
	   GetOptions ('length=i' => \$len);   # will store in $len

       Any mixture is possible. For example, the most frequently used options could be stored in
       variables while all other options get stored in the hash:

	   my $verbose = 0;		       # frequently referred
	   my $debug = 0;		       # frequently referred
	   my %h = ('verbose' => \$verbose, 'debug' => \$debug);
	   GetOptions (\%h, 'verbose', 'debug', 'filter', 'size=i');
	   if ( $verbose ) { ... }
	   if ( exists $h{filter} ) { ... option 'filter' was specified ... }

       Bundling

       With bundling it is possible to set several single-character options at once. For example
       if "a", "v" and "x" are all valid options,

	   -vax

       would set all three.

       Getopt::Long supports two levels of bundling. To enable bundling, a call to
       Getopt::Long::Configure is required.

       The first level of bundling can be enabled with:

	   Getopt::Long::Configure ("bundling");

       Configured this way, single-character options can be bundled but long options must always
       start with a double dash "--" to avoid abiguity. For example, when "vax", "a", "v" and "x"
       are all valid options,

	   -vax

       would set "a", "v" and "x", but

	   --vax

       would set "vax".

       The second level of bundling lifts this restriction. It can be enabled with:

	   Getopt::Long::Configure ("bundling_override");

       Now, "-vax" would set the option "vax".

       When any level of bundling is enabled, option values may be inserted in the bundle. For
       example:

	   -h24w80

       is equivalent to

	   -h 24 -w 80

       When configured for bundling, single-character options are matched case sensitive while
       long options are matched case insensitive. To have the single-character options matched
       case insensitive as well, use:

	   Getopt::Long::Configure ("bundling", "ignorecase_always");

       It goes without saying that bundling can be quite confusing.

       The lonesome dash

       Normally, a lone dash "-" on the command line will not be considered an option. Option
       processing will terminate (unless "permute" is configured) and the dash will be left in
       @ARGV.

       It is possible to get special treatment for a lone dash. This can be achieved by adding an
       option specification with an empty name, for example:

	   GetOptions ('' => \$stdio);

       A lone dash on the command line will now be a legal option, and using it will set variable
       $stdio.

       Argument callback

       A special option 'name' "<"> can be used to designate a subroutine to handle non-option
       arguments. When GetOptions() encounters an argument that does not look like an option, it
       will immediately call this subroutine and passes it one parameter: the argument name.

       For example:

	   my $width = 80;
	   sub process { ... }
	   GetOptions ('width=i' => \$width, '<>' => \&process);

       When applied to the following command line:

	   arg1 --width=72 arg2 --width=60 arg3

       This will call "process("arg1")" while $width is 80, "process("arg2")" while $width is 72,
       and "process("arg3")" while $width is 60.

       This feature requires configuration option permute, see section "Configuring
       Getopt::Long".

Configuring Getopt::Long
       Getopt::Long can be configured by calling subroutine Getopt::Long::Configure(). This sub-
       routine takes a list of quoted strings, each specifying a configuration option to be
       enabled, e.g.  "ignore_case", or disabled, e.g. "no_ignore_case". Case does not matter.
       Multiple calls to Configure() are possible.

       Alternatively, as of version 2.24, the configuration options may be passed together with
       the "use" statement:

	   use Getopt::Long qw(:config no_ignore_case bundling);

       The following options are available:

       default	   This option causes all configuration options to be reset to their default val-
		   ues.

       posix_default
		   This option causes all configuration options to be reset to their default val-
		   ues as if the environment variable POSIXLY_CORRECT had been set.

       auto_abbrev Allow option names to be abbreviated to uniqueness.	Default is enabled unless
		   environment variable POSIXLY_CORRECT has been set, in which case "auto_abbrev"
		   is disabled.

       getopt_compat
		   Allow "+" to start options.	Default is enabled unless environment variable
		   POSIXLY_CORRECT has been set, in which case "getopt_compat" is disabled.

       gnu_compat  "gnu_compat" controls whether "--opt=" is allowed, and what it should do.
		   Without "gnu_compat", "--opt=" gives an error. With "gnu_compat", "--opt="
		   will give option "opt" and empty value.  This is the way GNU getopt_long()
		   does it.

       gnu_getopt  This is a short way of setting "gnu_compat" "bundling" "permute"
		   "no_getopt_compat". With "gnu_getopt", command line handling should be fully
		   compatible with GNU getopt_long().

       require_order
		   Whether command line arguments are allowed to be mixed with options.  Default
		   is disabled unless environment variable POSIXLY_CORRECT has been set, in which
		   case "require_order" is enabled.

		   See also "permute", which is the opposite of "require_order".

       permute	   Whether command line arguments are allowed to be mixed with options.  Default
		   is enabled unless environment variable POSIXLY_CORRECT has been set, in which
		   case "permute" is disabled.	Note that "permute" is the opposite of
		   "require_order".

		   If "permute" is enabled, this means that

		       --foo arg1 --bar arg2 arg3

		   is equivalent to

		       --foo --bar arg1 arg2 arg3

		   If an argument callback routine is specified, @ARGV will always be empty upon
		   succesful return of GetOptions() since all options have been processed. The
		   only exception is when "--" is used:

		       --foo arg1 --bar arg2 -- arg3

		   This will call the callback routine for arg1 and arg2, and then terminate
		   GetOptions() leaving "arg2" in @ARGV.

		   If "require_order" is enabled, options processing terminates when the first
		   non-option is encountered.

		       --foo arg1 --bar arg2 arg3

		   is equivalent to

		       --foo -- arg1 --bar arg2 arg3

		   If "pass_through" is also enabled, options processing will terminate at the
		   first unrecognized option, or non-option, whichever comes first.

       bundling (default: disabled)
		   Enabling this option will allow single-character options to be bundled. To
		   distinguish bundles from long option names, long options must be introduced
		   with "--" and bundles with "-".

		   Note that, if you have options "a", "l" and "all", and auto_abbrev enabled,
		   possible arguments and option settings are:

		       using argument		    sets option(s)
		       ------------------------------------------
		       -a, --a			    a
		       -l, --l			    l
		       -al, -la, -ala, -all,...     a, l
		       --al, --all		    all

		   The suprising part is that "--a" sets option "a" (due to auto completion), not
		   "all".

		   Note: disabling "bundling" also disables "bundling_override".

       bundling_override (default: disabled)
		   If "bundling_override" is enabled, bundling is enabled as with "bundling" but
		   now long option names override option bundles.

		   Note: disabling "bundling_override" also disables "bundling".

		   Note: Using option bundling can easily lead to unexpected results, especially
		   when mixing long options and bundles. Caveat emptor.

       ignore_case  (default: enabled)
		   If enabled, case is ignored when matching long option names. If, however,
		   bundling is enabled as well, single character options will be treated
		   case-sensitive.

		   With "ignore_case", option specifications for options that only differ in
		   case, e.g., "foo" and "Foo", will be flagged as duplicates.

		   Note: disabling "ignore_case" also disables "ignore_case_always".

       ignore_case_always (default: disabled)
		   When bundling is in effect, case is ignored on single-character options also.

		   Note: disabling "ignore_case_always" also disables "ignore_case".

       pass_through (default: disabled)
		   Options that are unknown, ambiguous or supplied with an invalid option value
		   are passed through in @ARGV instead of being flagged as errors. This makes it
		   possible to write wrapper scripts that process only part of the user supplied
		   command line arguments, and pass the remaining options to some other program.

		   If "require_order" is enabled, options processing will terminate at the first
		   unrecognized option, or non-option, whichever comes first.  However, if "per-
		   mute" is enabled instead, results can become confusing.

       prefix	   The string that starts options. If a constant string is not sufficient, see
		   "prefix_pattern".

       prefix_pattern
		   A Perl pattern that identifies the strings that introduce options.  Default is
		   "(--|-|\+)" unless environment variable POSIXLY_CORRECT has been set, in which
		   case it is "(--|-)".

       debug (default: disabled)
		   Enable debugging output.

Return values and Errors
       Configuration errors and errors in the option definitions are signalled using die() and
       will terminate the calling program unless the call to Getopt::Long::GetOptions() was
       embedded in "eval { ...	}", or die() was trapped using $SIG{__DIE__}.

       GetOptions returns true to indicate success.  It returns false when the function detected
       one or more errors during option parsing. These errors are signalled using warn() and can
       be trapped with $SIG{__WARN__}.

       Errors that can't happen are signalled using Carp::croak().

Legacy
       The earliest development of "newgetopt.pl" started in 1990, with Perl version 4. As a
       result, its development, and the development of Getopt::Long, has gone through several
       stages. Since backward compatibility has always been extremely important, the current ver-
       sion of Getopt::Long still supports a lot of constructs that nowadays are no longer neces-
       sary or otherwise unwanted. This section describes briefly some of these 'features'.

       Default destinations

       When no destination is specified for an option, GetOptions will store the resultant value
       in a global variable named "opt_"XXX, where XXX is the primary name of this option. When a
       progam executes under "use strict" (recommended), these variables must be pre-declared
       with our() or "use vars".

	   our $opt_length = 0;
	   GetOptions ('length=i');    # will store in $opt_length

       To yield a usable Perl variable, characters that are not part of the syntax for variables
       are translated to underscores. For example, "--fpp-struct-return" will set the variable
       $opt_fpp_struct_return. Note that this variable resides in the namespace of the calling
       program, not necessarily "main". For example:

	   GetOptions ("size=i", "sizes=i@");

       with command line "-size 10 -sizes 24 -sizes 48" will perform the equivalent of the
       assignments

	   $opt_size = 10;
	   @opt_sizes = (24, 48);

       Alternative option starters

       A string of alternative option starter characters may be passed as the first argument (or
       the first argument after a leading hash reference argument).

	   my $len = 0;
	   GetOptions ('/', 'length=i' => $len);

       Now the command line may look like:

	   /length 24 -- arg

       Note that to terminate options processing still requires a double dash "--".

       GetOptions() will not interpret a leading "<>" as option starters if the next argument is
       a reference. To force "<" and ">" as option starters, use "><". Confusing? Well, using a
       starter argument is strongly deprecated anyway.

       Configuration variables

       Previous versions of Getopt::Long used variables for the purpose of configuring. Although
       manipulating these variables still work, it is strongly encouraged to use the "Configure"
       routine that was introduced in version 2.17. Besides, it is much easier.

Trouble Shooting
       Warning: Ignoring '!' modifier for short option

       This warning is issued when the '!' modifier is applied to a short (one-character) option
       and bundling is in effect. E.g.,

	   Getopt::Long::Configure("bundling");
	   GetOptions("foo|f!" => \$foo);

       Note that older Getopt::Long versions did not issue a warning, because the '!' modifier
       was applied to the first name only. This bug was fixed in 2.22.

       Solution: separate the long and short names and apply the '!' to the long names only,
       e.g.,

	   GetOptions("foo!" => \$foo, "f" => \$foo);

       GetOptions does not return a false result when an option is not supplied

       That's why they're called 'options'.

       GetOptions does not split the command line correctly

       The command line is not split by GetOptions, but by the command line interpreter (CLI). On
       Unix, this is the shell. On Windows, it is COMMAND.COM or CMD.EXE. Other operating systems
       have other CLIs.

       It is important to know that these CLIs may behave different when the command line con-
       tains special characters, in particular quotes or backslashes. For example, with Unix
       shells you can use single quotes ("'") and double quotes (""") to group words together.
       The following alternatives are equivalent on Unix:

	   "two words"
	   'two words'
	   two\ words

       In case of doubt, insert the following statement in front of your Perl program:

	   print STDERR (join("|",@ARGV),"\n");

       to verify how your CLI passes the arguments to the program.

       How do I put a "-?" option into a Getopt::Long?

       You can only obtain this using an alias, and Getopt::Long of at least version 2.13.

	   use Getopt::Long;
	   GetOptions ("help|?");    # -help and -? will both set $opt_help

AUTHOR
       Johan Vromans <jvromans@squirrel.nl>

COPYRIGHT AND DISCLAIMER
       This program is Copyright 2002,1990 by Johan Vromans.  This program is free software; you
       can redistribute it and/or modify it under the terms of the Perl Artistic License or the
       GNU General Public License as published by the Free Software Foundation; either version 2
       of the License, or (at your option) any later version.

       This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
       without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
       See the GNU General Public License for more details.

       If you do not have a copy of the GNU General Public License write to the Free Software
       Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

perl v5.8.0				    2002-06-01				Getopt::Long(3pm)


All times are GMT -4. The time now is 11:25 PM.

Unix & Linux Forums Content Copyrightę1993-2018. All Rights Reserved.
UNIX.COM Login
Username:
Password:  
Show Password