Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
Getopt::Std(3)	       Perl Programmers	Reference Guide		Getopt::Std(3)

NAME
       Getopt::Std - Process single-character switches with switch clustering

SYNOPSIS
	   use Getopt::Std;

	   getopts('oif:');  # -o & -i are boolean flags, -f takes an argument
			     # Sets $opt_* as a	side effect.
	   getopts('oif:', \%opts);  # options as above. Values	in %opts
	   getopt('oDI');    # -o, -D &	-I take	arg.
			     # Sets $opt_* as a	side effect.
	   getopt('oDI', \%opts);    # -o, -D &	-I take	arg.  Values in	%opts

DESCRIPTION
       The "getopts()" function	processes single-character switches with
       switch clustering.  Pass	one argument which is a	string containing all
       switches	to be recognized.  For each switch found, if an	argument is
       expected	and provided, "getopts()" sets $opt_x (where "x" is the	switch
       name) to	the value of the argument.  If an argument is expected but
       none is provided, $opt_x	is set to an undefined value.  If a switch
       does not	take an	argument, $opt_x is set	to 1.

       Switches	which take an argument don't care whether there	is a space
       between the switch and the argument.  If	unspecified switches are found
       on the command-line, the	user will be warned that an unknown option was
       given.

       The "getopts()" function	returns	true unless an invalid option was
       found.

       The "getopt()" function is similar, but its argument is a string
       containing all switches that take an argument.  If no argument is
       provided	for a switch, say, "y",	the corresponding $opt_y will be set
       to an undefined value.  Unspecified switches are	silently accepted.
       Use of "getopt()" is not	recommended.

       Note that, if your code is running under	the recommended	"use strict
       vars" pragma, you will need to declare these package variables with
       "our":

	   our($opt_x, $opt_y);

       For those of you	who don't like additional global variables being
       created,	"getopt()" and "getopts()" will	also accept a hash reference
       as an optional second argument.	Hash keys will be "x" (where "x" is
       the switch name)	with key values	the value of the argument or 1 if no
       argument	is specified.

       To allow	programs to process arguments that look	like switches, but
       aren't, both functions will stop	processing switches when they see the
       argument	"--".  The "--"	will be	removed	from @ARGV.

"--help" and "--version"
       If "-" is not a recognized switch letter, getopts() supports arguments
       "--help"	and "--version".  If "main::HELP_MESSAGE()" and/or
       "main::VERSION_MESSAGE()" are defined, they are called; the arguments
       are the output file handle, the name of option-processing package, its
       version,	and the	switches string.  If the subroutines are not defined,
       an attempt is made to generate intelligent messages; for	best results,
       define $main::VERSION.

       If embedded documentation (in pod format, see perlpod) is detected in
       the script, "--help" will also show how to access the documentation.

       Note that due to	excessive paranoia, if
       $Getopt::Std::STANDARD_HELP_VERSION isn't true (the default is false),
       then the	messages are printed on	STDERR,	and the	processing continues
       after the messages are printed.	This being the opposite	of the
       standard-conforming behaviour, it is strongly recommended to set
       $Getopt::Std::STANDARD_HELP_VERSION to true.

       One can change the output file handle of	the messages by	setting
       $Getopt::Std::OUTPUT_HELP_VERSION.  One can print the messages of
       "--help"	(without the "Usage:" line) and	"--version" by calling
       functions help_mess() and version_mess()	with the switches string as an
       argument.

perl v5.28.3			  2020-05-14			Getopt::Std(3)

NAME | SYNOPSIS | DESCRIPTION | "--help" and "--version"

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=Getopt::Std&sektion=3&manpath=FreeBSD+13.0-RELEASE+and+Ports>

home | help