Getopt::Std(3p) Perl Programmers Reference Guide Getopt::Std(3p)NAME
Getopt::Std, getopt, getopts - Process single-character
switches with switch clustering
SYNOPSIS
use Getopt::Std;
getopt('oDI'); # -o, -D & -I take arg. Sets $opt_* as a side effect.
getopt('oDI', \%opts); # -o, -D & -I take arg. Values in %opts
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
DESCRIPTION
The getopt() function processes single-character switches
with switch clustering. Pass one argument which is a string
containing all switches that take an argument. For each
switch found, sets $opt_x (where x is the switch name) to
the value of the argument if an argument is expected, or 1
otherwise. Switches which take an argument don't care
whether there is a space between the switch and the argu-
ment.
The getopts() function is similar, but you should pass to it
the list of all switches to be recognized. If unspecified
switches are found on the command-line, the user will be
warned that an unknown option was given.
Note that, if your code is running under the recommended
"use strict 'vars'" pragma, you will need to declare these
package variables with "our":
our($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
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Getopt::Std(3p) Perl Programmers Reference Guide Getopt::Std(3p)
defined, an attempt is made to generate intelligent mes-
sages; 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.
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