NAME¶
getopt, getopts - 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 $opt_y will be set to an
undefined value. Unspecified switches are silently accepted.
Use of
"getopts()" is not recommended.
Note that, if your code is running under the recommended "use strict
vars" pragma, you will need to declare these package variables with
"our":
our($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.