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getopt - Process single-character switches with switch clustering

getopts - Process single-character switches with switch clustering


    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


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 argument.

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.