../Getopt/Std.pm
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.
    getopts('oif:');  # -o & -i are boolean flags, -f takes an argument
                      # Sets opt_* as a side effect.
The getopt() functions 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, or 1 if no argument.  Switches
which take an argument don't care whether there is a space between the
switch and the argument.