Use a package (our) variable instead of a lexical (my) variable:

package main;
use Getopt::Std;
our %opts;
getopts('fs', \%opts);

package Foo;
if ($main::opts{s}) { #do stuff }

package Bar;
if ($main::opts{s}) { #do stuff }
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You can even create an alias:

package main;
use Getopt::Std;
our %opts;
getopts('fs', \%opts);

package Foo;
our %opts;
*opts = \%main::opts;
if ($opts{s}) { #do stuff }

package Bar;
our %opts;
*opts = \%main::opts;
if ($opts{s}) { #do stuff }
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I hate referencing main explicitely, so I prefer importing the symbol from a module that will handle the options:

# Optionally in seperate file Opts.pm
package Opts;  
use Getopt::Std;
our %opts;
our @EXPORT = qw( %opts );
our @ISA = 'Exporter';
require Exporter;
getopts('fs', \%opts);
1;

package Foo;
use Opts qw( %opts );
if ($opts{s}) { #do stuff }

package Bar;
use Opts qw( %opts );  # Safe to do multiple times.
if ($opts{s}) { #do stuff }
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