# file foo.pm
package foo;
$foo = 1;

---------------------------

# file foo.pl
use strict;
use foo;
print $foo::foo,$/;

---------------------------

[jeffa@trinity perl]$ perl -c foo.pm
foo.pm syntax OK
[jeffa@trinity perl]$ perl -c foo.pl
foo.pl syntax OK
[jeffa@trinity perl]$ ./foo.pl
1