What you want is a perl module file. The basics are documented in the documentation of perlmod under "Modules" .

Here is a trivial example: This script uses say_hello:

#! perl -w
use strict;
use warnings;

use mystuff;

mystuff::say_hello "world";
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... and say_hello is defined in this script, which should be saved as "mystuff.pm" in the same directory.

#! perl -w
use warnings;
use strict;

package mystuff;

sub say_hello {
    print "hello " . shift() . "\n";
}

1
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If you run the first script above with

$ perl -w example.pl
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it will print

hello world
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