in reply to "do" command versus "source" in bash

Of course. Just define your variable in the invoking program as well: 

#!/usr/bin/perl
use warnings;
use strict;
our $path1;
do './paths.pl'; # you have to use ./, since '.' is no longer in @INC

print $path1."\n";

[download]
perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'

In Section Seekers of Perl Wisdom