----------------main.pl---------------------

require '../somepath/../abc.pl';
require '../somepath/../def.pl';

# Call a sub-routing in abc.pl 

&sub_in_abc();

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

##</code><code>##

----------------main.pl---------------------

require '../somepath/../abc.pl';
require '../somepath/../def.pl';

use Client;

# Call a sub-routing in abc.pl 

&sub_in_abc();

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