Pease edit your title 'passing hash ref to a function'

Where is p2 script located relative to p1 script. Are they are they both in the same folder ? they just use

my $output = `p2.pl`;
Update

If yes, FindBin can locate the path to p1.pl which can be used to run p2.pl.

#!perl
# p1.pl
use strict;
use FindBin;

my $p2 = $FindBin::Bin.'/p2.pl';
my $output = `$p2`;
print $output;
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poj