#!/usr/bin/env perl
use warnings;
use strict;

my $filename = shift;
open my $test_fh, '<', $filename or die "Can not open file $filename: $!\n";
while (<$test_fh>) {
    my @tokens = split;
    for my $token (@tokens) {
        if ($token =~ /\wp\w/i) { print $token, "\n" }
    }
}
close ($test_fh);