#!/usr/bin/perl

#Always
use strict;
use warnings;

#Use lexical variables instead of bareword filehandles
open my $in, "<", "input_file"
    or die "Couldn't read input_file: $!\n";

my @results;

while (<$in>) {
    chomp;
    push @results, $_ unless /^\s*$/;
}

#Close filehandle's when you're done with them.
close $in;

open my $out2, ">>", "output_file" 
    or die "Couldn't open output_file: $!\n";

for (@results) {
    print $out2 "$_\n" if s/.*\///;
}

close $out2;