#!/usr/bin/perl -w
use strict;
use warnings;

my %subst;
my $data = 'reference.txt'; 
open my $INFILE, '<', $data or die "cannot read $data: $!";

while(defined my $line = <$INFILE>)
{
   chomp($line);
    my ($id, $description) = split /\t/, $line, 2;
	$subst{$id} = $description;
}
close $INFILE;

my $data2 = 'readthisfile.txt'; 
open my $INFILE2, '<', $data2 or die "cannot read $data2: $!";

while(defined my $line2 = <$INFILE2>)
{
   ## chomp($line2); Dont chomp - leave newline in for printing
    my $changes = 0;
    for my $id (keys %subst){
        if ($line2 =~s/$id/$subst{$id}/g){
		   # This line was changed
		   $changes++;
		}
    }
    print $line2  if $changes; #Prints only changed lines
}
close $INFILE2;