problems trying to cycle through files and modify them

Hi

I'm writing a script to cycle through the files in a directory and modify if an update file contains certain information. The problems im having (well, the problem im up to) is that i cant seem to extract the first line of the files to update in order to extract a number i need to use to match with the update file. My print debug line is doing nothing. I seem to be able to cycle and open the files fine - its just that i cant seem to be able to do anything with them. Heres the code:

#!/usr/bin/perl
use strict;
my $direc = "/home/jgs/blastportal/";
my $prefix = "taxGI_";

print("Update?: ");
my $in = <STDIN>;
chomp($in);

if($in eq "y"){
    my $update = $direc. "gi_taxid_nucl_diff.dmp";
    open(UPDLIST, $update) || die("Canont open update list.");

    opendir(DIR, $direc);
    my @files = grep(/($prefix)/,readdir(DIR));
    closedir(DIR);
   
foreach my $file(@files){
    my $path = $direc.$file;
    print $path;
    open(TAXFILE, "+>> $path") || die("Cannot open a tax file");
    my $firstline = <TAXFILE>;
    print $firstline;
    my $id = ($firstline =~ /\s+\d$/);
 
    while(<UPDLIST>){
      print TAXFILE if(/\s+($id)/);
    }
    close(TAXFILE);
}
close(UPDLIST);

}

I'm new to perl so any advice would be very useful.

thanks