#!/usr/bin/perl -w
$filelist = "/home/exp/acctlist.txt";
open(FILEDUPS, $filelist) || die ("Cannot open $filelist");
open($output, '>', '/home/exp/output.txt') || die ("Cannot open
file");

while ($line = <FILEDUPS>) {
chomp $line;
($filename, undef, undef, undef, undef) = split /\t/, $line;  
}

$uniquefiles{$filename} = 1;
foreach $k (keys %uniquefiles) {
print $output "$k\n";
}