Maybe this code will start you on the right direction

use strict;
my $newdata = '124|20030812|uiy|kjh|87';
my $db = "textfile.txt";
open (DATAFILE, "+<$db") or die $!;
my $key = join("|", (split /\|/, $newdata)[1,4]);
while (<DATAFILE>) {
    chomp;
    if (join("|", (split /\|/)[1,4]) eq $key) {
        close DATAFILE;
        exit;
    }
}
print DATAFILE $newdata,"\n";
close DATAFILE;
[download]

$newdata will be added to the text file if it is not already there. I would probably put this in a sub and do a return instead of an exit. This consumes no extra memory no matter how big textfile.txt gets.

--

flounder