This code demonstrates some basics about opening and closing a file, using a regular expression to search for specific lines, and using strictures (warnings/strict) to enforce good coding practices.

#!/usr/bin/env perl
 
use warnings;
use strict;
 
open my $fh, '<', 'foo.txt' or die "Can not open file: foo.txt: $!\n";
while (<$fh>) {
    if (/^\w{3};\w/) {
        print; # or do whatever you need to do...
    }
}
close $fh or die "Can not close file: foo.txt: $!\n";
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Here is the output, assuming "foo.txt" is your start file:

TEC;UTF;TDE;450
TEC;URT;TDE;687
TEC;UGC;TDE;687
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