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

open(FH,"input.txt")or die "can not open input file\n";
while (my $line=<FH>) {
    my (undef, undef, undef, $four, undef) = split("\t",$line);
    if ($four=~m/S(\d+)GM/){
        my $F = get_file_handle($1);
        print $F $line;
    }
}