open (my $fhConditions, "<1.txt"); my $l=6; open (my $read, "<2.txt"); my @e = <$read>; my $d = join('', @e ); $d =~ s/\s+//g; while (<$fhConditions>) { push (my @line, $_); my $count++; } for (my $i = 0; $i <$count; $i++) { my @pos = $line[$i] =~ /chr[0-9]\s+(.+?)\s/g; if($pos[0] =~/[0-9]/) { my $match = substr($d,$pos[0],$l); print "$line[$i]" if $match =~m/AAGCTT/; } if($pos[1] =~/[0-9]/) { my $a = $pos[0]-$l; my $match = substr($d,$a,$l); print "$line[$i]" if $match =~m/AAGCTT/; } }