#!/usr/local/bin/perl use warnings; open ( my $input_fh, "<", $genome ); open ( my $output_fh, ">", $output_file ); foreach my $line ( <$input_fh> ) { unless ( $line =~ m/\A\s*\Z/ ) { $line =~ s/(GL\d{6})\d+/$1/; print $output_fh $line; } } close ( $input_fh ); close ( $output_fh );