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

my $data_file = '/DATA/GenBankFile.gb';
open INFILE, '<', $data_file or die "Could not open '$data_file' $!";

my ( $cds, $gi, $version );
while ( <INFILE> ) {
    last if m!//$!;
    if ( /^VERSION.*\w:(\d+)/ ) {
        $version = $1;
        }
    elsif ( /^\s*\Sdb_xref="GI:(\d+)/ ) {
        $gi = $1;
        }
    elsif ( /^\s*CDS\s*(\S+)/ ) {
        $cds = $1;
        }
    if ( defined $cds && defined $gi && defined $version ) {
        print "$gi\t$version\t$cds\n";
        $gi = $cds = undef;
        }
    }

close INFILE;