getseqfromNCBIbygi

#! /usr/bin/perl -w
#get sequences from NCBI according to gi
use strict;
use Bio::Perl;
use Bio::SeqIO;
use Bio::Seq;

open(GIIN,"$ARGV[0]") or die "Cannot open file";
open(GIED,"> $ARGV[1]") or die "cannot create file";

my @allgi=<GIIN>; #read all of gies
my $seqout = new Bio::SeqIO(-file =>'>> nameofafile', -format => "genbank");

foreach my $allgi(@allgi){
    my $seq = get_sequence('genbank', $allgi);
    if($seq){
        $seqout->write_seq($seq);    
        my $gied = $allgi;
        print GIED "$gied"; #put gies of downloaded sequences into a file
    }
}

close GIIN;
close GIED;