#!/usr/bin/perl 

use strict;

use warnings;

use Bio::SeqIO;

my $seqin = Bio::SeqIO->new(-file     => 'nr',
                                -format => 'fasta');
my $seqout = Bio::SeqIO->new(-file   => ">mini_nr",
                                 -format => 'fasta');

# write each entry in the input file to the output file
my $i = 0;
while ($i < 1000) {
	my $inseq = $seqin->next_seq
        $seqout->write_seq($inseq);
	$i++;
}
    exit;