my @ids =<IDLIST>;
chomp @ids;

##</code><code>##

foreach my $id (@ids) {
    foreach my $fasta (@files) {
        open my $fh, '<', $fasta or die "can not open file $fasta: $!";
        while (<$fh>) {
            print if /$id/;
        }
        close $fh;
    }
}