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

my %id2seq = ();
my $id = '';

open File,"human_hg19_circRNAs_putative_spliced_sequence.fa",or die $!;

    while(<File>){
        chomp;
        if($_ =~ /^>(.+)/){
            $id = $1;
        }else{
            $id2seq{$id} .= $_;
        }
    }

 

    foreach $id (keys %id2seq){
        if (-f $id){
            print $id." Already exists, about to override it","\n"
        }
        open  my $out_fh, '>>', "$id.fa" or die $!; 
        print $out_fh (">".$id."\n",$id2seq{$id}, "\n");
        close $out_fh;
    }


close File;