Shell Programming and Scripting

use strict;
my ($n,$ind,%hash,%hash2)=(1,5);
open FH,"<a.txt";
while(<FH>){
	my @tmp=split("/",$_);
	if (not exists $hash2{$tmp[0]}){
		$hash2{$tmp[0]}->{SEQ}=$n;
		$n++;
	}
	$hash{$tmp[0]}->{$tmp[1]}.=" " x (2*$ind).$tmp[2];
}
close FH;
for my $out_key (sort {$hash2{$a} <=> $hash2{$b} } keys %hash){
	print $out_key,"\n";
	my %h = %{$hash{$out_key}};
	for my $in_key (sort keys %h){
		print " " x $ind;
		print $in_key,"\n";
		print $h{$in_key};
	}
}