Thanks for the reply.
but the code u gave prints the contents as below.

VAR1 = {
          '' => {
                  'last_used' => '2007/12/20',
                  'user_name' => 'xyz',
                  'host_name' => 'nett1'
                }
        };

But I need to print the contents as the below code does.
 foreach (sort keys %hoh){
 print "$_ ";
 my $tmp_hash = $hoh{$_};
 foreach (sort keys %$tmp_hash){
 print $$tmp_hash{$_};
 print " ";
 }
 print "\n";
}