use IPC::Cmd qw{run};

$ssh_cp_id = '';
$ssh_cp_id_result = run(
	'command'=>"ssh-copy-id -i $path_pk $user\@$server 2>/dev/null",
	'buffer'=>\$ssh_cp_id
);
if($ssh_cp_id_result){
	#print has no effect, as the password prompt got already displayed without being captured to the $ssh_cp_id:
	print $ssh_cp_id;
}