I opened the ~/.ssh/known_hosts it does not have anything in it but for me it is still working the same way.
Secondly, is there any other way to add as I dont want to give the password to everyone for running the script?
Comment on Re^2: Perl SCP ERROR(Asking to Continue?)
The easiest way is to, in some way, get ssh called with the StrictHostKeyChecking option set to no (see ssh_config(5)).
Though using that option can have a negative impact on the security of the SSH protocol. I usually disregard its usage unless its implications are really understood.