If you want to setup SSH keys to allow logging in without a password, you can do so with a single command.
The first thing you’ll need to do is make sure you’ve run the keygen command to generate the keys:
ssh-keygen -t rsa
Then use this command to push the key to the remote server, modifying it to match your server name.
cat ~/.ssh/id_rsa.pub | ssh user@hostname 'cat >> .ssh/authorized_keys'