ssh-copy-id
ssh-copy-id [user@]<host>
Risk: Safe
What it does
Hangs your padlock on a server: adds your public key to its authorized_keys.
When to use it
Once per server, while a password login still works.
Example
$ ssh-copy-id you@10.0.0.5One last password, then key logins.
Learn it in: SSH keys · Official docs