ssh-copy-id - use locally available keys to authorise logins on a remote machine

Options you will use

-i identity_file

the public key to copy (default: the newest of ~/.ssh/id*.pub)

-f

force: do not first try to log in with the key to check whether it is already installed

-p port

connect to this port

-o ssh_option

passed to ssh

Examples

$ ssh-copy-id web-1

log in once with the password, append ~/.ssh/id_ed25519.pub to ~/.ssh/authorized_keys there

$ ssh-copy-id -i ~/.ssh/deploy.pub deploy@db-1

another key, another user

Gotchas

• It needs one working login (usually the password). On cloud images PasswordAuthentication is off: then the key goes in through cloud-init / the provider, not ssh-copy-id.
• It creates ~/.ssh (700) and authorized_keys (600) on the remote side; a group-writable ~/.ssh makes sshd ignore the key (StrictModes).