How to copy your SSH key to a headless machine¶

You have a long public key on your laptop and need it in ~/.ssh/authorized_keys on a new box — but you're at a console where you can't paste, or you want it scripted.

Easiest: ssh-copy-id (when password login still works)¶

ssh-copy-id user@host

Prompts for the password once, appends your key, and fixes permissions. Done.

Console-only: serve the key over HTTP and pull it¶

When you're at the machine's console (no paste) but it's on the LAN, serve the key from your laptop and curl it in — no typing the key:

# on the laptop, in the folder holding the .pub key
python3 -m http.server 8000

# on the target machine
install -d -m700 ~/.ssh
curl -fsSL http://<laptop-ip>:8000/id_ed25519.pub >> ~/.ssh/authorized_keys
chmod 600 ~/.ssh/authorized_keys

Stop the http.server afterwards.

Manual, if you must type it¶

The key must be one single line:

install -d -m700 ~/.ssh
printf '%s\n' 'ssh-ed25519 AAAA... you@laptop' >> ~/.ssh/authorized_keys
chmod 600 ~/.ssh/authorized_keys