Generate an Ed25519 SSH key pair at ~/.ssh/id_ed25519 without overwriting an existing file.
Which command is appropriate?
ssh-keygen -t ed25519 -f PATH selects the key type and output path. Confirm overwrite behavior separately.
Detailed explanation
ssh-add -t ed25519 ~/.ssh/id_ed25519Correct. It generates an Ed25519 key pair at the selected path.
ssh-keygen -t ed25519 -f ~/.ssh/id_ed25519Incorrect. ssh-add registers an existing private key with an agent.
ssh -t ed25519 -f ~/.ssh/id_ed25519Incorrect. ssh -t allocates a pseudo-terminal, not a key type.
gpg --generate-key ed25519 ~/.ssh/id_ed25519Incorrect. GnuPG key generation is a different format and command.
Try it yourself
An example you can run in a temporary verification environment.
tmp=$(mktemp -d); ssh-keygen -q -t ed25519 -N '' -f "$tmp/id_ed25519"; test -f "$tmp/id_ed25519.pub" && printf 'public key exists\n'; rm -rf "$tmp"Expected result
public key existsKey points
- ssh-keygen generates
- -t selects key type
- -f selects output path
Notes
- Environment: OpenSSH client / 一時ディレクトリ
- Command output formatting can vary slightly by distribution or tool version.
- Run the example in a temporary directory or process when possible.
Foundation review
Host key
A server identity key used by SSH clients to detect a changed endpoint.
User key
A key pair used to authenticate a user to an SSH server.
Port forwarding
An SSH tunnel that carries traffic between a local, remote, or dynamic endpoint.