- gpg2, gpg-agent etc.
- see developers.yubico.com[...]/Importing_keys.html
- Make sure the Yubikey is shown
gpg2 --card-status
- Grep the ID for the subkey for authentication, e.g. ABCDEFFF
set subkeyId (gpg2 --list-secret-keys | grep '\[A\]' | cut -d'/' -f 2 | cut -d' ' -f 1)