Ssh-add

ssh-add adds private key identities to the OpenSSH authentication agent (ssh-agent)

• https://man.openbsd.org/ssh-add
• https://linux.die.net/man/1/ssh-add

ssh-add
(no output)

ssh-add
Could not open a connection to your authentication agent.

Solution:
Execute ssh-agent

ssh-add id_ed25519_your_key
Enter passphrase for id_ed25519_your_key:
Identity added: id_ed25519_your_key (USERNAME@HOSTNAME)

ssh-add -l
The agent has no identities.

ssh-add -A
No identity found in the keychain.

Ubuntu

ssh-add --help
unknown option -- -
usage: ssh-add [-cDdKkLlqvXx] [-E fingerprint_hash] [-S provider] [-t life]
               [file ...]
       ssh-add -s pkcs11
       ssh-add -e pkcs11
       ssh-add -T pubkey ...

MacOS

ssh-add --help
ssh-add: illegal option -- -
usage: ssh-add [options] [file ...]
Options:
  -l          List fingerprints of all identities.
  -E hash     Specify hash algorithm used for fingerprints.
  -L          List public key parameters of all identities.
  -k          Load only keys and not certificates.
  -c          Require confirmation to sign using identities
  -m minleft  Maxsign is only changed if less than minleft are left (for XMSS)
  -M maxsign  Maximum number of signatures allowed (for XMSS)
  -t life     Set lifetime (in seconds) when adding identities.
  -d          Delete identity.
  -D          Delete all identities.
  -x          Lock agent.
  -X          Unlock agent.
  -s pkcs11   Add keys from PKCS#11 provider.
  -e pkcs11   Remove keys provided by PKCS#11 provider.
  -q          Be quiet after a successful operation.
  -A          Add all identities stored in your keychain.
  -K          Store passphrases in your keychain.
              With -d, remove passphrases from your keychain.

Related terms

• ssh-agent
• ssh-copy-id

See also

• OpenSSH (changelog): /etc/ssh/sshd_config | /etc/ssh/ssh_config | ~/.ssh/ | openSSL | sshd logs | sftp | scp | authorized_keys | ssh-keygen | ssh-keyscan | ssh-add | ssh-agent | ssh | Ssh -O stop | ssh-copy-id | CheckHostIP | UseKeychain, OpenSSF, ~/.ssh/authorized_keys