Man page 1 : ssh-add

ssh-add - adds RSA or DSA identities to the authentication agent

ssh-add [-cDdLlXx] [-t life ] .Op Ar ssh-add - s Ar pkcs11 ssh-add - e Ar pkcs11

adds RSA or DSA identities to the authentication agent, ssh-agent(1) . When run without arguments, it adds the files .Pa ~/.ssh/id_rsa , .Pa ~/.ssh/id_dsa and .Pa ~/.ssh/identity . After loading a private key, will try to load corresponding certificate information from the filename obtained by appending .Pa -cert.pub to the name of the private key file. Alternative file names can be given on the command line.

If any file requires a passphrase, asks for the passphrase from the user. The passphrase is read from the user's tty. retries the last passphrase if multiple identity files are given.

The authentication agent must be running and the SSH_AUTH_SOCK environment variable must contain the name of its socket for to work.

Any keys recorded in the blacklist of known-compromised keys (see ssh-vulnkey(1) ) will be refused.

The options are as follows:

-tag -width Ds
-c Indicates that added identities should be subject to confirmation before being used for authentication. Confirmation is performed by the SSH_ASKPASS program mentioned below. Successful confirmation is signaled by a zero exit status from the SSH_ASKPASS program, rather than text entered into the requester.
-D Deletes all identities from the agent.
-d Instead of adding identities, removes identities from the agent. If has been run without arguments, the keys for the default identities will be removed. Otherwise, the argument list will be interpreted as a list of paths to public key files and matching keys will be removed from the agent. If no public key is found at a given path, will append .Pa .pub and retry.
-e pkcs11 Remove keys provided by the PKCS#11 shared library pkcs11 .
-L Lists public key parameters of all identities currently represented by the agent.
-l Lists fingerprints of all identities currently represented by the agent.
-s pkcs11 Add keys provided by the PKCS#11 shared library pkcs11 .
-t life Set a maximum lifetime when adding identities to an agent. The lifetime may be specified in seconds or in a time format specified in sshd_config(5) .
-X Unlock the agent.
-x Lock the agent with a password.

-tag -width Ds
Ev "DISPLAY" and "SSH_ASKPASS" If needs a passphrase, it will read the passphrase from the current terminal if it was run from a terminal. If does not have a terminal associated with it but DISPLAY and SSH_ASKPASS are set, it will execute the program specified by SSH_ASKPASS and open an X11 window to read the passphrase. This is particularly useful when calling from a .Pa .xsession or related script. (Note that on some machines it may be necessary to redirect the input from .Pa /dev/null to make this work.)
Ev SSH_AUTH_SOCK Identifies the path of a .Ux Ns -domain socket used to communicate with the agent.

-tag -width Ds
Pa ~/.ssh/identity Contains the protocol version 1 RSA authentication identity of the user.
Pa ~/.ssh/id_dsa Contains the protocol version 2 DSA authentication identity of the user.
Pa ~/.ssh/id_rsa Contains the protocol version 2 RSA authentication identity of the user.

Identity files should not be readable by anyone but the user. Note that ignores identity files if they are accessible by others.

Exit status is 0 on success, 1 if the specified command fails, and 2 if is unable to contact the authentication agent.

ssh(1) , ssh-agent(1) , ssh-keygen(1) , ssh-vulnkey(1) , sshd(8)

OpenSSH is a derivative of the original and free ssh 1.2.12 release by Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo de Raadt and Dug Song removed many bugs, re-added newer features and created OpenSSH. Markus Friedl contributed the support for SSH protocol versions 1.5 and 2.0.