usage: ssh-keygen [options]
Options:
-A Generate non-existent host keys for all key types.
-a trials Number of trials for screening DH-GEX moduli.
-B Show bubblebabble digest of key file.
-b bits Number of bits in the key to create.
-C comment Provide new comment.
-c Change comment in private and public key files.
-e Export OpenSSH to foreign format key file.
-F hostname Find hostname in known hosts file.
-f filename Filename of the key file.
-G file Generate candidates for DH-GEX moduli.
-g Use generic DNS resource record format.
-H Hash names in known_hosts file.
-h Generate host certificate instead of a user certificate.
-I key_id Key identifier to include in certificate.
-i Import foreign format to OpenSSH key file.
-L Print the contents of a certificate.
-l Show fingerprint of key file.
-M memory Amount of memory (MB) to use for generating DH-GEX moduli.
-m key_fmt Conversion format for -e/-i (PEM|PKCS8|RFC4716).
-N phrase Provide new passphrase.
-n name,... User/host principal names to include in certificate
-O option Specify a certificate option.
-P phrase Provide old passphrase.
-p Change passphrase of private key file.
-q Quiet.
-R hostname Remove host from known_hosts file.
-r hostname Print DNS resource record.
-S start Start point (hex) for generating DH-GEX moduli.
-s ca_key Certify keys with CA key.
-T file Screen candidates for DH-GEX moduli.
-t type Specify type of key to create.
-V from:to Specify certificate validity interval.
-v Verbose.
-W gen Generator to use for generating DH-GEX moduli.
-y Read private key file and print public key.
-z serial Specify a serial number.