What does `ssh-keygen` do? Flags & examples explained

ssh-keygen examples, explained

$ ssh-keygen -t ed25519 -C you@example.com

ssh-keygengenerate, manage and convert SSH authentication keys
-ttype of key to create (ed25519, rsa, ecdsa)
ed25519value for -t
-Ccomment to attach to the key (often your email)
you@example.comvalue for -C

$ ssh-keygen -R oldhost

ssh-keygengenerate, manage and convert SSH authentication keys
-Rremove all keys for the given hostname from known_hosts
oldhostvalue for -R

$ ssh-keygen -y -f id_rsa

ssh-keygengenerate, manage and convert SSH authentication keys
-yread a private key and print its public key
-fkey file to write to or read from
id_rsavalue for -f

ssh-keygen flags & options

-t	type of key to create (ed25519, rsa, ecdsa)
-b	number of bits in the key
-C	comment to attach to the key (often your email)
-f	key file to write to or read from
-N	new passphrase for the key ('' means no passphrase)
-p	change the passphrase of an existing private key
-y	read a private key and print its public key
-l	show the fingerprint of a key file
-R	remove all keys for the given hostname from known_hosts
-F	search known_hosts for the given hostname
-q	quiet — suppress the usual output

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