Remove offending key from known_hosts file with one swift move

 $ ssh-keygen -R <hostname>

Jan. 25, 2014, 1:35 p.m. — openiduser126

Explanation

The ssh-keygen tool comes with an option for this already, there is no need for esoteric one-liners that are hard to remember.

Say you ssh server.example.com and its host key has changed because you just reinstalled it. Run ssh-keygen -R server.example.com then try to connect to the server again, you'll be presented with the option to save the host key just like new.

Related one-liners

Remove offending key from known_hosts file with one swift move

 $ sed -i 18d .ssh/known_hosts

Jan. 16, 2013, 2:29 p.m. — EvaggelosBalaskas

Explanation

Using sed to remove a specific line.

The -i parameter is to edit the file in-place.

Limitations

This works as posted in GNU sed. In BSD sed, the -i flag requires a parameter to use as the suffix of a backup file. You can set it to empty to not use a backup file:

sed -i'' 18d .ssh/known_hosts