It’s not THAT much trouble to update your .ssh/config file every time a host changes, but when it starts happening often enough, even that hassle starts to add up. This is a quick tool I wrote to help handle them.

It takes great care to not trash your config file, so you can continue to edit your config files by hand before and after running the tool.

ssh-config will make a backup of your ~/.ssh/config file as ~/.ssh/config~.

Probably the most useful command is “copy”, which intelligently copies an existing host section.

Adds or updates the value for a given host.

Removes a key value for a given host. NOTE: If all values are removed from a section, the section is NOT removed; use rm <host> for that.

Removes an entire host section.

Copies the entire section named <old_host> to a new section called <new_host>. If old_host has a Hostname section, ssh-config will try to update it to reflect the new_host name. For example, if you had a section like

Host rails01
  Hostname rails01.example.com

And you did ssh-config copy rails01 rails02, the new section would look like this:

Host rails02
  Hostname rails02.example.com

You can manually override any setting, and/or set new ones by appending the new key/value pairs at the end. Given the rails01 section above, “ssh-config copy rails01 rails02 Hostname rails-02.example.com User dbrady” would emit

Host rails02
  Hostname rails-02.example.com
  User dbrady

Note: If you just want another short name for a host, use alias instead

Dumps the entire file.

Dumps one section. (Similar to ssh-what.) <host> may be the main name for a host or an alias.

Shows all sections that have any line (key OR value) that matches pattern. (Similar to ssh-what.)

Lists all section names (just the Host line)

Adds one or more aliases to a host definition (to show up on the Host line).

With 2 or more arguments, looks up host by <host> (must be the first name on the Host line), and removes any <alias>es from the list of alternate names. With only 1 argument, looks for an entry by that alias (must NOT be the first name on the Host line), and removes the alias from the entry, if found.