no graceful handling of empty fork command

[Chris Jones]

If, for whatever reason, the command we wish to fork turns out to be "" (e.g. they have a custom command enabled, but not configured, or their user is just plain broken), we will merrily try to fork '', which obviously fails.
One user already has appeared who has an empty system shell (!!!!).
We should try and fallback gracefully to bash and then sh

[Chris Jones (cmsj)]

per passwd(5), the command interpreter field of gecos is optional, so we absolutely must handle this, although they recommend immediately falling back to sh.

[Chris Jones (cmsj)]

This is fixed by commit 253, with a bonus commit (254) to bail out when a shell fails to spawn.. Bailing out the whole program is probably a bad idea though, so this might want to be reverted/changed in future.

[Chris Jones (cmsj)]

commit 255 solves the failing situation properly - instead of exiting the entire application, just the terminal that failed to spawn a shell will close.