Comment 1 for bug 115152

Addressing your comments in reverse order: the -U option is used to connect the sooperlooper engine to an extant slgui session for OSC control. I'm not sure why it's undocumented, and it probably shouldn't segfault when it fails, but that's somewhat expected behaviour (although still a bug).

As for slgui failing to start could you post the error you receive in the console? For me, slgui only fails to start the engine if I don't previously have jackd running.