[linux-audio-user] scheduling and playback automation

I am new(ish) to this list so hello, been listen for a week or so. I am looking for a the type of software I found in at sharewaremusic.com for scheduling and automation of radio shows. There are a few options in the Windows category, but I have found nothing for Linux, and nothing GPLd. I am hoping that such software would be useful for running a stage productions audio sound effects, with the sound operatator reading the cues from an on-screen running sheet, and triggering the associated sound. He's the part I need most: If, becuase of the timings of cues, the asssociated sounds overlap, they should be mixed together and played back though the same output device. Audio samples would be fairly well prepared, but a simple way to set the overall playback level of an individual same would be ideal. Timing accuracy is not enormously important, so ability to work with a low latancy kernel is not necessarily a requirement. Do you know if such an thing exists for Linux? Thanks Richard