Right, I should have said. EDIT: Topological sorting is one of those tools that really comes in handy -- it's easy enough to implement, but I didn't want to sp

Right, I should have said. EDIT: Topological sorting is one of those tools that really comes in handy -- it's easy enough to implement, but I didn't want to spend the time either (a) writing it in zsh or (b) rewriting the rest of the shell pipeline in Python or something. 'tsort' to the rescue! I just wish I could remember where I read about it so I could go buy whoever was at the other end of the Google search a beer.