Comment #9 on issue 359 by allber...@gmail.com: shellPromptHere from XMonad.Actions.SpawnOn doesn't work as claimed http://code.google.com/p/xmonad/issues/detail?id=359 If it needs to look for children of the spawned process, two possibilities occur to me: (a) use ps; assume POSIX compliance, or test for BSDish vs. POSIX (b) there are portable libraries for this kind of thing, although the dependencies may get interesting (the most portable one I can think of is libgtop...). Off the top of my head, various Unix-like OSes and the normal ways to get at this information: * Solaris: libkvm or /proc (note that /proc is not the same as on Linux or *BSD) * *BSD, OS X: sysctl; libkvm is available for the *BSDs but not OS X * Linux: /proc; libkvm is available libkvm has the difficulty that it usually requires setgid kmem, so you'd need a setgid helper program. It would be better, both for this and for startup notification in desktop managers, if someone had had the sense to recognize that a variant of _NET_WM_PID that recorded and passed on the pid of the original process would be useful, but the free desktop folks seem to have missed that notion. (Hm; maybe the way to go from here is to look at how desktop managers do startup notification and borrow that. I believe it's a freedesktop.org standard.) http://standards.freedesktop.org/startup-notification-spec/startup-notificat... There's also a reference implementation which might be worth interfacing to or reimplementing in Haskell.