I've written a shell script that chooses which browser I would prefer to run based on what's available on my machine. In my xmonad.hs I use readProcess to get the name at startup, and then bind a key to running that name. On my Solaris machine, with an older GHC, this works perfectly, but on my Ubuntu machine with a newer GHC it gives an error at startup: xmonad-x86_64-linux: waitForProcess: does not exist (No child processes) Maybe it tries to get the pid of the child after launching the script but it executes too fast? Here's the snippet from xmonad.hs: main = do home_folder <- getEnv "HOME" editor <- getEditor browser_name <- (readProcess (joinPath [home_folder, "etc/utils/pick_best_browser"]) ["-n"] []) xmonad $ defaults editor home_folder ((head . lines) browser_name) The script when I run it gives this output: /usr/bin/chromium-browser And when I run it with the -n flag like I'm passing above: chromium-browser Which is exactly the output I expect. Since it all works fine on a another box I don't think it's anything wrong with the script -- I figured it could be an environment problem but it only relies on $HOME. Any ideas? Thanks, Joe G.