I have an installer that loads an agent into launchd. A whiiiiile back, I read Quinn’s post about Mach bootstrap namespaces and launchd: http://lists.macosforge.org/pipermail/launchd-dev/2010-February/000741.html (In my case, I decided that loading it just for the current user was probably good enough.) Well, I just did an overhaul on the installer and noticed that loading the agent on 10.5 was failing with an error: launch_msg(): Socket is not connected Huh?! All seemed to be well in 10.6 and up. After bashing my head against it for a while, I discovered that a line like this in my installer: su "$USER" -c "launchctl load …" had, in the overhaul, changed to this: sudo -u "USER" launchctl load … Using su fixes the issue. I have no idea what the difference might be. I’m posting this in case anyone else runs into the same problem. Also, I wonder, does anyone has any insight into why they behave differently? Sidney