Growl’s installer helpfully includes a postflight script that opens up the System Preferences app so that you can configure the Growl options. This is generally what you want most of the time, but not all the time.
If you’re installing Growl through something like ARD, or using an InstaDMG workflow it’s annoying to have the System Preferences app come up when Growl is being installed.
It used to be relatively easy to fix this as Growl was in a package bundle, but now it’s distributed as a flat package. Fortunately, it’s pretty easy to expand a flat package, edit the necessary postflight script and compress it all back together again:
pkgutil --expand Growl.pkg Growl
Edit Growl/growl.pkg/Scripts/postflight and change it to the following (add the first and last lines)
if [ "$3" = "/" ]; then
# Open GHA first so that, hopefully, Growl will already be running when the user lands in the prefpane.
Finally, put it all back together again
pkgutil --flatten Growl Growl121.pkg