When my pkg runs its Post-installation script, how can I know how that happened?

Question

There are two ways this script can be run: When the user opens the pkg file and goes through the normal GUI setup, or when an admin (or savvy user) runs sudo installer -pkg /path/to/Installer.pkg -target /. For the second one, I want to know when the script was run in this mode so I can make more admin-friendly decisions like not opening another GUI. How do I know when my pkg is installed via the command line?

I'm hoping for some environment variable or something similar.

Answer 1

Since this was being run by the installer command, the COMMAND_LINE_INSTALL environment variable is set to 1. When opening the pkg normally, this variable is not set at all.

So:

if [ $COMMAND_LINE_INSTALL ]; then 
    # Do stuff for CLI land
else
    # Do stuff for GUI land
fi