A script that requires root privileges needs to be executed when a non-root privileged user signs in/out. How do I handle this?
Use the PAM session hooks module.
lightdm, the display manager in Ubuntu allows running session setup scripts as root if you add appropriate entry to
/etc/lightdm/lightdm.conf file (Note, that this file doesn't exist as of 14.04, you have to manually create it).
Example of how it might look like
[SeatDefaults] # session-setup-script = Script to run when starting a user session (runs as root) session-setup-script=/opt/myscripts/print_hello.sh # session-cleanup-script = Script to run when quitting a user session (runs as root) session-cleanup-script=/opt/myscripts/print_hello.sh