When sudoing/suing/etc, how do the various user-ID indicators get set?
|real UID||effective UID||TTY owner1 2||$SUDO_USER|
("new" is the user that the script runs as, "old" is what the user originally logged in as)
1 as determined by running who am i or logname
2 This data is unavailable if there's no TTY (for instance, when running under 'cron' or under a web server)
3 unless stay_setuid is specified in /etc/sudoers