by James Hunt, Clint Byrum. 2014-07-17. Upstart is an event-based replacement for the /sbin/init daemon which handles starting of tasks and services during boot, stopping them during shutdown and supervising them while the system is running. The "init" or "system initialisation" process on Unix and Linux systems has process ID (PID) "1". That is to say, it is the first process to start when the system boots.