The eXpOS Process Model

A program under execution is called a process. A process is newly created when a process already in execution invokes the Fork system call. The first process, the INIT process, is created by the OS during bootstrap by loading a code stored in a pre-defined disk location to memory and setting up a process. The OS assigns a unique integer identifier called process id for each process when it is created. The process id does not change during the lifetime of the process. The process that creates the new process is called the parent process of the newly created process.

* In Multiuser implemention of eXpOS, each process is assigned a userid corresponding to the currently logged in user.