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CS 3733 Operating Systems Notes: Processes
(change semester)


What is a process?
A process is a program in execution.
A process is a unit of work in a system.
Many processes can execute concurrently.

More specifically, a squential process consists of: Note: Many processes may be associated with a single program.

Process State
States of a sequential process:
invalid transitions


On a single processor system, only one process may be running at any time.

Process Control Block
The OS keeps track of processes via a process control block for each process.
The process control block may contain the following: In UNIX a process can create another process using fork.
The new process (the child) consists of a copy of the address space of the creating process (the parent).
Both processes continue execution at the instruction after the fork. The fork returns 0 to the child and non-zero (the PID) to the parent.
after fork

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