processes

Question 1

What are the four possible process states?

Answer 1

Running
Waiting
Stopped
Zombie - A halted process AKA “Terminated State”. Usually only visible because it is being held open by its parent process

Note: “Orphan state” is sometimes mentioned online to help describe zombie state. “Orphan” is not a real process state. Orphan processes are in the state “Running”.

Question 2

What is the process ID of the process that spawns all other processes?

Answer 2

1

this is the init system of course. the PPID of the init process is 0, but this is a placeholder number representing the kernel and does not represent an actual process. Processes are managed by the kernel and the kernel itself is not a process.

Question 3

What component of the operating system manages processes?

Answer 3

The kernel

Question 4

What is PGID?

Answer 4

“Process Group ID” this is the ID of the group and the PID of the Process Group Leader.

This is useful because signals like ‘Term’ can be directed at a group instead of its individual members.

Processes can be grouped by sessions, and processes within a session may be grouped in groups. The sessions and groups have IDs matching the UIDs of their ‘leaders’.

Question 5

What is PPID?

Answer 5

This is the ‘Parent Process ID’ and is the ID of the process that spawned the process in question.

Every process descends from the init system, which has a PID of 1