Chapter 8 Processes

Question 1

What command starts an application?

Answer 1

$ nice “name of application”

Question 2

What is a process in the context of operating systems?

Answer 2

A running program

Each process is unique even if the same program is launched multiple times.

Question 3

What does PID stand for in process management?

Answer 3

Process ID

Each process has a unique PID and a PPID (Parent Process ID).

Question 4

What is the first process that starts upon bootup?

Answer 4

systemd

It has a PID of 1.

Question 5

What happens to a child process when it completes its task?

Answer 5

It wakes up the parent process

Data is transferred to the parent, and the memory space of the child becomes a zombie.

Question 6

What are the four types of process states?

Answer 6

• Running
• Sleeping
• Stopped
• Zombie

Each state indicates the current status of a process.

Question 7

What command is used to see the top consuming processes?

Answer 7

top

This command provides a dynamic view of system processes.

Question 8

What command is used to see a list of processes?

Answer 8

ps

Options vary between POSIX and BSD styles.

Question 9

What command shows the hierarchy of processes?

Answer 9

pstree

This command visualizes the relationship between PIDs and PPIDs. Can use pstree -p to show the PIDs for each process.

Question 10

To run a command in the background, you should add _______ to the end of the command line.

Answer 10

&

This allows the command to run without occupying the terminal.

Question 11

What command is used to move a process to the foreground?

Answer 11

fg

You can specify the job number with %<job>.</job>

Question 12

What signal number is the default for stopping a process?

Answer 12

15

This signal tells the process to quit normally but can be ignored.

Question 13

What command is used to kill a process?

Answer 13

kill

You must find the PID of the process before using this command.

Question 14

What does the signal number 9 do when killing a process?

Answer 14

Tells the process to quit immediately, cannot be ignored

This is a forceful termination of the process.

Question 15

What command can you use to kill multiple processes by command name?

Answer 15

pkill

This command can also kill processes by UID or GID.

Question 16

To log a user out, you need to find their PID and use which command?

Answer 16

pkill -P <PID></PID>

This effectively kills the user’s session.

Question 17

What command displays al processes running for all users

Answer 17

$ ps aux

Question 18

What command is used to see options that can be used with the ps command?

Answer 18

$ man ps

Question 19

What command is used to list the different ways to kill a process?

Answer 19

kill -l