Process Management

Question 1

What is a program?

Answer 1

a set of written instructions, stored in a system.

Question 2

Could you explain the concept of a process?

Answer 2

a running instance of a program.

Question 3

What are the various states that Linux processes can assume?

Answer 3

Running
Stopped
Zombie
Sleeping
Terminated
Uninterrupted Sleep

Question 4

Can you elaborate on what interactive processes entail?

Answer 4

a process which acts on user input, example using -f with rm

Question 5

How would you define a daemon process?

Answer 5

a process that is continuously running in the background and manages a particular task or service.

Question 6

What steps allow a process to be moved to the background?

Answer 6

use &amp to send a process
into the background

for e.g. sleep 200 &.

Question 7

How can a process be brought to the foreground?

Answer 7

jobs to get job id. then fg %jobid.

Question 8

Which command is used to inspect background processes?

Answer 8

jobs

Question 9

What purpose does the ps -aux command serve?

Answer 9

indicates the running processes along with the resources they are using. %cpu, %memory, time, state, terminal. unix based command

Question 10

How is it possible to terminate a background process?

Answer 10

jobs -l to get pid/jobid
kill %jobid or
kill -9 pid or kill -15 pid

Question 11

What is the method to list all active processes?

Answer 11

ps -ef

Question 12

Is there a command to display a process and its child processes?

Answer 12

pstree <username> and/or
pgrep -l <processname>

Question 13

How can a process be terminated using its name?

Answer 13

pkill <processname>

Question 14

What sets apart the SIGTERM and SIGKILL signals?

Answer 14

SIGTERM kills the process gracefully, SIGKILL kills the process abruptly or forcefully.

Question 15

Which signal enables a process to continue running even after the shell exits?

Answer 15

nohup – no hang
up.

Question 16

What is a zombie process, and how does it occur?

Answer 16

a terminated child process that remains in the system’s process table while waiting for its parent process to collect its exit status

Question 17

Could you elucidate the distinctions between processes and threads?

Answer 17

processes are heavy
weight (more resources), processes do not share memory

threads share resources, memory,
threads are lighter (less resources). threads are a part of process.

Question 18

What approach would you use to search for the "httpd" process among active processes?

Answer 18

ps -
ef | grep httpd or pgrep -l httpd

Question 19

How can you determine the total count of active processes on the system?

Answer 19

ps -ef | wc -l

Question 20

In gracefully terminating a process, which signal is invoked by -15?

Answer 20

SIGTERM

Question 21

For abruptly ending a process, which signal is typically employed?

Answer 21

SIGKILL

Question 22

What is the intended purpose of the pkill command?

Answer 22

kills the process by name.

Question 23

How might one list all processes associated with the user "robert"?

Answer 23

ps -ef
| grep <username>

Question 24

Are you familiar with the concept of the OOM Killer and its intended purpose?

Answer 24

processes utilize memory, system crashes if memory is full, to avoid this system crash there is a phenomenon called Out Of Memory – it will kill the process that is least active and taking up memory, kills the process to create memory for important processes. it kills according to the nice value. usually OOM killer is kept inactive. a mechanism in place in the system, when the system runs out of RAM, it kills unnecessary processes.