Linux Administration Analysing Processes

Question 1

every program is run as a _______

Answer 1

process

Question 2

what is a process

Answer 2

instance of a running program

Question 3

command to check the running process

Answer 3

ps

Question 4

what does ps -f do ?

Answer 4

displays the full information of each process, including the user who owns the process and the command line arguments used to start the process.

Question 5

what does ps -fe do ?

Answer 5

It shows all processes running on the system, including those of other users

Question 6

how to show dynamic real-time view of processes and tasks

Answer 6

top

Question 7

what exactly does top show

Answer 7

PID
PR
SHR
VIRT
USER
%CPU
TIME+
NI
%MEM

Question 8

what is PID

Answer 8

Shows task’s unique process id.

Question 9

what is PR

Answer 9

Stands for priority of the task.

Question 10

WHAT IS SHR

Answer 10

Represents the amount of shared memory used by a task.

Question 11

what is VIRT

Answer 11

Total virtual memory used by the task.

Question 12

what is USER

Answer 12

User name of owner of task

Question 13

what is %cpu

Answer 13

Represents the CPU usage.

Question 14

what is time+

Answer 14

CPU Time, the same as ‘TIME’, but reflecting more granularity through hundredths of a second

Question 15

what is NI

Answer 15

Represents a Nice Value of task. A Negative nice value implies higher priority, and positive Nice value means lower priority.

Question 16

what is mem%

Answer 16

Shows the Memory usage of task.

Question 17

check if the vim or bash process i running

Answer 17

ps -fe |egrep “vi|bash”

Question 18

How can you identify conclusively the process ID (PID) for each of the bash shell?

Answer 18

ps -fe | grep “bash”

Question 19

what is a job

Answer 19

display the status of all the background jobs that are running or stopped in the current shell.

Question 20

how to list all jobs

Answer 20

jobs

Question 21

how to start httpd

Answer 21

service httpd start

or

systemctl start httpd

Question 22

how to kill process

Answer 22

kill [process_id]

kill 12593

Question 23

how to bring process to the foreground

Answer 23

fg %[job_number]

Question 24

what are signals

Answer 24

Signals are used to notify a process or thread of a particular event.

Signals are software interrupts.

Question 25

what happens when signal is sent to process/thread

Answer 25

When a signal is sent to a process or thread, it causes the processor to enter an "interrupt" handler, so subsequent processing can be done in the operating system based on the source and cause of the interrupt.

Question 26

command to list the signals to use with the kill command.

Answer 26

kill -l

Question 27

Every type of event is represented by a ______

Answer 27

signal

Question 28

The system defines a __________ to take when a signal occurs

Answer 28

default action

Question 29

what are the 4 types of actions

Answer 29

Exit = Forces the process to exit. Core = Forces the process to exit and create a core file. Stop = Stops the process. Ignore = Ignores the signal and no action taken.

Question 30

what does -9 in kill -9 4241 mean ?

Answer 30

A signal value of 9 means that the signal cannot be caught by the application but is intercepted by operating system to terminate the process.

Question 31

what happens if signal is not specified

Answer 31

If the signal is not specified, by default, the kill command sends signal 15 to terminate a process.