kill, pkill, killall

What is difference between ps and jobs command?

ps command is used to see the process of the current user it shows processes PID and their names and which terminal they were execute and time.

jobs command shows only process state/status and their commands and names.

Kill commands is used to kill processes/jobs it has two important flags

kill -9  is called SIGKILL

Kill -15 is called SIGTERM

1. kill is used to kill the processes/jobs by their Process ID (PID)
2. pkill is used to kill process/jobs by their name
3. killall also use to to kill processes who have same names

create jobs then use ps to see the PID

[root@geeks ~]# sleep 326718 &

[1] 5480

[root@geeks ~]# sleep 789 &

[2] 5481

[root@geeks ~]# dd if=/dev/zero of=/dev/null &

[3] 5496

[root@geeks ~]# dd if=/dev/zero of=/dev/null &

[4] 5499

[root@geeks ~]# dd if=/dev/zero of=/dev/null &

[5] 5500

[root@geeks ~]# sleep 784  &

[6] 5501

[root@geeks ~]# ps

    PID TTY          TIME CMD

   5480 pts/3    00:00:00 sleep

   5481 pts/3    00:00:00 sleep

   5496 pts/3    00:00:02 dd

   5499 pts/3    00:00:02 dd

   5500 pts/3    00:00:01 dd

   5501 pts/3    00:00:00 sleep

1.Kill -9 & kill -15 

[root@geeks ~]# kill -15 5480

[1]   Terminated              sleep 326718

[root@geeks ~]# kill -9 5499

[4]   Killed                  dd if=/dev/zero of=/dev/null

2.pkill

[root@geeks ~]# pkill sleep

[2]   Terminated              sleep 789

[6]+  Terminated              sleep 784

3.killall

[root@geeks ~]# killall dd

[3]-  Terminated              dd if=/dev/zero of=/dev/null

[5]+  Terminated              dd if=/dev/zero of=/dev/null