"ps"
command
ps - process status is used to see the status of running processes.
when noting is running and we enter "ps" then it displays :
PID TTY
TIME CMD
4443 pts/1 00:00:00 bash
4551 pts/1
00:00:00 ps
Where ,
PID : is process ID
TTY : is the name of the console
or terminal into which the user is logged .
TIME : TIme in minute and seconds the process is
being running in the CPU.
CMD is the name of the command that initiated the process .
Let's run below jobs and check with "ps" :
Job1:
sleep 100 & click ENTER , it displays below information :
[1] 7642 ---- These are job number[1] and process ID (PID-7642)
job2:
sleep 105 &
click ENTER
[2] 7643
Check the status of the jobs by ENTERING the command "jobs" :
job click ENTER
[1]- Running sleep 100 &
[2]+ Running sleep 105 &
Now let's check process status with
the command "ps" :
ps click ENTER.
OutPut:
PID TTY TIME CMD
4443 pts/1 00:00:00 bash
7642 pts/1 00:00:00 sleep --- first sleep command
7643 pts/1 00:00:00 sleep --- second sleep command
7657 pts/1 00:00:00 ps
To
see all the running/active process : ps -e or ps -A
ps -e click ENTER
Output :
PID TTY TIME CMD
1 ? 00:00:03 init
2 ? 00:00:00 migration/0
.
.
3153 ? 00:00:00 hcid
3159 ? 00:00:00 sdpd
3181 ? 00:00:00 krfcommd
3219 ? 00:00:02 pcscd
.
.
4440 ? 00:00:04
gnome-terminal
4442 ? 00:00:00 gnome-pty-helpe
4443 pts/1 00:00:00 bash
7642 pts/1 00:00:00 sleep
7643 pts/1 00:00:00 sleep
7658 pts/1 00:00:00 ps
To see the full list of all running processes : ps -ef
OutPut:
UID PID PPID C
STIME TTY TIME CMD
root 1 0 0
Mar09 ? 00:00:03 init [5]
root 2 1 0
Mar09 ? 00:00:00 [migration/0]
68 3
1 0 Mar09 ? 00:00:00 [ksoftirqd/0]
.
.
xfs 4437
1 0 Mar09 ? 00:00:00 gnome-screensaver
ram 4440 1 0
Mar09 ? 00:00:04 gnome-terminal
ram 4442 4440 0
Mar09 ? 00:00:00 gnome-pty-helper
ram 4443 4440 0
Mar09 pts/1 00:00:00 bash
ram 7642 4443 0
00:26 pts/1 00:00:00 sleep 100
ram 7643 4443 0
00:26 pts/1 00:00:00 sleep 105
ram 7659 4443 0
00:26 pts/1 00:00:00 ps -ef
To
search the process with a filter , you can use any filter from :
UID , PID , PPID , C ,STIME TTY TIME
CMD
such as :
ps -ef | grep ram
ps -ef | grep 4440
ps -ef | grep screensaver
ps -ef | grep 00:00:04
Kill
Process/Job
you can kill a running process/job by using "kill" command alongwith
its PID :
Let's run sleep 1000& and then kill it :
sleep 1000& click ENTER , after you click ENTER you get
below information :
[1] 9019 where [1]
is the job number and 9019 is the process ID - PID
You can also get the PID using : ps or ps -e
or ps -ef
such as ,
if you click "ps" , you get below informaiton :
PID TTY
TIME CMD
4443 pts/1 00:00:00 bash
9019
pts/1 00:00:00 sleep ---- this the job/process which we need to
kill.
9048 pts/1 00:00:00 ps
"
kill " or " kill
-9 "
Syntax :
kill PID click ENTER
kill 9019 click ENTER
now check the status of the job sleep 1000&
by
using : jobs or ps or ps -e
or ps -ef
if you check the status with the command : "jobs',
it will show " Terminated " :
[1]+ Terminated sleep 1000
if you check with the command "ps",
it will not show the job/process like below :
PID TTY TIME CMD
4443 pts/1 00:00:00 bash
9218 pts/1 00:00:00 ps
In many situations , the job will not be terminated/killed with only "kill" command. In such
situation use "-9" with "kill".
kill -9 PID
click ENTER --- this is killing
the job/process forcefully.
kill -9 9019
click ENTER
Now, if you check the status with the command job, it shows "killed" :
[1]+ Killed sleep 1000
if you check with the command "ps",
it will not show the job/process like below :
PID TTY TIME CMD
4443 pts/1 00:00:00 bash
9218 pts/1 00:00:00 ps
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