how to get all process information in linux?

Question

I want to get all process information in a linux server.
PID, USER, CPU% , COMMAND ...
Exactly, I want to get these information in a python script. I tried
a,b = commands.getstatusoutput('top -n 1')
This gave me about 20 rows of results ordered by CPU%, but I want more, about 40 or 50 rows of results.

How should I do?

I use psutil as follow, for each proc, it need to wait 1 second. How can I get cpu_percent like top command quickly.

for proc in psutil.process_iter():
    try:
        pinfo = proc.as_dict(attrs=['pid', 'username', 'cpu_percent', 'name'])
        pinfo['cpu_percent'] = proc.cpu_percent(interval=1)
        if pinfo['cpu_percent'] > 0:
            print(pinfo)
        except psutil.NoSuchProcess:
            pass

Read [proc(5)](http://man7.org/linux/man-pages/man5/proc.5.html) — Basile Starynkevitch, Nov 08 '16 at 06:17
Actually I read the manual of top, but I misunderstood the function of "top -b". nexus66 gives me the right answer. — Swind D.C. Xu, Nov 08 '16 at 06:20

score 2 · Answer 1 · answered Nov 08 '16 at 05:02

2

Instead of calling an external process like top, build the info yourself. Check out the psutil library. It should give you all the data you need.

answered Nov 08 '16 at 05:02

zenlc2000

451
4
9

It is easy to use, but when I use pinfo = proc.as_dict(attrs=['pid', 'username', 'cpu_percent', 'name']), cpu_percent returns 0.0 – Swind D.C. Xu Nov 08 '16 at 05:48
Are you sure the cpu percent was greater than 0? – zenlc2000 Nov 08 '16 at 05:52
I test for all running proc, so at least one proc is greater than 0. – Swind D.C. Xu Nov 08 '16 at 05:54
What interval value are you using? – zenlc2000 Nov 08 '16 at 05:57
http://stackoverflow.com/questions/24367424/cpu-percentinterval-none-always-returns-0-regardless-of-interval-value-python – zenlc2000 Nov 08 '16 at 05:58
The default value is None, so it returns 0. But when I set interval value to 1, the program is too slow. How could I speed up it. – Swind D.C. Xu Nov 08 '16 at 06:00
Hmmm... without seeing your code or knowing why you need it faster, I can only give generalities. Read less data, use Numpy for storing data, use pypy, do jit compiling with numba (library from Continuum Analytics), etc. – zenlc2000 Nov 08 '16 at 06:05

Chiheb Nexus · Accepted Answer · 2016-11-08T06:29:13.587

I recommend you using psutil library like what zenlc2000 said in his comment. However, you can use the output of top's command.

You have also to take a look at top command's manual or simply writing man top in your terminal.

I give you an example of using top command's output within Python3 (or Python2):

Let's suppose i want to know top command's output for gedit:

$ top -b n 1 | grep gedit

Output:

8381 nexus   20   0  565928  43696  30268 S   0,0  1,1   0:06.03 gedit

In order to understand the output i'll write it with the keys:

 PID  UTIL     PR    NI    VIRT     RES    SHR   S  %Cpu %MEM TEMPS+   COM.
 8381 nexus    20    0     565928   43696  30268 S  0,0  1,1  0:06:03  gedit

Now, we'll filer the output with awk:

$ echo -n "%CPU: " && top -b n 1 | grep gedit | awk '{print $9}'

Output:

%CPU: 0,0

Or simply:

$ top -b n 1 | grep gedit | awk '{print $9}'

Output:

0,0

Using Python3 (or any version you want) in your terminal:

$ python3
>>> import subprocess
>>> proc = subprocess.Popen("top -b n 1 | grep gedit | awk '{print $9}'", shell = True, stdout=subprocess.PIPE)
>>> p = proc.communicate()
>>> p[0].decode("utf8").replace("\n","")

Output:

0,0

And here you go! You got gedit process percentage using Python3 and the output of top command.

You can repeat this process to get all the informations you want from top's output.

Thank you, "-b" is what I need. I read the manual of top before, but I misunderstood the function of "-b". — Swind D.C. Xu, Nov 08 '16 at 06:18

how to get all process information in linux?

How should I do?

2 Answers2