How to get PID by process name?

Question

Is there any way I can get the PID by process name in Python?

  PID USER      PR  NI  VIRT  RES  SHR S  %CPU %MEM    TIME+  COMMAND                                                                                        
 3110 meysam    20   0  971m 286m  63m S  14.0  7.9  14:24.50 chrome 

For example I need to get 3110 by chrome.

Solution 1

You can get the pid of processes by name using pidof through subprocess.check_output:

from subprocess import check_output
def get_pid(name):
    return check_output(["pidof",name])


In [5]: get_pid("java")
Out[5]: '23366\n'

check_output(["pidof",name]) will run the command as "pidof process_name", If the return code was non-zero it raises a CalledProcessError.

To handle multiple entries and cast to ints:

from subprocess import check_output
def get_pid(name):
    return map(int,check_output(["pidof",name]).split())

In [21]: get_pid("chrome")

Out[21]: 
[27698, 27678, 27665, 27649, 27540, 27530, 27517, 14884, 14719, 13849, 13708, 7713, 7310, 7291, 7217, 7208, 7204, 7189, 7180, 7175, 7166, 7151, 7138, 7127, 7117, 7114, 7107, 7095, 7091, 7087, 7083, 7073, 7065, 7056, 7048, 7028, 7011, 6997]

Or pas the -s flag to get a single pid:

def get_pid(name):
    return int(check_output(["pidof","-s",name]))

In [25]: get_pid("chrome")
Out[25]: 27698

Solution 2

You can use psutil package:

Install

pip install psutil

Usage:

import psutil

process_name = "chrome"
pid = None

for proc in psutil.process_iter():
    if process_name in proc.name():
       pid = proc.pid

Solution 3

For posix (Linux, BSD, etc... only need /proc directory to be mounted) it's easier to work with os files in /proc. It's pure python, no need to call shell programs outside.

Works on python 2 and 3 ( The only difference (2to3) is the Exception tree, therefore the "except Exception", which I dislike but kept to maintain compatibility. Also could've created a custom exception.)

#!/usr/bin/env python

import os
import sys


for dirname in os.listdir('/proc'):
    if dirname == 'curproc':
        continue

    try:
        with open('/proc/{}/cmdline'.format(dirname), mode='rb') as fd:
            content = fd.read().decode().split('\x00')
    except Exception:
        continue

    for i in sys.argv[1:]:
        if i in content[0]:
            print('{0:<12} : {1}'.format(dirname, ' '.join(content)))

Sample Output (it works like pgrep):

phoemur ~/python $ ./pgrep.py bash
1487         : -bash 
1779         : /bin/bash

Solution 4

you can also use pgrep, in prgep you can also give pattern for match

import subprocess
child = subprocess.Popen(['pgrep','program_name'], stdout=subprocess.PIPE, shell=True)
result = child.communicate()[0]

you can also use awk with ps like this

ps aux | awk '/name/{print $2}'

Solution 5

Complete example based on the excellent @Hackaholic's answer:

def get_process_id(name):
    """Return process ids found by (partial) name or regex.

    >>> get_process_id('kthreadd')
    [2]
    >>> get_process_id('watchdog')
    [10, 11, 16, 21, 26, 31, 36, 41, 46, 51, 56, 61]  # ymmv
    >>> get_process_id('non-existent process')
    []
    """
    child = subprocess.Popen(['pgrep', '-f', name], stdout=subprocess.PIPE, shell=False)
    response = child.communicate()[0]
    return [int(pid) for pid in response.split()]

View more solutions

Comments

[Avinash Raj]

+1 seems like a perfect answer. could you explain this return check_output(["pidof",name])

[Padraic Cunningham]

@AvinashRaj, added an explanation, hopefully makes it a little more clear

[ThiefMaster]

Why not go through /proc entries instead of calling external tools? While common in bash scripts, it's usually not very clean to do so in python scripts. Also, what if there are multiple processes with that name? I would at least splitlines() the output and covert the pids to ints.

[Padraic Cunningham]

@ThiefMaster, what is not clean about using the pidof command?

[ThiefMaster]

Is it even available by default on all/most linux systems?

[Padraic Cunningham]

@ThiefMaster, as far as I know yes it is. Also I used split with map to convert to ints and handle the case if there are multiple processes with that name. I still don't get your problem with using the command. parsing the top output will also give multiple process id's

[ThiefMaster]

You could use one of the helper functions in the subprocess module.. much more readable. Also, executing it inside a shell is a really bad idea!

[Hackaholic]

yep its just a concept, I have given to OP

[sobolevn]

it is better to run with shell=False.

[Jaime M.]

Note that check_output() is not available in Python 2.6 and older versions.

[Padraic Cunningham]

@JaimeM., it is pretty trivial to implement gist.github.com/edufelipe/1027906

[Vraj Solanki]

@PadraicCunningham What does it mean when I get the CalledProcessError and how do it fix it to get the process Id. I am trying to make the script and run in OpenWRT.

[Rajan Ponnappan]

In this case, since we aren't going anything useful in try/catch, we can also use subprocess.call rather than subprocess.check_output with try/catch block.

[Alejandro Blasco]

@RajanPonnappan With subprocess.call you only gets the return code ($?), however subprocess.check_output returns what you really want: the command output (in this case, the list of PIDs)

[Rajan Ponnappan]

You are right. I got confused between the behavior of check_call and check_output.

[Dennis Golomazov]

Great answer! I've written a complete example based on it here: stackoverflow.com/a/44712205/304209

[Voldemort's Wrath]

@AvinashRaj Since the poster of this answer has not been active, I turn to you. When I use the first snippet of code, it throws a FileNotFoundError. Why is this?

[Admin]

On Solaris family /proc is binary, not textual.

[Brian Hannay]

@Voldemort'sWrath if you run the snippet on a device without a pidof command such as Windows, the command will not be found. This could be one reason.