How to get PID by process name?

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}'

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

To improve the Padraic’s answer: when check_output returns a non-zero code, it raises a CalledProcessError. This happens when the process does not exists or is not running.

What I would do to catch this exception is:

#!/usr/bin/python

from subprocess import check_output, CalledProcessError

def getPIDs(process):
    try:
        pidlist = map(int, check_output(["pidof", process]).split())
    except  CalledProcessError:
        pidlist = []
    print 'list of PIDs = ' + ', '.join(str(e) for e in pidlist)

if __name__ == '__main__':
    getPIDs("chrome")

The output:

$ python pidproc.py
list of PIDS = 31840, 31841, 41942

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()]

If your OS is Unix base use this code:

import os
def check_process(name):
    output = []
    cmd = "ps -aef | grep -i '%s' | grep -v 'grep' | awk '{ print $2 }' > /tmp/out"
    os.system(cmd % name)
    with open('/tmp/out', 'r') as f:
        line = f.readline()
        while line:
            output.append(line.strip())
            line = f.readline()
            if line.strip():
                output.append(line.strip())

    return output

Then call it and pass it a process name to get all PIDs.

>>> check_process('firefox')
['499', '621', '623', '630', '11733']

Since Python 3.5, subprocess.run() is recommended over subprocess.check_output():

>>> int(subprocess.run(["pidof", "-s", "your_process"], stdout=subprocess.PIPE).stdout)

Also, since Python 3.7, you can use the capture_output=true parameter to capture stdout and stderr:

>>> int(subprocess.run(["pidof", "-s", "your process"], capture_output=True).stdout)

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
       break

print("Pid:", pid)

if you’re using windows,
you can get PID of process/app with it’s image name with this code:

from subprocess import Popen, PIPE

def get_pid_of_app(app_image_name):
    final_list = []
    command = Popen(['tasklist', '/FI', f'IMAGENAME eq {app_image_name}', '/fo', 'CSV'], stdout=PIPE, shell=False)
    msg = command.communicate()
    output = str(msg[0])
    if 'INFO' not in output:
        output_list = output.split(app_image_name)
        for i in range(1, len(output_list)):
            j = int(output_list[i].replace(""", '')[1:].split(',')[0])
            if j not in final_list:
                final_list.append(j)

    return final_list

it will return you all PID of a app like firefox or chrome e.g.

>>> get_pid_of_app("firefox.exe")
[10908, 4324, 1272, 6936, 1412, 2824, 6388, 1884]

let me know if it helped

On Unix, you can use pyproc2 package.

Installation

pip install pyproc2

Usage

import pyproc2
chrome_pid=pyproc2.find("chrome").pid #Returns PID of first process with name "chrome"