How do you get the process ID of a program in Unix or Linux using Python?

From the standard library:

os.getpid()

If you are not limiting yourself to the standard library, I like psutil for this.

For instance to find all “python” processes:

>>> import psutil
>>> [p.info for p in psutil.process_iter(attrs=['pid', 'name']) if 'python' in p.info['name']]
[{'name': 'python3', 'pid': 21947},
 {'name': 'python', 'pid': 23835}]

For Windows

A Way to get all the pids of programs on your computer without downloading any modules:

import os

pids = []
a = os.popen("tasklist").readlines()
for x in a:
      try:
         pids.append(int(x[29:34]))
      except:
           pass
for each in pids:
         print(each)

If you just wanted one program or all programs with the same name and you wanted to kill the process or something:

import os, sys, win32api

tasklistrl = os.popen("tasklist").readlines()
tasklistr = os.popen("tasklist").read()

print(tasklistr)

def kill(process):
     process_exists_forsure = False
     gotpid = False
     for examine in tasklistrl:
            if process == examine[0:len(process)]:
                process_exists_forsure = True
     if process_exists_forsure:
         print("That process exists.")
     else:
        print("That process does not exist.")
        raw_input()
        sys.exit()
     for getpid in tasklistrl:
         if process == getpid[0:len(process)]:
                pid = int(getpid[29:34])
                gotpid = True
                try:
                  handle = win32api.OpenProcess(1, False, pid)
                  win32api.TerminateProcess(handle, 0)
                  win32api.CloseHandle(handle)
                  print("Successfully killed process %s on pid %d." % (getpid[0:len(prompt)], pid))
                except win32api.error as err:
                  print(err)
                  raw_input()
                  sys.exit()
    if not gotpid:
       print("Could not get process pid.")
       raw_input()
       sys.exit()

   raw_input()
   sys.exit()

prompt = raw_input("Which process would you like to kill? ")
kill(prompt)

That was just a paste of my process kill program I could make it a whole lot better but it is okay.

The task can be solved using the following piece of code, [0:28] being interval where the name is being held, while [29:34] contains the actual pid.

import os

program_pid = 0
program_name = "notepad.exe"

task_manager_lines = os.popen("tasklist").readlines()
for line in task_manager_lines:
    try:
        if str(line[0:28]) == program_name + (28 - len(program_name) * ' ': #so it includes the whitespaces
            program_pid = int(line[29:34])
            break
    except:
        pass

print(program_pid)

Also:
Python: How to get PID by process name?

Adaptation to previous posted answers.

def getpid(process_name):
    import os
    return [item.split()[1] for item in os.popen('tasklist').read().splitlines()[4:] if process_name in item.split()]

getpid('cmd.exe')
['6560', '3244', '9024', '4828']

For posix (Linux, BSD, etc… only need /proc directory to be mounted) it’s easier to work with os files in /proc

Works on python 2 and 3 ( The only difference is the Exception tree, therefore the “except Exception“, which i dislike but kept to maintain compatibility. Also could’ve created 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]:
            # dirname is also the number of PID
            print('{0:<12} : {1}'.format(dirname, ' '.join(content)))

Sample Output (it works like pgrep):

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

With psutil:

(can be installed with [sudo] pip install psutil)

import psutil

# Get current process pid
current_process_pid = psutil.Process().pid
print(current_process_pid)  # e.g 12971

# Get pids by program name
program_name = 'chrome'
process_pids = [process.pid for process in psutil.process_iter() if process.name == program_name]
print(process_pids)  # e.g [1059, 2343, ..., ..., 9645]

This is a simplified variation of Fernando’s answer. This is for Linux and either Python 2 or 3. No external library is needed, and no external process is run.

import glob

def get_command_pid(command):
    for path in glob.glob('/proc/*/comm'):
        if open(path).read().rstrip() == command:
            return path.split('/')[2]

Only the first matching process found will be returned, which works well for some purposes. To get the PIDs of multiple matching processes, you could just replace the return with yield, and then get a list with pids = list(get_command_pid(command)).

Alternatively, as a single expression:

For one process:

next(path.split('/')[2] for path in glob.glob('/proc/*/comm') if open(path).read().rstrip() == command)

For multiple processes:

[path.split('/')[2] for path in glob.glob('/proc/*/comm') if open(path).read().rstrip() == command]