Python3 script monitoring if a process is running and logging the time when the process has stopped. It works for one or multiple instances of the same process.

proc_monitor.sh

#!/usr/bin/env python3

''' Script checking if a pre-defined process is running '''
import subprocess
import shlex
import time
import datetime
import psutil
import os

proc_name = "<proc_name>"
home_dir = os.getenv('HOME')
log_dir = os.path.join(home_dir, "logs")
log_name = datetime.datetime.now().strftime("%Y%m%d_process_log.txt")
log_file = os.path.join(log_dir, log_name)

def dir_creation(dir_name):
    if not os.path.isdir(log_dir):
        os.mkdir(dir_name)

def delete_log(log_file):
    if os.path.isfile(log_file):
        os.remove(log_file)

def proc_monitor(proc_name, log_file):
    try:
        grep_cmd = "pgrep -a " + proc_name
        proc_run = subprocess.check_output(shlex.split(grep_cmd)).decode('utf-8')
        proc_run = proc_run.strip().split('\n')
        '''
        Creating a dictionary with key the PID of the process and value
        the command line
        '''
        proc_dict = dict(zip([i.split(' ', 1)[0] for i in proc_run],
                             [i.split(' ', 1)[1] for i in proc_run]))

        while proc_dict:
            for key, value in proc_dict.items():
                if psutil.pid_exists(int(key)):
                    time.sleep(3)
                else:
                    # print(f"PID: {key} of command: \"{value}\" stopped at {datetime.now().strftime('%d-%m-%Y %T')}")
                    with open(log_file, "a+") as log:
                        log.write(f"PID: {key} of command: \"{value}\" stopped at {datetime.datetime.now().strftime('%d-%m-%Y %T')}\n")
                    del proc_dict[key]
                    break
    # Check if the proc_name is actually running on the machine
    except subprocess.CalledProcessError as e:
        print(f"The \"{proc_name}\" command isn't running on this machine")

dir_creation(log_dir)
delete_log(log_file)
proc_monitor(proc_name, log_file)