Detecting application start up with python

We need some information, what did you want to do? Did you wanna know, if a process is started and then you will continue you python script? Than you can do this:

import psutil

def is_process_running(processName):
    for process in psutil.process_iter(): # iterates through all processes from your OS
        try: 
            if processName.lower() in process.name().lower(): # lowers the name, because "programm" != proGramm"
                return True # if the process is found, then return true
        except (psutil.NoSuchProcess, psutil.AccessDenied, psutil.ZombieProcess): # some failures what could go wrong
            pass
    return False;

while(!is_process_running('nameOfTheProcess') # only continue as long as the return is False
    time.sleep(10) # wait 10 seconds

For further information: psutil-docs

This can be achieved in multiple ways, following can also be the one.

import subprocess 
#sub-process library being part of python doesn't
#require any additional installation and can do all the work.


#For Windows operating system we can use 'tasklist'
#in place of 'ps aux' as the first argument
#(haven't work with windows lately but this is close to something i remember).
#check_output api called when shell=true,returns list of running processes.

running_processes = subprocess.check_output(['ps aux'], shell=True)

#check if the application needed is running, for brevity, I am using firefox,
#if yes, it fires off another python script.

if bytes('firefox',encoding='utf-8') in running_processes:
    subprocess.call(['python3', '/path/to/application.py'])
else:
    print('it not')