[Python: Check Existence in PATH] #shell #shutil #subprocess #path #which #python

which.py

#!/usr/bin/env python3

import shutil, subprocess

cmd = shutil.which("python3")
try:
	runner = subprocess.run(cmd, check=True)
except subprocess.CalledProcessError as e: # python3 is not found in path
    print(str(e))
    exit(1)

#####
runner = subprocess.run([cmd, "--version"], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL) # --> Python 3.7.3
runner.resultcode # --> 0

runner = subprocess.run([cmd, "--version"], shell=True, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
runner.resultcode # --> 127; fails bc shell=True is similar to calling `sh python3 --version` which will error