restartBT

#!/usr/bin/python3
"""
NB  restart requires that BT is on PATH
    and  export PYTHONPATH=/path/to/Vcourse/lib  is needed
    and  the working directory needs to have config files,
    so the restart is attempted in the original dir which
    is the second line of the pid file.
    If the pid file does not exist (hopefully the process is 
    not running) then start is attempted in the pwd.
"""

# License GPL 2. Copyright Paul D. Gilbert, 2018

import os 
import signal 
import time 
import sys
import subprocess

pidfile = os.getenv("HOME") + '/.BT.pid'

pid = ['', os.getenv("PWD")] # for case process is not running 

try:
   with open(pidfile, 'r') as f: pid = f.read().splitlines()
except:
   print('pid file ' + pidfile+ ' read error. Process probably not running.')

try:
   os.kill(int(pid[0]), signal.SIGTERM)
   os.remove(pidfile)
   time.sleep(5)
except:
   print('kill failed. Process probably not running.')
   print('will attempt to start process in pwd.')

npid = subprocess.Popen('BT', cwd=pid[1]).pid
print(npid)