Efficient Python Daemon

Question

I was curious how you can run a python script in the background, repeating a task every 60 seconds. I know you can put something in the background using &, is that effeictiv

Answer 1

Using & in the shell is probably the dead simplest way as Greg described.

If you really want to create a powerful Daemon though, you will need to look into the os.fork() command.

The example from Wikipedia:

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import os, time

def createDaemon():
  """ 
      This function create a service/Daemon that will execute a det. task
  """

  try:
    # Store the Fork PID
    pid = os.fork()

    if pid > 0:
      print 'PID: %d' % pid
      os._exit(0)

  except OSError, error:
    print 'Unable to fork. Error: %d (%s)' % (error.errno, error.strerror)
    os._exit(1)

  doTask()

def doTask():
  """ 
      This function create a task that will be a daemon
  """

  # Open the file in write mode
  file = open('/tmp/tarefa.log', 'w')

  # Start the write
  while True:
    print >> file, time.ctime()
    file.flush()
    time.sleep(2)

  # Close the file
  file.close()

if __name__ == '__main__':

  # Create the Daemon
  createDaemon()

And then you could put whatever task you needed inside the doTask() block.

You wouldn't need to launch this using &, and it would allow you to customize the execution a little further.