django/utils/daemonize.py

   1 import os
   2 import sys
   3
   4 if os.name == 'posix':
   5     def become_daemon(our_home_dir='.', out_log='/dev/null',
   6                       err_log='/dev/null', umask=022):
   7         "Robustly turn into a UNIX daemon, running in our_home_dir."
   8         # First fork
   9         try:
  10             if os.fork() > 0:
  11                 sys.exit(0)     # kill off parent
  12         except OSError, e:
  13             sys.stderr.write("fork #1 failed: (%d) %s\n" % (e.errno, e.strerror))
  14             sys.exit(1)
  15         os.setsid()
  16         os.chdir(our_home_dir)
  17         os.umask(umask)
  18
  19         # Second fork
  20         try:
  21             if os.fork() > 0:
  22                 os._exit(0)
  23         except OSError, e:
  24             sys.stderr.write("fork #2 failed: (%d) %s\n" % (e.errno, e.strerror))
  25             os._exit(1)
  26
  27         si = open('/dev/null', 'r')
  28         so = open(out_log, 'a+', 0)
  29         se = open(err_log, 'a+', 0)
  30         os.dup2(si.fileno(), sys.stdin.fileno())
  31         os.dup2(so.fileno(), sys.stdout.fileno())
  32         os.dup2(se.fileno(), sys.stderr.fileno())
  33         # Set custom file descriptors so that they get proper buffering.
  34         sys.stdout, sys.stderr = so, se
  35 else:
  36     def become_daemon(our_home_dir='.', out_log=None, err_log=None, umask=022):
  37         """
  38         If we're not running under a POSIX system, just simulate the daemon
  39         mode by doing redirections and directory changing.
  40         """
  41         os.chdir(our_home_dir)
  42         os.umask(umask)
  43         sys.stdin.close()
  44         sys.stdout.close()
  45         sys.stderr.close()
  46         if err_log:
  47             sys.stderr = open(err_log, 'a', 0)
  48         else:
  49             sys.stderr = NullDevice()
  50         if out_log:
  51             sys.stdout = open(out_log, 'a', 0)
  52         else:
  53             sys.stdout = NullDevice()
  54
  55     class NullDevice:
  56         "A writeable object that writes to nowhere -- like /dev/null."
  57         def write(self, s):
  58             pass