Ensuring a single instance of an application in Linux

import fcntl
pid_file = 'program.pid'
fp = open(pid_file, 'w')
try:
    fcntl.lockf(fp, fcntl.LOCK_EX | fcntl.LOCK_NB)
except IOError:
    # another instance is running
    sys.exit(0)

name = "MyApp-%s" % wx.GetUserId()
  checker = wx.SingleInstanceChecker(name)
  if checker.IsAnotherRunning():
      return False

linux# pidof myapp
8947
linux# pidof nonexistent_app

linux#

import os
os.getpid()

cmd = "ps -p %s -o comm=" % var_run_pid
app_name = os.popen(cmd).read().strip()
if len(app_name) > 0:
    Already running