如何使用Python守护进程和脚本？

#!/usr/bin/env python 
#coding: utf-8 
import sys, os 
 
'''将当前进程fork为一个守护进程 
 注意：如果你的守护进程是由inetd启动的，不要这样做！inetd完成了 
 所有需要做的事情，包括重定向标准文件描述符，需要做的事情只有chdir()和umask()了 
''' 
 
def daemonize (stdin='/dev/null', stdout='/dev/null', stderr='/dev/null'): 
  #重定向标准文件描述符（默认情况下定向到/dev/null） 
 try: 
  pid = os.fork() 
   #父进程(会话组头领进程)退出，这意味着一个非会话组头领进程永远不能重新获得控制终端。 
  if pid > 0: 
   sys.exit(0) #父进程退出 
 except OSError, e: 
  sys.stderr.write ("fork #1 failed: (%d) %s\n" % (e.errno, e.strerror) ) 
  sys.exit(1) 
 
  #从母体环境脱离 
 os.chdir("/") #chdir确认进程不保持任何目录于使用状态，否则不能umount一个文件系统。也可以改变到对于守护程序运行重要的文件所在目录 
 os.umask(0) #调用umask(0)以便拥有对于写的任何东西的完全控制，因为有时不知道继承了什么样的umask。 
 os.setsid() #setsid调用成功后，进程成为新的会话组长和新的进程组长，并与原来的登录会话和进程组脱离。 
 
  #执行第二次fork 
 try: 
  pid = os.fork() 
  if pid > 0: 
   sys.exit(0) #第二个父进程退出 
 except OSError, e: 
  sys.stderr.write ("fork #2 failed: (%d) %s\n" % (e.errno, e.strerror) ) 
  sys.exit(1) 
 
  #进程已经是守护进程了，重定向标准文件描述符 
 
 for f in sys.stdout, sys.stderr: f.flush() 
 si = open(stdin, 'r') 
 so = open(stdout, 'a+') 
 se = open(stderr, 'a+', 0) 
 os.dup2(si.fileno(), sys.stdin.fileno()) #dup2函数原子化关闭和复制文件描述符 
 os.dup2(so.fileno(), sys.stdout.fileno()) 
 os.dup2(se.fileno(), sys.stderr.fileno()) 
 
#示例函数：每秒打印一个数字和时间戳 
def main(): 
 import time 
 sys.stdout.write('Daemon started with pid %d\n' % os.getpid()) 
 sys.stdout.write('Daemon stdout output\n') 
 sys.stderr.write('Daemon stderr output\n') 
 c = 0 
 while True: 
  sys.stdout.write('%d: %s\n' %(c, time.ctime())) 
  sys.stdout.flush() 
  c = c+1 
  time.sleep(1) 
 
if __name__ == "__main__": 
  daemonize('/dev/null','/tmp/daemon_stdout.log','/tmp/daemon_error.log') 
  main() 

#!/usr/bin/env python 
#coding: utf-8 
 
#python模拟linux的守护进程 
 
import sys, os, time, atexit, string 
from signal import SIGTERM 
 
class Daemon: 
 def __init__(self, pidfile, stdin='/dev/null', stdout='/dev/null', stderr='/dev/null'): 
  #需要获取调试信息，改为stdin='/dev/stdin', stdout='/dev/stdout', stderr='/dev/stderr'，以root身份运行。 
 self.stdin = stdin 
 self.stdout = stdout 
 self.stderr = stderr 
 self.pidfile = pidfile 
 
 def _daemonize(self): 
 try: 
  pid = os.fork() #第一次fork，生成子进程，脱离父进程 
  if pid > 0: 
  sys.exit(0)  #退出主进程 
 except OSError, e: 
  sys.stderr.write('fork #1 failed: %d (%s)\n' % (e.errno, e.strerror)) 
  sys.exit(1) 
 
 os.chdir("/")  #修改工作目录 
 os.setsid()  #设置新的会话连接 
 os.umask(0)  #重新设置文件创建权限 
 
 try: 
  pid = os.fork() #第二次fork，禁止进程打开终端 
  if pid > 0: 
  sys.exit(0) 
 except OSError, e: 
  sys.stderr.write('fork #2 failed: %d (%s)\n' % (e.errno, e.strerror)) 
  sys.exit(1) 
 
  #重定向文件描述符 
 sys.stdout.flush() 
 sys.stderr.flush() 
 si = file(self.stdin, 'r') 
 so = file(self.stdout, 'a+') 
 se = file(self.stderr, 'a+', 0) 
 os.dup2(si.fileno(), sys.stdin.fileno()) 
 os.dup2(so.fileno(), sys.stdout.fileno()) 
 os.dup2(se.fileno(), sys.stderr.fileno()) 
 
  #注册退出函数，根据文件pid判断是否存在进程 
 atexit.register(self.delpid) 
 pid = str(os.getpid()) 
 file(self.pidfile,'w+').write('%s\n' % pid) 
 
 def delpid(self): 
 os.remove(self.pidfile) 
 
 def start(self): 
  #检查pid文件是否存在以探测是否存在进程 
 try: 
  pf = file(self.pidfile,'r') 
  pid = int(pf.read().strip()) 
  pf.close() 
 except IOError: 
  pid = None 
 
 if pid: 
  message = 'pidfile %s already exist. Daemon already running!\n' 
  sys.stderr.write(message % self.pidfile) 
  sys.exit(1) 
  
 #启动监控 
 self._daemonize() 
 self._run() 
 
 def stop(self): 
 #从pid文件中获取pid 
 try: 
  pf = file(self.pidfile,'r') 
  pid = int(pf.read().strip()) 
  pf.close() 
 except IOError: 
  pid = None 
 
 if not pid: #重启不报错 
  message = 'pidfile %s does not exist. Daemon not running!\n' 
  sys.stderr.write(message % self.pidfile) 
  return 
 
  #杀进程 
 try: 
  while 1: 
  os.kill(pid, SIGTERM) 
  time.sleep(0.1) 
  #os.system('hadoop-daemon.sh stop datanode') 
  #os.system('hadoop-daemon.sh stop tasktracker') 
  #os.remove(self.pidfile) 
 except OSError, err: 
  err = str(err) 
  if err.find('No such process') > 0: 
  if os.path.exists(self.pidfile): 
   os.remove(self.pidfile) 
  else: 
  print str(err) 
  sys.exit(1) 
 
 def restart(self): 
 self.stop() 
 self.start() 
 
 def _run(self): 
 """ run your fun""" 
 while True: 
  #fp=open('/tmp/result','a+') 
  #fp.write('Hello World\n') 
  sys.stdout.write('%s:hello world\n' % (time.ctime(),)) 
  sys.stdout.flush() 
  time.sleep(2) 
  
 
if __name__ == '__main__': 
 daemon = Daemon('/tmp/watch_process.pid', stdout = '/tmp/watch_stdout.log') 
 if len(sys.argv) == 2: 
  if 'start' == sys.argv[1]: 
   daemon.start() 
  elif 'stop' == sys.argv[1]: 
   daemon.stop() 
  elif 'restart' == sys.argv[1]: 
   daemon.restart() 
  else: 
   print 'unknown command' 
   sys.exit(2) 
  sys.exit(0) 
 else: 
  print 'usage: %s start|stop|restart' % sys.argv[0] 
  sys.exit(2) 

class MyDaemon(Daemon): 
 def run(self): 
  while True: 
   fp=open('/tmp/run.log','a+') 
   fp.write('Hello World\n') 
   time.sleep(1) 

#/bin/sh 
while true 
do 
 count=`ps -ef | grep "daemonclass.py" | grep -v "grep"` 
 if [ "$?" != "0" ]; then 
  daemonclass.py start 
 fi 
 sleep 2 
done 

#!/usr/bin/env python 
#coding: utf-8 
import fcntl, sys, time, os 
pidfile = 0 
 
def ApplicationInstance(): 
 global pidfile 
 pidfile = open(os.path.realpath(__file__), "r") 
 try: 
  fcntl.flock(pidfile, fcntl.LOCK_EX | fcntl.LOCK_NB) #创建一个排他锁,并且所被锁住其他进程不会阻塞 
 except: 
  print "another instance is running..." 
  sys.exit(1) 
 
if __name__ == "__main__": 
 ApplicationInstance() 
 while True: 
  print 'running...' 
  time.sleep(1) 

#!/usr/bin/env python 
#coding: utf-8 
import fcntl, sys, time 
pidfile = 0 
 
def ApplicationInstance(): 
 global pidfile 
 pidfile = open("instance.pid", "w") 
 try: 
  fcntl.lockf(pidfile, fcntl.LOCK_EX | fcntl.LOCK_NB) #创建一个排他锁,并且所被锁住其他进程不会阻塞 
 except IOError: 
  print "another instance is running..." 
  sys.exit(0) 
 
if __name__ == "__main__": 
 ApplicationInstance() 
 while True: 
  print 'running...' 
  time.sleep(1) 

#!/usr/bin/env python 
#coding: utf-8 
import time, os, sys 
import signal 
 
pidfile = '/tmp/process.pid' 
 
def sig_handler(sig, frame): 
 if os.path.exists(pidfile): 
  os.remove(pidfile) 
 sys.exit(0) 
 
def ApplicationInstance(): 
 signal.signal(signal.SIGTERM, sig_handler) 
 signal.signal(signal.SIGINT, sig_handler) 
 signal.signal(signal.SIGQUIT, sig_handler) 
 
 try: 
  pf = file(pidfile, 'r') 
  pid = int(pf.read().strip()) 
  pf.close() 
 except IOError: 
  pid = None 
 
 if pid: 
  sys.stdout.write('instance is running...\n') 
  sys.exit(0) 
 
 file(pidfile, 'w+').write('%s\n' % os.getpid()) 
 
if __name__ == "__main__": 
 ApplicationInstance() 
 while True: 
  print 'running...' 
  time.sleep(1) 

#!/usr/bin/env python 
#coding: utf-8 
import time, commands, signal, sys 
 
def sig_handler(sig, frame): 
 if os.path.exists("/tmp/test"): 
  os.rmdir("/tmp/test") 
 sys.exit(0) 
 
def ApplicationInstance(): 
 signal.signal(signal.SIGTERM, sig_handler) 
 signal.signal(signal.SIGINT, sig_handler) 
 signal.signal(signal.SIGQUIT, sig_handler) 
 if commands.getstatusoutput("mkdir /tmp/test")[0]: 
  print "instance is running..." 
  sys.exit(0) 
 
if __name__ == "__main__": 
 ApplicationInstance() 
 while True: 
  print 'running...' 
  time.sleep(1) 

import os 
import os.path 
import time 
 
 
#class used to handle one application instance mechanism 
class ApplicationInstance: 
 
 #specify the file used to save the application instance pid 
 def __init__( self, pid_file ): 
  self.pid_file = pid_file 
  self.check() 
  self.startApplication() 
 
 #check if the current application is already running 
 def check( self ): 
  #check if the pidfile exists 
  if not os.path.isfile( self.pid_file ): 
   return 
  #read the pid from the file 
  pid = 0 
  try: 
   file = open( self.pid_file, 'rt' ) 
   data = file.read() 
   file.close() 
   pid = int( data ) 
  except: 
   pass 
  #check if the process with specified by pid exists 
  if 0 == pid: 
   return 
 
  try: 
   os.kill( pid, 0 ) #this will raise an exception if the pid is not valid 
  except: 
   return 
 
  #exit the application 
  print "The application is already running..." 
  exit(0) #exit raise an exception so don't put it in a try/except block 
 
 #called when the single instance starts to save it's pid 
 def startApplication( self ): 
  file = open( self.pid_file, 'wt' ) 
  file.write( str( os.getpid() ) ) 
  file.close() 
 
 #called when the single instance exit ( remove pid file ) 
 def exitApplication( self ): 
  try: 
   os.remove( self.pid_file ) 
  except: 
   pass 
 
 
if __name__ == '__main__': 
 #create application instance 
 appInstance = ApplicationInstance( '/tmp/myapp.pid' ) 
 
 #do something here 
 print "Start MyApp" 
 time.sleep(5) #sleep 5 seconds 
 print "End MyApp" 
 
 #remove pid file 
 appInstance.exitApplication() 

#!/usr/bin/env python 
#coding: utf-8 
import socket, time, sys 
 
 
def ApplicationInstance(): 
 try:  
  global s 
  s = socket.socket() 
  host = socket.gethostname() 
  s.bind((host, 60123)) 
 except: 
  print "instance is running..." 
  sys.exit(0) 
 
if __name__ == "__main__": 
 ApplicationInstance() 
 while True: 
  print 'running...' 
  time.sleep(1) 

#!/usr/bin/env python 
#coding: utf-8 
import socket, time, sys 
import functools 
 
#使用装饰器实现 
def ApplicationInstance(func): 
 @functools.wraps(func) 
 def fun(*args,**kwargs): 
  import socket 
  try: 
   global s 
   s = socket.socket() 
   host = socket.gethostname() 
   s.bind((host, 60123)) 
  except: 
   print('already has an instance...') 
   return None 
  return func(*args,**kwargs) 
 return fun 
 
@ApplicationInstance 
def main(): 
 while True: 
  print 'running...' 
  time.sleep(1) 
 
if __name__ == "__main__": 
 main()