Python中用MacFSEvents模块监视MacOS文件系统改变一例

最近一个项目中用gulp-watch不能满足需求，于是想到了用Python来解决问题。在安装了MacFSEvents模块后，写了下面一个小程序。

#!/usr/bin/env python2
#-*- coding: utf-8 -*-

import os,sys,signal                    
from   fsevents import Observer
from   fsevents import Stream  

def callback(FileEvent):
    # attributes of FileEvent：mask, cookie and name.
    # mask: 512-delete;256-create;2-changed
    if FileEvent.name.endswith("index.html") and FileEvent.mask == 256:
        print "site rebuild. redeploy extra assets"
        os.system("gulp")
    elif FileEvent.name.endswith(".scss") and FileEvent.mask == 2:
        print "scss changed! compile and redeploy extra assets"
        os.system("gulp sass")

if __name__ == '__main__':
    observer  = Observer()
    stream    = Stream(callback, ".", file_events=True)
    observer.schedule(stream)
    observer.start()  
    #按Control+\强制结束
 

    但是运行时发现只能用Control+\强杀进程，而不能用Control+C结束。

    经google搜索及自行研究结果，得到下面这段程序。用fork子进程的方法，使得进程响应Control+C 退出。

 1 #!/usr/bin/env python2
 2 #-*- coding: utf-8 -*-
 3 
 4 import os,sys,signal                    
 5 from   fsevents import Observer
 6 from   fsevents import Stream  
 7 
 8 def callback(FileEvent):
 9     # attributes of FileEvent：mask, cookie and name.
10     # mask: 512-delete;256-create;2-changed;...
11     if FileEvent.name.endswith("index.html") and FileEvent.mask == 256:
12         print "site rebuild. redeploy extra assets"
13         os.system("gulp")
14     elif FileEvent.name.endswith(".scss") and FileEvent.mask == 2:
15         print "scss changed! compile and redeploy extra assets"
16         os.system("gulp sass")
17 
18 def child():
19     observer  = Observer()
20     stream    = Stream(callback, ".", file_events=True)
21     observer.schedule(stream)
22     observer.start()
23 
24 class Watcher:  
25     """ 
26　　　　　　创建一个做苦工的子进程。然后父进程等待KeyboardInterrupt并杀掉子进程。
27 
28     """  
29   
30     def __init__(self):  
31         self.child = os.fork()  
32         if self.child == 0:  
33             child()  
34         else:  
35             self.watch()  
36   
37     def watch(self):  
38         try:  
39             os.wait()  
40         except KeyboardInterrupt:  
41             #捕获 Control+C，杀掉子进程 
42             print 'KEYBOARDINTERRUPT\n'  
43             self.kill()  
44         sys.exit()  
45   
46     def kill(self):  
47         try:  
48             os.kill(self.child, signal.SIGKILL)  
49         except OSError: pass  
50   
51 
52 if __name__ == '__main__':
53     Watcher()