[ Python 文章收集 ] watchdog - 監控文件系統事件的 Python 庫和 shell 工具

Source From Here 
Preface 
watchdog 提供了 Python API 和 shell 工具集來監控文件系統的事件。它包含跨平台的 API，一個 shell 工具可以讓你運行命令來監控目錄的變化。以下是一個使用 watchdog 來監控目錄變化的的簡單程序，當事件發生的時候記錄日誌： 

* Create an instance of the watchdog.observers.Observer thread class.
* Implement a subclass of watchdog.events.FileSystemEventHandler as MyEH (or use the built-in watchdog.events.LoggingEventHandler, which already does).
* Schedule monitoring a few paths with the observer instance attaching the event handler.
* Start the observer thread and wait for it generate events without blocking our main thread.
* If a stop signal being received, stop the observer thread

- wd_t1.py 

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1. #!/usr/bin/env python  
2. import sys, os  
3. import time  
4. import logging  
5. from watchdog.observers import Observer  
6. from watchdog.events import LoggingEventHandler  
7.   
8. class MyEH(LoggingEventHandler):  
9.     r''' Logs all the events captured. '''  
10.     def __init__(self):  
11.         super(MyEH, self).__init__()  
12.   
13.     def on_created(self, event):  
14.         r'''  
15.         We only care about the file being created  
16.         '''  
17.         super(MyEH, self).on_created(event)  
18.         print("This event is captured by {}:\n{}\n".format(self.__class__, event))  
19.   
20.   
21. STOP_SIG = 'STOP'  
22. if __name__ == "__main__":  
23.     logging.basicConfig(level=logging.INFO,  
24.                         format='%(asctime)s - %(message)s',  
25.                         datefmt='%Y-%m-%d %H:%M:%S')  
26.     path = sys.argv[1] if len(sys.argv) > 1 else '.'  
27.     event_handler = MyEH()  
28.     observer = Observer()  
29.     observer.schedule(event_handler, path, recursive=True)  
30.     observer.start()  
31.     try:  
32.         while True:  
33.             time.sleep(1)  
34.             if os.path.isfile(STOP_SIG):  
35.                 print("Receive STOP signal({})...".format(STOP_SIG))  
36.                 os.remove(STOP_SIG)  
37.                 observer.stop()  
38.                 break;  
39.     except KeyboardInterrupt:  
40.         observer.stop()  
41.     observer.join()  

Then you can test it this way: 

# ./wd_t1.py & // Run the program in background by monitoring current working path
[1] 23020
# touch test // Create a new file to trigger event
2017-10-10 13:54:39 - Created file: ./test
This event is captured by :


# touch STOP // Create a stop signal to stop the program
Receive STOP signal(STOP)...
[1]+ Done ./wd_t1.py

watchdog 包含一個實用的腳本，名為 watch demo。使用 watchmedo --help 命令可以查看更多關於這個腳本的信息。 

# which watchmedo
/usr/bin/watchmedo

# watchmedo --help // Check help message

...

以下是一個監控 *.py 和 *.txt 文件的變化，記錄到日誌而忽略其他目錄中文件變化的腳本： 

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1. watchmedo log \  
2.     --patterns="*.py;*.txt" \  
3.     --ignore-directories \  
4.     --recursive \  
5.     .  

可以使用 shell-command 子命令來執行shell命令： 

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1. watchmedo shell-command \  
2.     --patterns="*.py;*.txt" \  
3.     --recursive \  
4.     --command='echo "${watch_src_path}"' \  
5.     .  

Supplement 
* Watchdog document