如何使用 Python 查看文件而不是目录的更改？

Question

问题：How do I watch a file for changes using Python? suggests using watchdog, but I found it was only able to watch a directory, not a file. watchdog-test.py是watchdog的示例脚本：

$ python watchdog-test.py ab_test_res.sh &
[1] 30628
fbt@fbt64:~/laike9m$ Traceback (most recent call last):
  File "watchdog-test.py", line 15, in <module>
    observer.start()
  File "/usr/local/lib/python2.7/dist-packages/watchdog/observers/api.py", line 255, in start
    emitter.start()
  File "/usr/local/lib/python2.7/dist-packages/watchdog/utils/__init__.py", line 111, in start
    self.on_thread_start()
  File "/usr/local/lib/python2.7/dist-packages/watchdog/observers/inotify.py", line 121, in on_thread_start
    self._inotify = InotifyBuffer(path, self.watch.is_recursive)
  File "/usr/local/lib/python2.7/dist-packages/watchdog/observers/inotify_buffer.py", line 35, in __init__
    self._inotify = Inotify(path, recursive)
  File "/usr/local/lib/python2.7/dist-packages/watchdog/observers/inotify_c.py", line 187, in __init__
    self._add_dir_watch(path, recursive, event_mask)
  File "/usr/local/lib/python2.7/dist-packages/watchdog/observers/inotify_c.py", line 363, in _add_dir_watch
    raise OSError('Path is not a directory')
OSError: Path is not a directory

那么最好的解决方案是什么？我正在使用 Linux(Ubuntu 12.04)。顺便说一句，我不想使用轮询。

Answer 1

您可以通过监视文件所在的目录并仅响应影响您的文件的更改事件来使用看门狗监视文件。像这样的东西会为你做的：

from watchdog.observers import Observer
from watchdog.events import FileSystemEventHandler

class FileModifiedHandler(FileSystemEventHandler):

    def __init__(self, path, file_name, callback):
        self.file_name = file_name
        self.callback = callback

        # set observer to watch for changes in the directory
        self.observer = Observer()
        self.observer.schedule(self, path, recursive=False)
        self.observer.start()
        self.observer.join()

    def on_modified(self, event): 
        # only act on the change that we're looking for
        if not event.is_directory and event.src_path.endswith(self.file_name):
            self.observer.stop() # stop watching
            self.callback() # call callback


from sys import argv, exit

if __name__ == '__main__':

    if not len(argv) == 2:
        print("No file specified")
        exit(1)

    def callback():
        print("FILE WAS MODIFED")

    FileModifiedHandler('.', argv[1], callback)

我只能在 windows 上测试它，但它应该是 os agnostic。

如何使用 Python 查看文件而不是目录的更改？

How do I watch a file, not a directory for changes using Python?

python

file

watch

python-watchdog