我有一个日志文件正在写的另一个进程,我想观察变化。每次发生更改时,我都希望将新数据读入并对其进行一些处理。

最好的方法是什么?我希望在PyWin32库中有某种钩子。我找到了win32文件。函数FindNextChangeNotification,但不知道如何要求它监视特定的文件。

如果有人做过类似的事情,我真的很感激能听到…

[编辑]我应该提到我追求的是一种不需要轮询的解决方案。

[编辑]诅咒!这似乎不能在映射的网络驱动器上工作。我猜windows不会像在本地磁盘上那样“听到”任何对文件的更新。


当前回答

最简单的解决方案是在间隔之后获取同一个文件的两个实例并进行比较。你可以试试这样的东西

    while True:
        # Capturing the two instances models.py after certain interval of time
        print("Looking for changes in " + app_name.capitalize() + " models.py\nPress 'CTRL + C' to stop the program")
        with open(app_name.capitalize() + '/filename', 'r+') as app_models_file:
            filename_content = app_models_file.read()
        time.sleep(5)
        with open(app_name.capitalize() + '/filename', 'r+') as app_models_file_1:
            filename_content_1 = app_models_file_1.read()
        # Comparing models.py after certain interval of time
        if filename_content == filename_content_1:
            pass
        else:
            print("You made a change in " + app_name.capitalize() + " filename.\n")
            cmd = str(input("Do something with the file?(y/n):"))
            if cmd == 'y':
                # Do Something
            elif cmd == 'n':
                # pass or do something
            else:
                print("Invalid input")

其他回答

ACTIONS = {
  1 : "Created",
  2 : "Deleted",
  3 : "Updated",
  4 : "Renamed from something",
  5 : "Renamed to something"
}
FILE_LIST_DIRECTORY = 0x0001

class myThread (threading.Thread):
    def __init__(self, threadID, fileName, directory, origin):
        threading.Thread.__init__(self)
        self.threadID = threadID
        self.fileName = fileName
        self.daemon = True
        self.dir = directory
        self.originalFile = origin
    def run(self):
        startMonitor(self.fileName, self.dir, self.originalFile)

def startMonitor(fileMonitoring,dirPath,originalFile):
    hDir = win32file.CreateFile (
        dirPath,
        FILE_LIST_DIRECTORY,
        win32con.FILE_SHARE_READ | win32con.FILE_SHARE_WRITE,
        None,
        win32con.OPEN_EXISTING,
        win32con.FILE_FLAG_BACKUP_SEMANTICS,
        None
    )
    # Wait for new data and call ProcessNewData for each new chunk that's
    # written
    while 1:
        # Wait for a change to occur
        results = win32file.ReadDirectoryChangesW (
            hDir,
            1024,
            False,
            win32con.FILE_NOTIFY_CHANGE_LAST_WRITE,
            None,
            None
        )
        # For each change, check to see if it's updating the file we're
        # interested in
        for action, file_M in results:
            full_filename = os.path.join (dirPath, file_M)
            #print file, ACTIONS.get (action, "Unknown")
            if len(full_filename) == len(fileMonitoring) and action == 3:
                #copy to main file
                ...

因为没有人提到它,所以我要把它放在那里:在标准库中有一个名为filecmp的Python模块,它有这个cmp()函数来比较两个文件。

只是要确保你没有使用from filecmp import cmp来掩盖Python 2.x中内置的cmp()函数。这在Python 3中是可以的。X,因为不再有这样的内置cmp()函数了。

不管怎样,它的用法是这样的:

import filecmp
filecmp.cmp(path_to_file_1, path_to_file_2, shallow=True)

参数shallow默认为True。如果参数的值为True,则只比较文件的元数据;但是,如果参数的值为False,则比较文件的内容。

也许这个信息对某人有用。

import inotify.adapters
from datetime import datetime


LOG_FILE='/var/log/mysql/server_audit.log'


def main():
    start_time = datetime.now()
    while True:
        i = inotify.adapters.Inotify()
        i.add_watch(LOG_FILE)
        for event in i.event_gen(yield_nones=False):
            break
        del i

        with open(LOG_FILE, 'r') as f:
            for line in f:
                entry = line.split(',')
                entry_time = datetime.strptime(entry[0],
                                               '%Y%m%d %H:%M:%S')
                if entry_time > start_time:
                    start_time = entry_time
                    print(entry)


if __name__ == '__main__':
    main()

相关@4Oh4解决方案一个流畅的更改文件列表观看;

import os
import sys
import time

class Watcher(object):
    running = True
    refresh_delay_secs = 1

    # Constructor
    def __init__(self, watch_files, call_func_on_change=None, *args, **kwargs):
        self._cached_stamp = 0
        self._cached_stamp_files = {}
        self.filenames = watch_files
        self.call_func_on_change = call_func_on_change
        self.args = args
        self.kwargs = kwargs

    # Look for changes
    def look(self):
        for file in self.filenames:
            stamp = os.stat(file).st_mtime
            if not file in self._cached_stamp_files:
                self._cached_stamp_files[file] = 0
            if stamp != self._cached_stamp_files[file]:
                self._cached_stamp_files[file] = stamp
                # File has changed, so do something...
                file_to_read = open(file, 'r')
                value = file_to_read.read()
                print("value from file", value)
                file_to_read.seek(0)
                if self.call_func_on_change is not None:
                    self.call_func_on_change(*self.args, **self.kwargs)

    # Keep watching in a loop
    def watch(self):
        while self.running:
            try:
                # Look for changes
                time.sleep(self.refresh_delay_secs)
                self.look()
            except KeyboardInterrupt:
                print('\nDone')
                break
            except FileNotFoundError:
                # Action on file not found
                pass
            except Exception as e:
                print(e)
                print('Unhandled error: %s' % sys.exc_info()[0])

# Call this function each time a change happens
def custom_action(text):
    print(text)
    # pass

watch_files = ['/Users/mexekanez/my_file.txt', '/Users/mexekanez/my_file1.txt']

# watcher = Watcher(watch_file)  # simple



if __name__ == "__main__":
    watcher = Watcher(watch_files, custom_action, text='yes, changed')  # also call custom action function
    watcher.watch()  # start the watch going

在对蒂姆·戈尔登的剧本进行了一些修改后,我有了以下似乎工作得相当不错的内容:

import os

import win32file
import win32con

path_to_watch = "." # look at the current directory
file_to_watch = "test.txt" # look for changes to a file called test.txt

def ProcessNewData( newData ):
    print "Text added: %s"%newData

# Set up the bits we'll need for output
ACTIONS = {
  1 : "Created",
  2 : "Deleted",
  3 : "Updated",
  4 : "Renamed from something",
  5 : "Renamed to something"
}
FILE_LIST_DIRECTORY = 0x0001
hDir = win32file.CreateFile (
  path_to_watch,
  FILE_LIST_DIRECTORY,
  win32con.FILE_SHARE_READ | win32con.FILE_SHARE_WRITE,
  None,
  win32con.OPEN_EXISTING,
  win32con.FILE_FLAG_BACKUP_SEMANTICS,
  None
)

# Open the file we're interested in
a = open(file_to_watch, "r")

# Throw away any exising log data
a.read()

# Wait for new data and call ProcessNewData for each new chunk that's written
while 1:
  # Wait for a change to occur
  results = win32file.ReadDirectoryChangesW (
    hDir,
    1024,
    False,
    win32con.FILE_NOTIFY_CHANGE_LAST_WRITE,
    None,
    None
  )

  # For each change, check to see if it's updating the file we're interested in
  for action, file in results:
    full_filename = os.path.join (path_to_watch, file)
    #print file, ACTIONS.get (action, "Unknown")
    if file == file_to_watch:
        newText = a.read()
        if newText != "":
            ProcessNewData( newText )

它可能需要进行更多的错误检查,但对于简单地观察日志文件并在将其输出到屏幕之前对其进行一些处理,这样做效果很好。

谢谢大家的投入-很棒的东西!