Python monitor file contents

Want the power of Periscope or Tableau, without the big monthly bill? Setup Metabase to run locally on your CentOS server. Python Servers and Scaling. Software engineer looking to level up your career? Check out my project SWEPro. There are 2 main classes: Watcher - this waits for any events on the watched directory Handler - this is the event handler that takes action when an event is received import time from watchdog.

I endorse this answer. Only note: the example on their project page doesn't work out of the box. Use the one on their github instead.

We use watchdog. We may switch to QFileSystemWatcher. Just a fair warning- watchdog is good but far from perfect on all platforms at this time. Each OS has it's idiosyncrasies. So, unless you are dedicated to making it perfect you will be pulling your hair out.

If you are just looking to watch 10 files or so, I'd poll. It's mainly for watching huge folder structures IMHO. My one gripe with watchdog is, that it has many dependencies. Fewer than PyQt, of course, but it doesn't work and feel like the minimal, best practice, does-one-job-and-does-it-right solution.

Is denfromufa correct here? Does watchdog really lock files, so they can't be edited concurrently to watchdog watching them? I can hardly believe that, it would be completely useless. Show 6 more comments. To read it: os. Sardathrion - against SE abuse 15k 24 24 gold badges 93 93 silver badges bronze badges.

Deestan Deestan How can you do this on an interval? Great simple solution! I added a check to keep it from reporting the file changed on first run: if self. Otherwise, polling will probably be the only really platform-independent option.

Note: I haven't tried any of these solutions. Horst Gutmann Horst Gutmann 9, 2 2 gold badges 25 25 silver badges 31 31 bronze badges. This answer is Windows-specific, but it appears that some cross-platform solutions to this problem have been posted here as well. It's better to insert the relevant content from cited sources as they can become outdated. I think that this is quite possibly the best answer of the bunch given that they either a rely on Win32's FileSystemwatcher object and cannot be ported or b poll for the file which is bad for performance and will not scale.

It's a pity Python doesn't have this facility built in as PyQt is a huge dependency if all you're using is teh QFileSystemWatcher class. I like this solution. QApplication sys. CadentOrange, if you don't like the pyQt dependency, the watchdog package is the right answer — Mike Pennington. This is no longer supported on PyQt5 — Romain Vincent. Show 3 more comments. Maxime Maxime 1, 1 1 gold badge 26 26 silver badges 38 38 bronze badges.

Works like a charm with Linux kernel 2. Same for me, works for directory only and watch files in this directory. But it won't work for modified files in subdirectories, so it looks like you need to walk throught subdirectories and watch all of them.

Check out pyinotify. Michael Palmer Michael Palmer 2 2 silver badges 2 2 bronze badges. Not to put a damper on this answer, but after reading this article, I would say that it may not be as glamourous a solution as thought. Better to look for other options.. Thanks everyone for your input - great stuff! Jon Cage. Doesn't really scale well to large numbers of files though — 4Oh4. Doesn't this trigger the action every time it's run?

I've used your script to call some function on file change. My function doesn't take any arguments unlike yours. Show 1 more comment. Community Bot 1 1 1 silver badge. You can you sys. You code doesn't work if the file is truncated. Python has builtin function file. I've posted a modified version of your code. You may incorporate it in your answer if it works for you. Updated to support python3 — ronedg. Brilliant, thanks! I replaced the listdir with the newer scandir which is supposedly faster and the result also has convenient stat method for getting the mod time.

Well, since you are using Python, you can just open a file and keep reading lines from it. Here is a simplified version of Kender's code that appears to do the same trick and does not import the entire file: Check file for new data. I had written this earlier when I didn't know much about Win32 APIs or how to use them, but it still functions well, so I'm leaving it here in this post as reference.

To make working with Win32 APIs easier, we need to install pywin32 package which provides most of the primitives and types for Win32 APIs, though it's not a strict dependency. Windows provides a couple of methods for data exchange between applications. Clipboard is one of them. All applications have access to it. But we first need to create a primitive "application" that Windows recognizes. We subscribe it for the clipboard updates. Windows uses window s hah! I've written about how windows and messaging works on Windows in another post where I explored USB hotplugging events, which might be worth reading.

Let's create a window, and set print function as its window procedure :. When we run it doesn't do much except to dump messages sent by Windows to console. We need to register this window as a "clipboard format listener" using AddClipboardFormatListener API, to get notified by Windows whenever the contents of the clipboard change. Now when we run this, it still prints the previous message, but when you copy something to the clipboard it receives another message:.

Now we can build our script around it. One thing we need to watch out for is that because win32gui. So we run it inside a thread, which lets KeyboardInterrupt to bubble up and terminate the script.

When we run it, and copy something text, files and check the console, we can see it prints clipboard updated! Windows clipboard has a concept called "clipboard format". When you copy something, depending on application the payload is also attached a bunch of metadata, allowing it to be used in various contexts.

For example, when you copy a table from a webpage, you have the option to paste it as plain text, or paste it in Excel and have it formatted as a table.