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How to monitor changes in file content?

Hi,

I need to write a simple(?) component that will monitor the changes being made to a text file and notify them to registered listeners.

I have a process which writes data to a text file in the following way:

Start
... //data
End
Start
...//data
End
...
etc

I want to monitor the file and get notified when certain lines are written (e.g. Start/End).

A quick google search yielded the FileSystemWatcher class but I don't think it fits since it only monitors file system events and not file content, but I could be wrong as I'm fairly new to C#/.NET.

Thanks for any help.

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Colemss

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ajny

ASKER

Hi Colemss,

Thanks for your quick reply!

I was hoping there's a better solution.

As I wrote, I'm already aware of the FileSystemWatcher class and its usages.
What I'm trying to write is a generic file watcher that can detect an arbitrary pattern (regex) being written to a file.

Using FileSystemWatcher will force me to re-read the file every time or (more likely) to keep track of where I stopped the last time and seek to that location before the next search.
Although these approaches will work, I was hoping there's a way to hook the monitor on the write operation (in a sense like a filter), so it can "see" what's about to be written to the file.

Colemss

The only way I can imagine doing this would be with some sort of system hook. It would require win32 dll hooks. Most likely you will find c++ examples. These would be undocumented Microsoft core hooks. Unless this is a major deal its probably not worth doing. I have never seen any examples of looking at the data before or during a file write. It would be interesting.

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monarch_ilhan

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Colemss

That is the full source to my first suggestion. I would try it. But it is using FileSystemWatcher.

monarch_ilhan

He has to use a timer or a filesystemwatcher to monitor changes. I believe a filesystemwatcher will have a better performance.

ajny

ASKER

Thanks for your help, guys.

I'll wait a little while to see if someone can come up with a better solution before I resort to FileSystemWatcher.