How to determine if a Directory/Folder has been changed

Question

I have a folder with the following structure

Parent/
    Child1/
        GrandChild1/
             File1.txt

I need to query Parent folder and find out if Child1 has changed.

Changed = A new file was add/update/deleted.

The Child1 folder DateModified is not updated. Only the GrandChild1 date modified was updated when changes occurs. I am trying to avoid going to the file level to determine if the rootparent has changed. since there will be many folders and sub folder. I just need to know if Child1 has changed.

I do not want to use FileSystemWatcher, since I am running this as a scheduled job and not watching it LIVE.

score 6 · Accepted Answer · edited May 23 '17 at 12:12

6

User FileSystemWatcher. Remember to enable raising events since it is a common mistake (watchfolder.EnableRaisingEvents = true;).

The FileSystemWatcher may prove not to be optimal from a performance perspective. If that is an issue for you, you might implement a CRC check with a Timer to check for changes of the files and folders you are interested in.

Essentially, what I would do is to generate a CRC32 hash for the entire folder I am watching (and save it away into variable A) and when I decide it is time to check for changes, you simply calculate a new CRC32 hash for the same folder (into variable B). You then compare A with B and if they don´t match, something has changed. Really not that difficult.

Reference:

edited May 23 '17 at 12:12

Community

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answered Oct 11 '12 at 14:05

Marcus

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Certainly the simplest solution. But FileSystemWatcher can have [some](http://stackoverflow.com/questions/239988/filesystemwatcher-vs-polling-to-watch-for-file-changes) reliability issues. – hometoast Oct 11 '12 at 14:08
I have used it a couple of times before and never had any problems. Can you elaborate? – Marcus Oct 11 '12 at 14:09
I am runnng a schedule job and cannot use the FileSystemWatcher. Since I am not running live. – Arcadian Oct 11 '12 at 14:13
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Ok, see my edit. Consider implementing a CRC solution to check for changes! – Marcus Oct 11 '12 at 14:15
@Marcus, it's no longer relavant to the OP's question, but this question addresses some of the issues devs have had with it: http://stackoverflow.com/questions/239988/filesystemwatcher-vs-polling-to-watch-for-file-changes – hometoast Oct 11 '12 at 16:37

score 1 · Answer 2 · answered Oct 11 '12 at 14:06

1

Have you tried the file system watcher? You can monitor local drives for changes from a given path, and then if necessary, ignore or process the fact they changed.

answered Oct 11 '12 at 14:06

BugFinder

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jay_t55 · Answer 3 · 2012-10-11T14:31:33.670

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You can use the FileSystemWatcher Class for this.

Alternatively, if you would rather schedule a Task to run, Weekly, for example, you might want to have a look at: http://taskscheduler.codeplex.com/ and http://www.emoreau.com/Entries/Articles/2004/08/Interfacing-the-Windows-Task-Scheduler.aspx

And here's a link to the Windows Task Schedular API

edited Oct 11 '12 at 14:31

answered Oct 11 '12 at 14:08

jay_t55

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Is there a way without having to watch it? I want to run this check once a week and not to have it monitored – Arcadian Oct 11 '12 at 14:24
You could programmatically schedule a Windows Task from within your application, that Watches a directory, or sub-directory at a given date and time (or, Weekly). See my answer for further details. – jay_t55 Oct 11 '12 at 14:30

How to determine if a Directory/Folder has been changed

3 Answers3