How to detect change in file

[leuce]

G'day everyone

Can you tell me what is the simplest way to detect if a file has been changed? I just need to detect when a file is changed, so that I can read its contents whenever it changes. It will be the same file all the time, with a known file name, and it's just the one file. The file size will usually be less than 10 kilobytes.

One way I can think of is to check the file's creation date ten times a second (and compare it with the previous check), but if you think this is a good method, can anyone tell me how to check a file's creation date? Another way may be to check the file's size -- not such an accurate method but it is likely that the file changes won't all be the same size. I guess I could even open, read and close the file ten times a second, and hope that the other program that writes to it won't clash with the script, but somehow I don't think that that would be the best way of doing it.

I look forward to your replies.

Samuel (leuce)

[d0n]

well using FileGetTime, you can find the time that the file was last accessed (if the file is changed for sure after its accessed)

[IchBistTod]

you could read the files contents the first time, then see f its the same the second time, and if the file contents are not the same then take action

[leuce]

you could read the files contents the first time, then see f its the same the second time, and if the file contents are not the same then take action

I think you misunderstood me. I don't need to determine whether the file's contents changes or not. It changes. It changes regularly. What I want the script to do is to detect *when* it changes so that action can be taken very shortly after it had changed. During the time that the script runs (a few hours, perhaps), the file will change several hundred times, and I would like to know about the change very, very shortly after it happens (within a 10th of a second, even).

[martin]

The usual way is to check the file's archive attribute. Turn it off at some point. Then if it's changed then the file has changed, assuming you don't need to gaurd against malicious programs. This is how many backup programs decide what has changed since the last backup.

[KaFu]

Take a look at the the MonitorFileActivity UDF / sample in my signature.