detecting file changes

[Anonymous Monk]

OK...here is my dilema. I have a file that is constantly being appended too from another script using a while loop. I'm trying to ficure out an easy way to detect any changes in the files contents. I've thought about monitoring the file timestamp change but it only gets updated after the script writing to the file terminates. I've also tried reading the contents, sleeping a second, reading it again and I'm able to determine the delta. This work but I was wondering if there is a more elegant solution. Thanks

[Albannach]

Ah, if it's for Windows, then Win32::ChangeNotify should be the answer.

[graff]

You don't mention what OS you're using, and I don't actually know if this is an OS-dependent issue, but I do know that on any unix-like system, the file size reported by "-s" will reflect the recent growth of a file while it is actively being written to by some other process:

my $path = "dir/file_to_watch";
my $prev_size = -s $path;
while (1) {
    sleep 5;
    my $size_now = -s $path;
    if ( $size_now > $prev_size ){
        print "file grew as of ".scalar localtime().$/;
        $prev_size = $size_now;
    }
}

[Anonymous Monk]

I should have mentioned that this is for Win32

[blazar]

I think you may be after the content of perldoc -q tail, which explictly also points to File::Tail, a module you may be interested in.

[rafl]

Linux::Inotify2 might be handy as well.

Cheers, Flo