how to create a lock file?

[Xorg]

I want to know how you make a lock file with flock(), I have searched for help but couldn't find it.

Should I use the sleep() function when I add something to a file so that users can't hit the refresh button like 3 times in a second?

Isn't there a risk that the update will be interrupted and the file will be truncated?

I would be very grateful if someone could help me with this, thanks! 🙂

[Plakhotnik]

Be carefull, if you use antiquated filesystems like FAT or its derivates. If you file system support filelock - cool, if not - sucks...

[Xorg]

I run IIS 5.0, windows xp, filesystem NTFS.