To Porter:
I just realized that I also have to lock the file while reading as well to prevent write while reading...Thanks

To Smiling Dragon:
Thanks a lot for the pointer...I tried the sample program and thats exactly what I was looking for

Btw, where is the information that the file is locked stored ? How does another process (still using flock) know that a file is locked and has to sleep till unlocked ?

Thanks in advance.
J.