How to get info on process

[Dan Track]

Hi

I've got a file /opt/development/index.html that I serve. The problem
I'm having is that some other process is touching/locking this file at
random intervals. Now this mystery process seems to only last for less
than a second. So my dilemma is how do I capture what it is given the
short space of time the process acts upon the file. What tools are
available.

I've tried to use

watch lsof /opt/development/index.html

with an interval of 1 sec refresh, but I still can't see the process. Any ideas?

Thanks in advance
Dan