[lug] Determine mtime

[John Starkey]

I have a php script that creates a zone file and I need to restart named 
  after it's created. The best that I can come up with is to check mtime 
on the new zone file every 15 minutes or so and if it's after the mtime 
of a file I touched when I did the last restart, then restart named 
again. Does anyone know of a way to determine the mtime of a file using 
bash, or know of a more efficient way to do this?

TIA,

John