Removing outdated files

[Anon]

Hi,

I'm trying to do a relatively simple thing, but running into problems with date arithmetic and file matching.

I want to delete temporary files older than say 15 minutes, which have a certain prefix (eg. "qf").

Do filemtime and time functions return time in the same units (so I can subtract filemtime from time to get elapsed time)? I seem to be having problems with this (on UNIX).

How do I match the candidate files (I'm not good at regular expressions if this is what is required).

Any examples much appreciated.

Thanks,
Mark