Set a mask (eg using r.mask) and then just go for it.
If you want to "save" the "clipped" raster, then you will
have to use r.resample. Easy.
Simon Cox
___________________________________________________________
Dr Simon Cox __ \
CSIRO Exploration & Mining ,~' L_|\ Australian
39 Fairway, PO Box 437, ;-' \ Geodynamics
Nedlands, WA 6009 Australia ( \ Cooperative
Phone +61 9 284 8443 + ___ / Research
Fax +61 9 389 1906 L~~' "\__/ Centre
simon@ned.dem.csiro.au W
AGCRC info>> http://www.ned.dem.csiro.au/AGCRC/
___________________________________________________________