How to disable a src.conf on command-line

[Darren Pilgrim]

M. Warner Losh wrote:
> So if you make WITH_SSP off by default, then having WITH_SSP in the
> src.conf can't be overridden.  If you have it on by default, having
> WITHOUT_SSP in the src.conf file can't be overriden.  this appears to
> be an unintended flaw with the with/without stuff.  I'm not sure the
> right way to compensate.

I can't speak for the "right" way, but if you specify the variable in
src.conf/make.conf with ?= instead of =, you can override it on the
command-line:

# grep KERNCONF /etc/make.conf
KERNCONF?=TTPWEB
# make -V KERNCONF
TTPWEB
# env KERNCONF=SOMETHING_ELSE make -V KERNCONF
SOMETHING_ELSE

-- 
Darren Pilgrim