|One of the best features of the make process is the fetch process.
If the files it needs cannot be found, make will go and fetch the file for you. It
searches a list of file locations and uses the first location which succeeds.
examine /usr/share/mk/bsd.port.mk, you'll find that it modifies the URL search
path and adds file:/crdom/ports/distfiles. This tells the make process
to search your CDROM. If the device is not mounted, the fetch will fail and the
search process continues with the next location in the list.
It is because of this search process that the following should be enough to build your
# #installer usually leaves /cdrom in fstab
# #which means you don't have to do much to mount it
# mount /cdrom
# cd /usr/ports/foo/bar
# make install