#be at your directory contining the source codes
#then run the following commands to build the latest and greatest ardupilot.
#it will delete any old builds if you have them.
# slightly edited from Peter Barker

git fetch origin --tags
git checkout master
git submodule update --recursive
rm -rf build
./waf configure --board blue
./waf copter

#to build latest beta instead
#from Peter Barker

git fetch origin --tags
git checkout ArduCopter-beta
git submodule update --recursive
rm -rf build
./waf configure --board blue
./waf copter