Build tools are required files to compile the sources provided by Google. This includes various things like java, gcc, gnupg, etc.
sudo apt-get update
sudo apt-get install openjdk-8-jdk
sudo apt-get install git-core gnupg flex bison gperf build-essential zip curl zlib1g-dev gcc-multilib g++-multilib libc6-dev-i386 lib32ncurses5-dev x11proto-core-dev libx11-dev lib32z-dev ccache libgl1-mesa-dev libxml2-utils xsltproc unzip bc imagemagick
git config --global user.name "YOUR USERNAME"
git config --global user.email "youremailid@example.com"
It helps to avoid typing username and password again and again whenever you push something Click here