1. Grabbing the source

Repo is a tool provided by Google that simplifies using Git in the context of the Android source.

1.1 Installing dependencies and Repo

Several packages are needed in order to build crDroid

sudo apt install bc bison build-essential ccache curl flex g++-multilib gcc-multilib git gnupg gperf imagemagick lib32ncurses5-dev lib32readline-dev lib32z1-dev liblz4-tool libncurses5 libncurses5-dev libsdl1.2-dev libssl-dev libwxgtk3.0-gtk3-dev libxml2 libxml2-utils lzop pngcrush rsync schedtool squashfs-tools xsltproc zip zlib1g-dev 

Install Repo tool

# Make a directory where Repo will be stored and add it to the path
$ mkdir ~/bin
$ PATH=~/bin:$PATH

# Download Repo itself
$ curl https://storage.googleapis.com/git-repo-downloads/repo > ~/bin/repo

# Make Repo executable
$ chmod a+x ~/bin/repo

1.2 Initializing Repo

# Create a directory for the source files
# This can be located anywhere (as long as the fs is case-sensitive)
$ mkdir crDroid
$ cd crDroid

# Install Repo in the created directory
$ repo init -u https://github.com/crdroidandroid-Revived/android.git -b 10.0 --git-lfs

# Or, if you want to save space:
$ repo init --depth=1 -u https://github.com/crdroidandroid-Revived/android.git -b 10.0 --git-lfs

This is what you will run each time you want to pull in upstream changes. Keep in mind that on your first run, it is expected to take a while as it will download all the required Android source files and their change histories.

# Let Repo take care of all the hard work
$ repo sync

# Go to the root of the source tree...
$ cd crDroid
# ...and run to prepare our devices list
$ . build/envsetup.sh
# ... now run
$ brunch "your device codename"