Set up your environment by referring to LineageOS Wiki (mainly "Install the build packages" and "Install the repo command").
Create a new working directory for your LineageOS build and navigate to it:
mkdir ~/git/lineage-20-build-td; cd ~/git/lineage-20-build-td
Initialize your LineageOS workspace:
repo init -u https://github.com/LineageOS/android.git -b lineage-20.0
Clone both this and the patches repos:
git clone https://github.com/rumplestilzken/lineage_build_unified lineage_build_unified -b lineage-20-td
git clone https://github.com/rumplestilzken/lineage_patches_unified lineage_patches_unified -b lineage-20-td
cd ~/git/lineage-20-build-td; git lfs install
Finally, start the build script - for example, to build for all supported archs:
bash lineage_build_unified/buildbot_unified.sh treble gargoyle gargoyleG
Be sure to update the cloned repos from time to time!
Note: VNDKLite targets are generated from built images instead of source-built - refer to sas-creator.
This script is also used to make device-specific and/or personal builds. To do so, understand the script, and try the device and personal keywords.