I assume the sources of harbour are already downloaded and built in your homedir under the
~/harbour path
Then from terminal type:
cd ~/harbour
fakeroot debian/rules binary
at the end into your home directory will find:
harbour_3.2.0-1_amd64.deb
harbour-dbg_3.2.0-1_amd64.deb
to install on other system , copy the deb file on the destination Ubuntu 20.04 pc then type:
sudo dpkg -i harbour_3.2.0-1_amd64.deb
or the dbg ...give your user password the press enter,
then to be sure all dependencies are installed
, then type:
sudo apt -f install
then verify your Harbour build:
which harbour
harbour -build
Hth