you will need internet access for that to work, too
you will have to specify, at the end of the command, either the GNUmed version number you want installed (if not the name of a tarball) e.g. for v0.4.3: ./gm-install_client_locally.sh 0.4.3
GNUmed will be installed into the home directory of this user (below /home/$USER/.gnumed/client-installation/) and can be harmlessly deleted any time you wish to do so
the script will offer trying to install needed dependancies
it will also put a versioned startup link onto the desktop
Manual installation
Assuming you have already installed any dependencies (Linux or Mac OS), obtain the GNUmed client code package: