Linux: Adding a GUI to headless/server installs

Server and minimal installs are normally headless and have no graphical interface.

If needed you can add a GUI manually. The process is slightly different depending on the distro.

RedHat / CentOS 7.x

# yum update
# yum groupinstall "Server with GUI"

RedHat / CentOS 8.x

# dnf update
# dnf groupinstall workstation

Ubuntu 18.04.x LTS

# apt update

[Install minimum GNOME desktop]
# apt install --no-install-recommends ubuntu-desktop

[Install full desktop with associated applications]
(Long process and too many extras installed)

# apt install ubuntu-desktop

[There are other alternative desktops and installations possible:]

[Generic Gnome desktop]
# apt install vanilla-gnome-desktop

[Mate]
# apt install ubuntu-mate-desktop

[Xfce]
# apt install xubuntu-desktop

[KDE]
# apt install kubuntu-desktop

[LightDM]
# apt install --no-install-recommends lightdm

Debian 9.x

# apt update
# apt install gnome-core

Debian 10.x

# apt update
# apt install gnome-core

All the above distros use systemd as their init system and you set the default run level with the same set of commands.

[Enable run level 5 by default]
systemctl  set-default graphical.target

[Enable run level 3 by default]
systemctl  set-default multi-user.target

Despite systemd you can still use init to start the graphical interface without having to reboot.

# init 5