Debian 9: Install MATE for desktop environment

The following command will install MATE.

$ sudo apt install -y expect
cat <<EOF | expect
set timeout -1
spawn sudo apt install -y task-mate-desktop
expect "Default display manager: "
send "lightdm\n"
expect eof
EOF
$ sudo reboot

You can select other desktop environment.

MATE is displayed.

The following command will uninstall MATE.

$ sudo apt remove -y task-mate-desktop mate-* libmate*
$ sudo apt autoremove -y
$ sudo apt install --reinstall -y gdm3
$ sudo reboot