Ubuntu desktop environment change (unity --> gnome)

The command for installing gnome desktop in ubuntu is sudoapt-getinstallgnome-session-fallback: before sudoapt-getinstallgnome-panel deletes the unity desktop... run the following command to install gnome desktop in ubuntu 12.04 to change the desktop environment (unity --> gnome): sudo apt-get install gnome-session-fallback: sudo apt-get install gnome-panel before deleting the unity desktop, change the default logon interface of ubuntu to gnome. set the logon interface to gnome classic. the command is as follows: the logon interface of sudo/usr/lib/lightdm-set-defaults-s gnome-classic is set to gnome3. the command is as follows: sudo/usr/lib/lightdm-set-defaults-s gnome-shell uninstall unity: sudo apt-get-y-auto-remove purge unitysudo apt-get-y-auto-remove purge unity-commonsudo apt-get-y-auto-remove purge unity-lens * sudo apt-get-y-auto-remove purge unity-servicessudo apt-get-y-auto-remove purge unity-asset-pool