I was able to set up a text-only UI (CLI) by editing the file /etc/default/grub in Ubuntu 12.04 as per the instructions in:
How do I disable X (GUI) at boot so that the system boots in CLI mode? using these commands:
sudo nano /etc/default/grub
to open the grub file and replaced the line:
GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash”
with
GRUB_CMDLINE_LINUX_DEFAULT=”text”
which sets CLI as default session.
But, how do I revert to X-session (GUI) as the default one? I don't want to log into text mode and 'start' the lightdm every time. So I tried replacing back the GRUB_CMDLINE_LINUX_DEFAULT="text"
to GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
, and did update-grub
too, but something unexpected happened, an unbootable system! (probably the DM got meshed up) How do I fix this?
Best Answer
Found the solution! So I'm posting it here myself...
To revert back to a graphical login and session (X session),
GRUB_CMDLINE_LINUX_DEFAULT="text"
in the /etc/default/grub file should be replaced byGRUB_CMDLINE_LINUX_DEFAULT="quiet splash reboot=bios"
(orGRUB_CMDLINE_LINUX_DEFAULT="quiet splash reboot=api"
for some Dell laptops). After having done this editing, save the file and run theupdate-grub
command, and thenreboot
to see if the graphical login greeter appears. If it does, that's it... you can then log-in...But if you still remain stuck with the problem (like I was..), you can try using gdm as your display-manager (DM) or you could also try reinstalling lightgdm. I uninstalled lightgdm and set gdm as the new manager with the command that follows:
and choose the DM you want so that it is set as the default option.
If your choice of DM was gdm, now you may uninstall lightdm,
sudo apt-get remove lightdm
, andsudo reboot
. And there you are with our old gdm graphical display-manager.But if you choose lightdm which if which crashed earlier like mine did, you'd like to do a reinstall of lightdm instead like described below:
Log-in to a new tty (press Ctrl + Alt + F1) and enter the commands;
and then set lightdm as the default manager and reboot to see it in effect.