Ubuntu 12.04 changed itself to xubuntu and stopped working

[Petter Adsen]

On Fri, 31 Jul 2015 01:22:44 +0800
Bret Busby <bret.busby at gmail.com> wrote:

> On 31/07/2015, Colin Law <clanlaw at gmail.com> wrote:
> > On 30 July 2015 at 16:37, Bret Busby <bret.busby at gmail.com> wrote:
> >> On 30/07/2015, Colin Law <clanlaw at gmail.com> wrote:
> >>> On 30 July 2015 at 11:11, Bret Busby <bret.busby at gmail.com> wrote:
> >>>> Hello.
> >>>>
> >>>> I have an Acer V3-772G laptop computer, which has an Intel i-7 4702MQ
> >>>> Haskell CPU/graphics controller and an nVidia GEForce GT-750M graphics
> >>>> thing.
> >>>>
> >>>> I have on the system, Debian 7, Debian 6, Ubuntu 14.04, and, what was
> >>>> Ubuntu 12.04, installed.
> >>>>
> >>>> After two yars of trying to get the computer working, I have found
> >>>> that, of those operating systems, only the two Ubuntu systems have the
> >>>> necessary drivers.
> >>>>
> >>>> To get the interrface that I wanted, I installed the mate desktop
> >>>> environment, along with a number of other desktop environments, and
> >>>> have been using the mate desktop environment as the preferred desktop
> >>>> environment, on both of the Ubuntu installations.
> >>>>
> >>>> In the last week, the Ubuntu 12.04 installation changed the boot
> >>>> splashscreen, to a blue one, and, after the blue splashscreen, the
> >>>> screens (I use an external monitor) go blank, and nothing else is
> >>>> displayed auntil I do a crash/reboot, using the power switch (holding
> >>>> it down until the system stops breathing).
> >>>>
> >>>> I have found that the blue screen displays "xubuntu", and in searching
> >>>> for that, I have found that xubuntu is an xfce version of Ubuntu.
> >>>>
> >>>> I had not wittingly switched the system from being Ubuntu, to xubuntu.
> >>>>
> >>>> In using the recovery mode booting, and getting to a root shell
> >>>> prompt, I tried to use apt-get remove xfce, in the hope that that
> >>>> would get rid of the switch from Ubuntu to xubuntu, and it reurned
> >>>> "xfce not found".
> >>>
> >>> Did you have autologin enabled?  If so then first try disabling it so
> >>> that it should take you to a login screen where you can choose which
> >>> ui to use.
> >>
> >> That is how it was set up, before it changed itself to xubuntu, and,
> >> after I had logged in to the mate desktop environment, it had
> >> defaulted to that login - the environment was still selectable, but,
> >> unless I changed it at the login screen, it defaulted to the mate
> >> desktop environment.
> >>
> >> I do not remember exactly what had happend the last time that I have
> >> logged in to it - I have been uding Ubuntu 14.04, for a while (a week
> >> or so, or a couple of weeks) now, but, it may have been that I tried
> >> the xfce desktop when I logged in, and it decided "stuff this, get rid
> >> of ubuntu, and switch to ubuntu".
> >
> > So have you tried disabling auto login as I suggested?  If it is
> > enabled that is.
> >
> 
> Okay; this is the answer.
> 
> 1. At the top of the Recovery mode menu, is
> 
> "Recovery menu filesystem state readonly"
> 
>  or something like that.
> 
> 2.
> 
> The file lightdm.con, in the specified path, exists.
> 
> Using
> vi /etc/lightdm/lightdm.conf
> I get
> 
> [SeatDefaults]
> greeter-session=unity-greeter
> user-session=ubuntu
> display-setup-script=/sbin/prime-offload
> display-stopped-script=/sbin/prime-switch
> ~
> ~
> ...
> "etc/lightdm/lightdm.conf" [readonly] 5L, 148C 1.1 All
> 
> So it appears that, even if the autologin line was there, I would not
> be able to do anything to change it.

See the answer that Nick gave you below for how to remount your root
filesystem in rw mode. Then you will be able to alter files normally.

When you attempt to boot normally and the screen goes blank, are you
able to switch to a virtual console? Have you got the option of trying
to access the system via the network to see if the rest of the system
is alive and only the console or X is dead?

An idea of exactly what has hung would be very helpful to know where to
go from here.

Petter

-- 
"I'm ionized"
"Are you sure?"
"I'm positive."
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