Unity

How can I reset the Window Manager from CLI?

Asked by donls

Running Ubuntu 12.10 64 bit as VM under VMWare Fusion 5.02, MacBook Pro with Core i5 cpu

I don't like Unity, so I was trying to get other Window Managers running. [After I got Gnome installed, had some trouble switching choice of WM at login, but figured it out (enter password, selct WM from Gear menu, hit enter or right arrow by password - could probably enter password after selecting WM as well. Password entry field is almost below bottom of window when Gear menu is opened.]

I turned off auto-login. After selecting one of the WM choices above Unity (Ubuntu), everything worked as expected. However, when I selected one of those below Unity, the system seems to attempt an auto login, and does not finish. All I can see is the wallpaper, with no menus or icons. I can log in from a terminal session. After I reboot (either from terminal session or from VMWare [Virtual Machine: Restart/Shutdown], the same session starts again, going straight to the window with nothing but wallpaper visible.

Since the VM was a duplicate of my original installation, I duplicated it again, and turned on AutoProtect; I also took a snapshot of the current session. When I selected one of the other WMs, I was able to revert the snapshot and recover control.

On the original problem system, I was able to run startx from the CLI and enter the 'pgrep -l' command from http://askubuntu.com/questions/72549/determine-what-window-manager-or-desktop-is-running which showed me that compiz had started (but I still had no control).

I was also able to init 1 the system and get it into single user mode, but could not get any settings to stick. (later attempts, have not been able to get login prompt with init 1)

I would like to be able to correct this situation by adjusting config files if possible, since I foresee that this could happen at a client site or in other situations where I don't have the Snapshot feature.

So, what file(s) control(s) which WM is selected, and what values can be changed to choose a different WM (one that I can have control over)?

Further progress: After 'init 1', at the single-user prompt, I tried 'init 2' and got the login prompt. Was able to select 'Ubuntu', which starts up in Unity mode again.

So, what could I do with tweaking files that would have produced the same result?

Yet further progress: From Unity mode, I logged out, and was again presented with no login prompt. I restarted the VM, and have the same result as before (no login prompt). From Virtual Terminal, I do 'init 1' followed by 'init 2' and get a login prompt. Note that the login prompt looks quite different from the one I get with a normal startup.

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nolan.bloor (nolan-bloor) said : 		#1

running the command "gnome-panel" will bring up the ui from there.

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donls (don-ellis) said : 		#2

I'm not sure how this can help; could I have some more details, please?

Once I run gnome-panel (if successful), what do I select to correct the problem? I don't see any kind of administration features to select a different WM or reset the WM selection.

The gnome-panel app requires X11, so it won't run from a Virtual Terminal. I just tried it from Terminal.app, and it worked, but that was with a working GUI on the VM (which I have rebuilt and saved snapshots, so I can restore it to the state before another crash - I also have put the really interesting bits in shared locations so I can get to them if I lose the VM again.)

I found some instabilities and deficiencies with VMWare, so I'm running the VM under VirtualBox now. Seems to have fewer hangups, and I've been able to recover when I get a badly-formed WM session.

Again, what I'd really like to have is a solution that I could use from a purely CLI situation (X11 doesn't run or isn't usable). Just some kind of file somewhere that I could edit or delete so the login panel doesn't make assumptions and lets me do the initial selection. In VB, the login window seems to always come up; in VMWare, the login process would skip the panel and go straight to a broken GUI session (with access to Virtual Terminal, allowing me to init 1 and then init 2 (I wonder if just going straight to init 2 would work as well?).

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Launchpad Janitor (janitor) said : 		#3

This question was expired because it remained in the 'Open' state without activity for the last 15 days.

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donls (don-ellis) said : 		#4

Solution found:
[This applies to both VMWare Fusion and VirtualBox]
The problem relates to having 3D Graphics Acceleration turned on. Turning off this feature corrected the problem. Default setting in VMWare is to have it turned on, and I think this is also the case in VirtualBox.