Booting LiveCD Without X

LiveCD environments can usually be helpful for testing, but if you're troubleshooting a problem where X does not start up, that makes it difficult to retrieve the log files and other such things. But it can be done:

0. Boot to the 'Start or Install Ubuntu' prompt. If you can't get to that, then you have problems in something other than X to sort out first. See BootParameters for ideas.

1. From 'Start or Install Ubuntu', try booting with the safe graphics mode option. If that works, you can proceed with debugging normally.

2. If it does not work, see if you can switch to a console by pressing Ctrl+Alt+F1

Disabling gdm

Option 0 - Automatic Login Through gdm

You can set up gdm to automatically log in a user either via System > Administration > Login Window > Security > Enable Automatic Login, or by editing the /etc/gdm/gdm.conf configuration file, and set AutomaticLoginEnable=true and AutomaticLogin=<username>.

Option 1 - Turning off GDM after bootup

Switch to a tty (ctrl+alt+F1) or use ssh, log in, and shut off GDM for the current session like this:

   $ sudo /etc/init.d/gdm stop

Check to see if you have any remaining X sessions running, and if so, kill them:

   $ ps aux | grep /usr/bin/X
   bryce     5379  0.0  0.0   1784   552 pts/35   S+   03:10   0:00 grep /usr/bin/X
   root      7051  1.0  5.0 112224 105556 tty7    Ss+  Jul01 197:49 /usr/bin/X :0 -br -audit 0 -auth /var/lib/gdm/:0.Xauth -nolisten tcp vt7

   $ sudo kill 7051
   $ sudo kill -KILL 7051

or just

   $ sudo pkill Xorg
   $ sudo pkill -KILL Xorg

This option is appropriate if your system boots up okay other than X, such that you can either ssh into it or access a tty. If gdm is completely locking up your system during boot up, then see the next options.

Option 2 - Temporarily disabling GDM

To disable gdm from running during boot, you can either boot with the "text" boot parameter or disable the rc service like this:

   sudo update-rc.d gdm stop 2 3 4 5 .

Please note that there is a dot at the end. This is essential.

Then to re-enable it later,

   sudo update-rc.d gdm start 30 2 3 4 5 . stop 01 0 1 6 .

This option is useful if gdm or X locks up the system during boot, or if you wish to run X in complete isolation from gdm.

Option 3 - Removing GDM entirely

In order to disable X from starting when booting the system, you can simply remove gdm from the init scripts:

• sudo update-rc.d -f gdm remove

and, to enable X again when booting:

• sudo update-rc.d gdm defaults

This option is probably only useful if you know you want to always boot X manually, and want to eliminate graphical booting entirely.

Starting up X manually

Option 1: startx script

From the text console, run

startx

Option 2: Starting X directly

From the text console with no other X running, you can invoke X directly, bypassing all the startup scripts and stuff:

/usr/X11R6/bin/X :0 

If you're running multiple X sessions, use :1, :2 for second, third sessions. (For debugging, it's usually easiest to stick with a single X session invoked from the console.)

X supports a wide variety of other startup flags that can be of value for debugging problems or working around issues. See man xorg for a comprehensive list. Here's a few particularly useful ones: