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. Obtain a Live CD for the release you're testing: http://cdimage.ubuntu.com/releases/
1. At the CD boot menu, add "text" to the boot options: https://help.ubuntu.com/community/BootParameters
2. The CD will now boot but not start X.
3. You can grab xrandr data without starting an X session like this:
xinit -e 'sh -c "xrandr --verbose > xrandr.txt" '
This will try to start X and log some information about the active screen resolution to the file xrandr.log before it stops X again.
4. Start up an X session like this:
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
$ 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
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:
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:
Allow the server to start up even if the mouse device can't be opened or initialised.
Bypasses server's ABI version check when loading e.g. binary drivers (-fglrx/-nvidia). This option should be used with care.
Prevent the server from detaching its initial controlling terminal. This option is only useful when debugging the server. Not all platforms support (or can use) this option.
For each driver module installed, print out the list of options and their argument types.