lightdm无法启动

今天，当我启动Ubuntu时，它没有启动lightdm，显示黑屏。我更改为控制台Ctrl-Alt-F1并尝试lightdm手动启动

sudo start lightdm

它使我进入图形控制台（Ctrl-Alt-F7），并显示相同的黑屏。而且，它看起来像启动了，控制台返回了进程数，

lightdm start/running, process 3616

但是，之后

sudo stop lightdm

我有

stop: unknown instance

然后我开始 gdm

sudo start gdm

并gdm开始正常。因此，中的问题lightdm。

为了解决该问题，我尝试清除lightdm并重新安装它

sudo apt-get purge lightdm
sudo apt-get install lightdm

和

sudo apt-get install --reinstall lightdm

两种方式都没有帮助。

现在，我使用gdm，但是想要恢复lightdm。

谢谢大家的帮助！

PS：我最近没有安装任何其他驱动程序（并且根本没有NVidia卡）。

PPS：一些其他信息

$ sudo start lightdm
lightdm start/running, process 2466
$ dmesg | grep lightdm
[   18.284992] init: lightdm main process (1446) killed by TERM signal
[   57.691273] init: lightdm main process (2466) terminated with status 1

$ sudo start lightdm
lightdm start/running, process 8140
$ sudo cat /var/log/lightdm/lightdm.log 
[+0.00s] DEBUG: Logging to /var/log/lightdm/lightdm.log
[+0.00s] DEBUG: Starting Light Display Manager 1.2.3, UID=0 PID=8140
[+0.00s] DEBUG: Loading configuration from /etc/lightdm/lightdm.conf
[+0.00s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager
[+0.00s] DEBUG: Registered seat module xlocal
[+0.00s] DEBUG: Registered seat module xremote
[+0.00s] DEBUG: Adding default seat
[+0.00s] DEBUG: Starting seat
[+0.00s] DEBUG: Starting new display for automatic login as user stas
[+0.00s] DEBUG: Starting local X display
[+0.00s] DEBUG: Using VT 7
[+0.00s] DEBUG: Activating VT 7
[+0.01s] DEBUG: Logging to /var/log/lightdm/x-0.log
[+0.01s] DEBUG: Writing X server authority to /var/run/lightdm/root/:0
[+0.01s] DEBUG: Launching X Server
[+0.01s] DEBUG: Launching process 8145: /usr/bin/X :0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
[+0.01s] DEBUG: Waiting for ready signal from X server :0
[+0.01s] DEBUG: Acquired bus name org.freedesktop.DisplayManager
[+0.01s] DEBUG: Registering seat with bus path /org/freedesktop/DisplayManager/Seat0
[+0.03s] DEBUG: Process 8145 exited with return value 1
[+0.03s] DEBUG: X server stopped
[+0.03s] DEBUG: Removing X server authority /var/run/lightdm/root/:0
[+0.03s] DEBUG: Releasing VT 7
[+0.03s] DEBUG: Display server stopped
[+0.03s] DEBUG: Stopping display
[+0.03s] DEBUG: Display stopped
[+0.03s] DEBUG: Stopping X local seat, failed to start a display
[+0.03s] DEBUG: Stopping seat
[+0.03s] DEBUG: Seat stopped
[+0.03s] DEBUG: Required seat has stopped
[+0.03s] DEBUG: Stopping display manager
[+0.03s] DEBUG: Display manager stopped
[+0.03s] DEBUG: Stopping daemon
[+0.03s] DEBUG: Exiting with return value 1

$ sudo cat x-0.log
X: cannot stat /etc/X11/X (No such file or directory), aborting.

尝试按CTRL+ ALT+ F1然后：

sudo /etc/init.d/gdm stop (for Gnome)

sudo /etc/init.d/lightdm stop (for Unity)

sudo dpkg-reconfigure xserver-xorg

如果您希望备份X，请不要担心：

sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf.backup

在所有这些开始X显示之后：

sudo /etc/init.d/gdm start (for Gnome)

sudo /etc/init.d/lightdm start (for Unity)