Fatal server error:Server is already active for display 0

Fedora在启动过程中完全正常，未有任何错误提示。但会转到字符界面的登录提示下，而不是X Window的登录界面。

使用startx命令启动X Window失败，提示如下：

Fatal server error:

Server is already active for display 0

If this server is no longer running, remove /tmp/.X0-lock and start again

排错过程：

1. 检查是否只有一个X server在运行。

The number denotes the display number (in this case 0). This number needs to be unique on the system, so you cannot run two servers on one system with identical display numbers. This message indicates that there is already a server with this number running on the system. 

检查方法：

You can verify this by running 

 ps aux | grep `cat /tmp/.X0-lock`

如果有类似的输出，则表明确实有一个Xserver正在运行

If you see an output like: 

root  2283  0.5  5.1 27796 6536 ?    S  Apr21  59:03 [X]

it indicates that there is indeed an Xserver running under this PID.

解决方法：

 To start a second server on the same system you have to give it a different dislay number. 

If you start your servers using startx you can do：

startx -- :1

to start a server with display number 1. 

2. 没有Xserver在运行时，删除tmp/.X0-lock文件，然后再startx

If you are sure there is no other server running on your system and above ps command indicates that no server with this PID is running, you should remove the file /tmp/.X0-lock by doing (as 'root'): 

rm -rf /tmp/.X0-lock

需要用root权限才能删除，其中-f 表示强制删除。