When I enter startx at the Linux GUI terminal, what am I doing?

Look at the following three posts, unidentified,,,

"Login exception Resolution" Ubuntu enters the correct password and returns to the login screen again

Ubuntu Forgot password Resolve password

Command line interface Input STARTX command How not to enter the graphical interface

Tell me something stupid I did.

After entering the graphical interface, enter the startx in the terminal

Then, then reboot, you won't be able to get into the graphical interface.

How to break, combined with the above three posts,

1. Press SHIFT to enter recovery mode, and select the root command line execution pattern

2, under the root authority, mount-ra-o remount/

3, chown username:username ~/. Xauthority

4,reboot

When I enter startx at the Linux GUI terminal, what am I doing?