What is the difference between using the 'X -config' command and the 'startx' command

Question

I get very different results when using

X -config /etc/X11/xorg.conf

than just plain

startx

Namely, that the 1st command just gives me a black screen, while startx actually shows some X windows.

Answer 1

As the startx man page says,

startx - initialize an X session
The startx script is a front end to xinit that provides a somewhat nicer user interface for running a single session of the X Window System. It is often run with no arguments.

The X command runs the X server. startx does that and also initializes the session, i.e. runs what is specified in the configuration files, typically the windowing environment, xterm etc.

To determine the client to run, startx first looks for a file called .xinitrc in the user’s home directory. If that is not found, it uses the file xinitrc in the xinit library directory.

To illuminate further, startx uses these files:

   $(HOME)/.xinitrc         Client  to  run.  Typically a shell script which runs many programs in the
                            background.

   $(HOME)/.xserverrc       Server to run.  The default is X.

   /usr/lib/X11/xinit/xinitrc
                            Client to run if the user has no .xinitrc file.

   /usr/lib/X11/xinit/xserverrc
                            Server to run if the user has no .xserverrc file.

Answer 2

the startx uses the files listed in the other reply,while the "-config" option uses a user-specified configuration file