Introduction to X Window System

What is X Window System？

Unix Like Under the system GUI Windows System . An interface layer above the hardware , It is an application on the operating system , And it contains the network communication protocol . Now most of the distribution The use of X It's all by Xorg From the foundation X11 Software . So look at the common Linux The system can see X11 and Xorg Run the program .

Main components

X Window System It is a set of graphics user interface software which adopts network architecture , It mainly includes X Server and X Client Two components .X Server Managing hardware , Responsible for input and output display, etc .X Client Be responsible for accepting X Server The input and are for X Server Provide information . Note that it is different from the common client server structure ,X Server It's the hardware that manages the client , Including keyboard mouse and other devices input and graphics to the screen , It usually runs on the client ,X Client Provide X Server Information to be displayed , It is generally run on clients and remote servers . This is not the same as the general web Of CS The architecture is different .

1.X Server

Its main task is to manage hardware devices on client hosts , Including the keyboard 、 Mouse 、 Display and corresponding drivers etc . It tells you the action of the client input device X Client,X Client Is responsible for handling these actions .

2.X Client

It will Server The incoming input device acts to generate data and return the data to Server,X Server Show it on your own screen according to the returned information .X Client It is also called X Application. And there can be more than one X Client, They are independent of each other , So there may be overlap when it is displayed .X Client You don't need to know X Server Hardware configuration and operating system of , Just follow the network protocol .

3.X Window Manager

It's a special kind of X Client, Responsible for managing all the X Client. The ones mentioned above X Client Overlap may occur when displayed , So a tool to manage them , That is to say X Window Manager 了 . Responsible for managing the desktop , Window size , Overlap , Windows move equal arguments .Linux The common ones are ：

GNOME（GNU Network Object Model Environment）

KDE（K Desktop Environment）

twm（Tab Window Manager）

XFCE（XForms Common Environment）

With CentOS Of GNOME For example , Need to be in CentOS There is Xorg Of X Server The core , Responsible for the screen drawing , And then for the convenience of Windows Management , Need GNOME This window manager, For your own convenience , stay GNOME Add more windows application software on it , Such as Firefox、 Input method, etc , So we build X WIndow System. These elements often exist in one at the same time Linux On the mainframe .

4.Display Manager

The graphics login interface of the operating system , Its task is to provide login environment , And load the user selected Window Manager And language family and so on . stay CentOS On GNOME Provides GNOME Display Manager（gdm） The graphical interface login of .

X Window Start up process

Starting X Window System When , You must start the management hardware and drawing first X Server, And then load X Client. Basically , At present, they are all using WIndow Manager To manage the windows interface style . You can log in to the text interface of this machine after , Input startx To start X Windows ; It can also be done by diplay manager The login screen provided will enter the password of the account to log in to start X Windows . Starting from the command line entry is described below X The process of .

startx

After logging into the system from the command line , Input startx（shell Instruction code ）, Its task is to find the user or system preset X Server And X Client Configuration file of , It can also be in startx This is followed by a configuration argument , The format is as follows

startx [X client Arguments ] -- [X server Arguments ] # Such as startx -- -depth 16

Note that the argument follows with -- Separate , The front is client Settings for , And then server Settings for .

xinit

Actually startx It will start xinit,startx To help it find the set argument .

Grammar format

xinit [client option] -- [server or display option]

The system preset startx, Equal to

xinit /etc/X11/xinit/xinitrc -- /etc/X11/xinit/xserverrc

if xserverrc non-existent , It is

xinit /etc/X11/xinit/xinitrc -- /usr/bin/X

Simple execution xinit, The default of the system X client and X server It's like this

xinit xterm -geometry +1+1 -n login -display :0 -- X :0

X server Arguments

startx The following argument

If not , Then ~/.xserverrc

If not , Then /etc/X11/xinit/xserverrc

If not , Then simply execute /usr/bin/X

X client Arguments

startx The following argument

If not , Then ~/.xinitrc

If not , Then /etc/X11/xinit/xinitrc

If not , Then simply execute xterm

It will eventually load KDE perhaps GNOME,X Client Two commands in search of ,startkde and gnome-session, This is CentOS There are two main aspects of presupposition WIndow Manager.

In a nutshell , Start in command line mode X When , Use it directly startx find X Server And X Client Argument or configuration file of , And then turn on xinit Start X Windows System .xinit Load first X Server Find the default :0 This reality interface , And then load X Client To this X On the reality interface . and X Client It's usually GNOME perhaps KDE. In addition, use ctrl+alt+Fn Can switch different terminal screen .

X Start the process test

stay tty1 in , Start the first one X stay :1 The picture

X :1 &

return tty1 in

xterm -display :1 &

Again in tty1 in

xterm -display :1 &

xclock -display :1 &

xeyes -display :1 &

stay tty1 in , Start Window Manager

twm -display :1 &

&n