Basic knowledge about the Linux graphical interface __linux

Author: Gucuiwen email:win2linux@163.com

Many Linux beginners don't know what the relationship is between Linux and X, between x and Xfree86, X and KDE, GNOME, and so on. Often confusing concepts, I would like to explain the relationship between X,x11,xfree,wm,kde,gnome and so on in a more comprehensible way. Because of my limited level may be wrong, please correct the master.

Linux itself does not have a graphical interface, Linux is now the implementation of the graphical interface is only the application of Linux under the implementation of .
Graphical interface is not a part of Linux, Linux is just a command line operating system, Linux and Xfree relationship is equivalent to the same year's DOS and WINDOWS3.0, windows3.0 is not a stand-alone operating system, it is only the expansion of DOS , is a DOS application-level system, not a stand-alone operating system, the same xfree is only one application under Linux. Not part of the system, but the presence of X makes it easier for users to use the computer. WINDOWS95 and later versions are not the same, their graphical interface is part of the operating system, the graphical interface is implemented in the kernel, without a graphical interface windows will not become windows, but Linux is not the same, no graphical interface Linux Also Linux, a lot of Linux WEB servers do not install X server at all. This is also one of the important differences between WINDOWS and Linux.

Two, X is an agreement, not a specific software
X is the protocol, just like the HTTP protocol, the IP protocol. This concept many beginners even learn LINUX for some time people are confused, an X-based application needs to run and display content when he joined to the X server, began to use the X protocol and server conversation. For example, an X application will output a circle on the screen, so he uses the X protocol to say to the X server: Hey! I need to draw a circle on the screen. x application is only responsible for telling the X server where in the screen with what color to draw a large circle, and the specific "painting" action, such as how the circle generated, with what graphics card driver to command the video card completion and so on work is done by the X server. X server is also responsible for capturing the keyboard and mouse action, assuming that the X server caught the left mouse button was pressed, he told the X application: Dear application sir, I found the mouse was pressed, do you have any instructions? If the X application is designed to draw a square on the screen when the mouse Zuojian is pressed, x app says to x server: Please draw a square again, of course he will tell the server where to paint with what size square, but do not care about how to draw--that is the server thing.
Then the protocol needs specific software to implement, and that's what I'm going to talk about here:

Iii. the relationship between X and XFree86 .
With a protocol, you need specific software to implement this Protocol. It's like we have traffic rules. The traffic police are required to maintain the order of transportation according to the regulations. Xfree86 is such a "traffic policeman" to achieve the agreement according to the law. He did the X-Protocol to complete the on-screen tasks presented by the X. Application. Of course, not only a certain traffic police can go to maintain and implement this regulation, such as also by traffic wardens to achieve traffic regulations, when necessary, the police can intervene, of course, if they must understand the traffic laws, that is to understand the agreement. Therefore, the implementation of the X-protocol software is not only XFree86, XFree86 just to implement the X protocol of a free x server software. Commercially used MOTIF, there are now XORG, and there are a lot of little X-Server software written by enthusiasts. You can even run an X server on Windows so that you can run an X application on a Linux system and then display it on another Windows system. how magical. You can use Google to find such an X server software. But the most common on LINUX is XFree86. (Linux distributions are now Xorg) by the way, Apple Computer graphics interface is also the X protocol, and is considered to do the best X protocol graphics interface, and his implementation of the X protocol is in the system core, so the performance is significantly better, which is why it is Many large three-dimensional graphic design software is the reason on the Apple platform.
To facilitate understanding of the HTTP protocol to compare:
Protocol is HTTP (Hyper Text transmission protocol)
Common servers to implement this protocol are: Apache IIS, etc.
The clients requesting these servers to transfer files are: IE, MOZILLA, NETSCAPE, and so on.
Protocol is X
The common servers to implement this Protocol are XFREE86, Xorg, xnest, etc.
Customers requesting these servers to complete the display task: all X applications.
Only the HTTP protocol's servers and clients are usually implemented between two different computers (servers and clients), so it's easier for people to understand this. The X-protocol server and client programs are usually on the same computer, so many users find it difficult to understand. Since it is a protocol, it is definitely not platform-independent, so you can have the X application displayed on any remote computer that has an X server installed. It is even displayed on a Windows system equipped with a Xnest server. In most cases, the X application uses the native x server, and the X server outputs the results to the local monitor. That's why a lot of people don't understand that X is a protocol.

What is the relationship between X and X11R6? ?
Don't know if beginners have noticed/usr/x11r6 this directory, which is the default installation directory for Xfree
X11R6 is actually X Protocol version one release 6
(x Agreement 11th edition sixth issue) meaning, that is the current X protocol is the 11th edition, then after 6 minor amendments. Different versions of the X protocol are not able to communicate. Just as we are now IPV4 and IPV6 can't communicate, but don't worry, now the X server Software and x applications follow X11R6.
In addition, these versions of XFree86 3.3.6 XFree86 4.3.6 are the version numbers that implement the X protocol's software XFree86. This is often a beginner's concept of high confusion.
Protocol version and the version of the software that implements the protocol--Do you know the difference between the two concepts?

Five, x what is the relationship between the server and the WM (Windows Manager window manager) .
How do we start the graphical interface at ordinary times?
It would be a shame if you entered the graphical interface as soon as you opened your own. Because you missed a good time to learn about the X server start process. But it doesn't matter. You open a XTERM input:
Init 3
You can safely return to the character interface.
Well, when you're done with the following experiments, you fully understand what the relationship is between X and the WM (Windows Manager window manager).
First enter the following command:
#startx
The starting graphical interface you see is a peaceful time to use the same complete graphical interface operating environment.
You can maximize, minimize, move, close windows, and so on.
Press Ctrl+alt+backspace to back up the character interface.
Input:
#xinit
Start the graphical interface again and you see what you see in a XTERM. and can't move. But you can enter the command in this XTERM to open the X application, if I enter:
#mozilla
Open the browser, you see the browser is different from the usual? He's in the middle of the screen, can't move, can't minimize