< training | Changes to the >linux login interface on the third day and Richard Stallman, free software movement

Before I write a blog, I want to say two points:

1. Admit a mistake, yesterday wrote the training the next day, I put redhat6.7 written Linux6.7, thank the enthusiastic personage's point!
2. Yesterday wrote the article name is too long, today's improvement, the content feeling expressed not all, I hope you understand!
3. The official told me is that the installation configuration class articles cannot be put into the homepage, today, although a little, but the main part of the gun, Linux and TCP/IP, as well as the knowledge.

long-awaited Linux operations, Oracle "training class" finally started, I have been a long 4.5 months of Linux operation and maintenance, Oracle training, every day I will study hard, evening back I will try to update the tutorial, including today learned what knowledge points, Using what method, what tools are used, where tools are shared and so on, and strive to make every interested, concern me, not concerned about my old driver can learn a little extra knowledge in their leisure time, that day you will use a little!

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Thank you for your support, I would like to say two sentences, the first four or five days of training, you may learn the basis of knowledge, but also hope that people look at the two eyes, pointing out; no one follows me from the basics, but don't take it for granted that it's simple, and you're going to have more problems than you think when you actually do it. Some of you can easily solve, but there are some problems I believe not everyone can quickly solve, so the knowledge of this thing is a step by step accumulation, thank you for your support!

I'm here to make sure that over the next few days, you'll be able to learn a lot and very useful knowledge about Linux, Oracle, cloud computing!

The third day of the classes:

　　The main content outline:

1. Install fonts for the system
2. Modify Login Interface Login Information
3. Realization of listening to songs and watching movies in Linux
4. Install the Chromium browser and solve the problem
5. The knowledge of gun
6. Learning from the Linux kernel
7. Understanding of OSI and TCP/IP models
8. Understanding of IP addresses, Gateway netmask, GW, and DNS

Detailed Explanation:

• Install fonts for the system

　We know that the newly installed Redhat system, in the terminal input in Chinese, will find the font size is very small, this is because our system comes with the font of the Chinese display is not particularly perfect, so we want to install the font, here I provide a wide range of Ubuntu fonts, If you need comments on Windows fonts Private chat, I can provide. Here are three ways to install fonts:

① in Redhat's graphical interface, double-click the Font Viewer to open and install.

② Copy the fonts you need into the /usr/share/font directory in the Redhat graphical interface and select them.

③ If there is no graphical interface installed, then use the CP command to copy to the font directory.

　　

• Modify Login Interface Login Information

　　Login interface changes are limited to the installation of the graphical interface of the drivers, we are in the login interface, we will see our usual login user information, if I do not want to let others see I have created what users, want to hide the information of the logged-in user, we how to set. Here are the steps we set up:

① First we enter in the terminal: Find the following section

[Email protected]~#VI /etc/gdm/gdm.schemas

　　

　　The meaning of the ② diagram is:

The first greeter indicates the user that will be displayed in the login screen, no user in default, we add the users we want to display.

The second greeter indicates that the user that opens the drop-down list will be displayed, and in default we can delete the root user and display it directly.

The third greeter indicates whether to show all users, and the default to change the true to false, so that others do not know that we have created those users.

• Realization of listening to songs and watching movies in Linux

　　As you know, in a Linux system, whether it is a music player or a video player, the supported formats are very few, so we want to install a suitable video player to meet our needs. Here I recommend a SMPlayer player. The source package I will also upload up. RPM format, install this will not need me to say, will play the Linux people, the software will always install it!

• Install the Chromium browser and solve the problem

　　There may be a lot of people who are not particularly willing to use Redhat's own Firefox browser, but for Chrome, I'll teach you how to install Chrome in Redhat. Here we install a chromium browser. The steps are as follows:

① is not the root user to switch to the root user:

[Email protected]~#su -

　　② Execution:

[Email protected]~ #cd/etc/yumrepos.d

　　③ Execution:

[Email protected]~#wget http://People.centos.org/hughesjr/chromium/6/chromium-el6.repo 

　　So we have installed the browser, there will be a problem, if you are always using the root user, then run chromium error "chromium cannot be run as root", how to solve?

　　

• The knowledge of gun

　　What the gun is, the GNU program began in 1984, and the ultimate goal was to complete a complete operating system based on free software. Here is an article about Richard Stallman, the founder of Gun, whose name is Richard Stallman and the free Software movement, which focuses on some of the stories of gun and Richard Stallman, Very good! Worth a look! Here are three software concepts: free software , open source software , proprietary software , and a picture that explains all of them.

　　

• Learning from the Linux kernel

　　The concept is not much, the direct topic, how to view the kernel version of your Linux system:

[Email protected]~#uname -R

　　

　　My kernel version is 2.6.32-573.e16.x86_64, explaining a wave, 2.6.32 is the version number of the Linux kernel, Before 3.0, 2 for the major version number, 6 for the minor version, 32 for the last version, the modified Chengdu size decided to change that number, the minor version number of the odd representative of the beta version, even for the stable version, the following 573 is the number of changes to the Linux kernel Redhat Company, this represents the No. 573 time the change. X86_64 stands for 64 bits. It's just so much.

• Understanding of OSI and TCP/IP models

　　Here we need to meet the OSI seven layer model, the TCP/IP four layer model. The construction of the model is believed to be casual Baidu a bit to know. Here I'll talk about the difference between TCP and UDP:

①TCP is a connection-based protocol, which means that a reliable connection must be established with the other party before the data is formally sent and received.
②UPD is the protocol that corresponds to TCP. It is a non-connected protocol that does not establish a connection with the other, but sends the packet in the past directly.

We make a metaphor, TCP is like we call, you must be sure to answer (three handshake), to transmit data; UDP is like texting, I don't care if you are in the absence of the phone, I just send the past on the line, that is to achieve the UDP protocol transmission speed, but also not secure.

• Understanding of IP addresses, Gateway netmask, GW, and DNS

　　About IP address, IPV4 has been exhausted, used up, IP address is divided into five categories: ABCDE, which can be used on the Internet or by the user of A, B, C three class, and the Class D as a multicast address, Class E as a research reserved address segment.

　　

A picture wins thousands of words. At the same time we have to note that the IP address is divided into private addresses and public addresses .

　　Public IP Address:

• Public IP for Class A:

  1.0.0.0~9.255.255.255

  11.0.0.0~126.255.255.255

• Public IP for Class B:

  128.0.0.0~172.15.255.255

  172.32.0.0~191.255.255.255

• Public IP in Class C:

  192.0.0.0~192.168.255.255

  192.169.0.0~223.255.255.255

Private IP Address:

• Class A private IP address:

  10.0.0.0~10.255.255.255

• Class B Private IP address:

  172.16.0.0~172.31.255.255

• Class C Private IP address:

  192.168.0.0~192.168.255.255

　　

　　DNS is what, the domain name resolution server, relying on it to find the URL you want to visit and then send the information to your computer.

The capacity inside it is very good, store all the domain name and the corresponding IP, you enter a domain name in the browser, it can help you find (parse) IP address, and access. The existence of the domain name determines the existence of DNS, we always can not remember the IP address every day to access it, so tired people.

Summarize:

　　Update is not particularly fast, these days to learn the things are preparatory, so a lot of people have learned, but I promise that after the foundation, is what you want to learn.

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Public number : program ape Wild Banana "Public number: You can download to my tutorials, tools, notes, and other resources I share, resources may be uploaded later today, but I will update every day." "

　　

< training | Changes to the >linux login interface on the third day and Richard Stallman, free software movement