Reading Notes: Linux administrator Guide

Linux administrator Guide

Chapter 2 similarities and differences between Linux releases and Windows NT

1.3.1 comparison of single-user, multi-user, and network users

Windows NT was designed based on the idea of Bill Gates, the founder of Microsoft, that is, a computer, a table, and a user. To facilitate discussion, we call this situation "single user ". According to this arrangement, two people cannot run software such as Microsoft Word concurrently on the same computer at the same time. (Of course, from another point of view, people may think that if someone wants to run a huge program like word together, his brain may be somewhat problematic !)

Linux follows the principle of the UNIX operating system. Unix was initially developed by Bell Labs in the 1970s S and runs on a PDP-7 computer shared by the entire department. This requires a design that allows multiple users to log on to the central computer at the same time. At the same time, people can edit files, compile programs, or perform other work. The operating system on the central computer is responsible for managing the details of "sharing", and every user seems to be exclusive to the entire system. This kind of "multi-user" traditionally exceeded 1980s to 1990s, while other types of UNIX operating systems were also similar. The Linux operating system appeared in the early 1990s s, so it also supports multi-user operations.

1.3.2 GUI and operating system kernel are relatively independent of each other

Based on the design concept of m a c I n o s h, the Windows NT developers use its graphical user interface.

(Graphical user interface (GUI) is integrated with the core of the operating system. They complement each other and are indispensable. The advantage of tightly integrating the operating system with the user interface is that the operating appearances of all components of the system are consistent. Although Microsoft does not strictly emphasize the rules as Apple does, for the sake of application appearance interface, most developers prefer to maintain the same basic visual and operating modes in the same application.

Linux (and UNIX in the general sense) Operating Systems separate the user interface from the operating system. User interfaces such as the X-Windows system run as a user-level application, which makes it more stable. If the graphical user interface (for both Linux and Windows NT, their respective g u I is quite complicated) is faulty, the Linux operating system kernel will not be paralyzed. Another difference between X-Windows and NT's graphical user interface is that it is not a complete user interface: it only defines how to draw basic object elements on the display screen and how to control them. X-Windows has the ability to draw windows on the display screen of another workstation in the network.

1.3.4 comparison of registry files and text files in Windows

I personally think the Registry (r e g I s t r y) file in Windows NT can be called the highest level in the System Configuration database-thousands of data items, only a few of them have complete annotations, some of which are saved on the server and some on the client.

However, the Windows NT Registry is too difficult to handle. Although theoretically it is a good thing, every time I deal with the Registry, I am so embarrassed.

L The I n u X operating system does not have the "Registry" file. This has both advantages and disadvantages. The advantage is that various configuration files are usually saved as a series of text files (think about the. I files in Wi n d o w s before the registry appears ). This means that readers can use their preferred text editing programs, not just software tools such as r e g e d I t, to process configuration files. In most cases, this also means that the reader can add some comments to these configuration files at will, so that after six months, the reader can remember why he wants to make such a special setting. L most configuration files in the I n u X operating system are stored in the/etc subdirectory or a sub-subdirectory of it.

The disadvantage of not having a registry file is that the configuration file does not have a unified standard writing method. Each application or server program has its own format. Today, many applications are bundled with some g u I-based software configuration tools. In this way, you can easily perform some basic configuration work. If you need to make more complex adjustments, you can manually edit the corresponding configuration file. In practical applications, using text files to save configuration information is usually an effective method. These files are rarely modified after they are configured. Generally, they are text files that are easy to read and understand and can be easily understood when needed. In addition, you can easily write a script program, use it to read the same configuration file, and modify its behavior as needed. This is especially helpful for the automation of server maintenance operations, and automatic maintenance operations are crucial for a large site with multiple server hosts.

 

Linux system yiben Tong

1. network functions in Linux

Tc p/I p was integrated into the L I n u x system from the very beginning, and its implementation was completely rewritten. At present, TCP/IP has become the most robust, fast, and reliable part of the L I n u x system. It is also a key factor for the success of the L I n u x system.

3.1.4 appletalk protocol set

Appletalk is Apple's Network Interconnection protocol. It provides a peer-to-peer model and basic network functions such as file sharing and print sharing. Each computer can be set as a client and a server, but the necessary hardware and software must be installed on each computer.

Linux provides a complete set of appletalk network functions. Netatalk is the core layer of the appletalk protocol. It was originally written for the bsd unix system.

3.7.3 redundant network

Ipat (IP address takeover) is called IP address takeover. When a network adapter fails, its IP address should be taken over by the network adapter of the same node or another node. MAC address Takeover: After the IP address takeover is completed, all nodes on the network should upgrade their ARP cache.

 
FTP command: