Linux beginner's guide and r language beginner's Guide

Linux beginner's guide and r language beginner's Guide
1. Why should we learn Linux?

Why should we learn about Linux? What value does Linux bring to us?

Linux gives me the feeling thatStability,Free,Good performance.

StabilityWhere is it reflected? We use PCs. The operating systems installed are windows xp, windows 7, and so on. If you open these operating systems for a week, your machine will be restarted, because the computer will become very slow, however, if you use Linux, you generally do not need to restart it for one month. If the machine is busy, it will be an exception. Here I am talking about personal PC, while many Internet companies use cheap PC servers. The current price is 2-3 W for each Server. There is essentially no difference between PC Server and personal PC, the same x86 processor architecture is also a complex instruction set, but the stability of PC Server is much higher than that of personal PC, and the performance and memory are also relatively high, but the cost is that the boot is relatively long, it usually takes 5 minutes, and the sound is also very loud. It is useless to buy a PC Server. Generally, PC Server Linux installation can be maintained for one year without restarting.

FreeWe should be clear that the windows operating system is not free, especially for enterprises, if windows is installed on each server, the operating system fees paid by enterprises are considerable, especially for Internet companies, if they have a large number of PC servers distributed across the country, they have to pay windows protection fees. In China, enterprises generally buy more than a dozen licenses in symbolic form, and the protection fee at the point of intersection is also passed (windows has backdoors, and enterprises will be troubled if they do not look for home computers). However, if enterprises are relatively large, the benefits are good, there are many machines, and a dozen licenses are not enough protection fees, so using free Linux is a good choice.

PerformanceLinux has made a lot of optimizations. For example, Linux will cache file directories and content in idle memory without virtual memory, but windows will certainly use virtual memory, even if the memory is sufficient. In terms of software, Linux has a huge range of open-source software support, web servers, cache servers, and database servers. These are all free options and are stable and mature products.

Quick fixing of Security and vulnerabilities: If you often play on the internet, you will most often hear that hosts are "no absolutely secure hosts 』! That's right! However, Linux has many supporters and many enthusiastic groups and individuals are involved in the development. Therefore, users can obtain the latest security information at any time and update the information at any time, that is, it is relatively safe.

Multi-Service and multi-user: Different from Windows systems, Linux Hosts allow multiple users to work online at the same time, and resource allocation is relatively public, which is much more stable than Windows single-task systems! This multi-task is a good Unix-Like function. How can this problem be solved? You can plan users of different levels on a Linux host, and the working environment for each user to log on to the system can be different. In addition, users in different regions can also log on to the host at the same time to use the resources of the host at the same time.

Suitable for embedded systems that require small core programs,Linux can drive the entire computer hardware and become a complete operating system as long as hundreds of KB of code in sequence, so it is quite suitable for the current operating system of household appliances or small electronic supplies! That's the "embedded" system of the hot-fried chicken! Linux is a very suitable microcomputer operating system for example, mobile phones, digital cameras, PDAs, household appliances, etc!

With so many advantages, the biggest drawback isLinux uses the "command column" terminal Terminal Mode for system management. In addition, there are no specific support vendors, insufficient support for games, and insufficient support for professional software, most of these shortcomings are not Linux problems, but some policy and commercial considerations are the biggest concerns. However, Linux is just a tool like other guest operating systems.

About authorization

Open Source)

1. When the software is released in the Open Source mode, it indicates that apart from the executable software itself, it must be accompanied by the release of the original code! Generally, Open Source software has several advantages: 1. Programmers usually release the software after the program is mature, so usually the reverse sequence has a very good Constitution when it comes to the prototype;

2. in the spirit of Open Source, I believe that when the programmer releases the original code, other programmers will accept the original code and change the parameters to the style they need, so it will be improved through its own learning, and improved and removed from the bug, so the debug function of the program will be faster than the traditional close source!

3. The second program is accompanied by the original code. Therefore, the system will not easily have Trojans or some security vulnerabilities, which are relatively more secure.

Close Source

Compared with the Open Source software, the original method is released. The Close source program only introduces executable binary program (binary program. The advantage of this kind of software is that it is maintained by a dedicated person and you do not need to change it. The disadvantage is that flexibility is greatly reduced, and users cannot change the program to the desired style! In addition, if a trojan program or security vulnerability exists, it will take quite a while to correct the error! This is also a common selling method for software related to copyright.

However, I personally think that Linux is really powerful in the field of servers, but on my PC, I always feel that it is not easy to use. At present, it is still easy to use windows, even if it is the best Linux on my desktop, ubuntu is not as good as windows, windows has a good user experience, convenient operation, personal software support (such as online banking ).

2. Select a Linux release version.

The first thing to learn about Linux is to select a Linux release version, which can be installed on virtual machines or physical machines. For BeginnersIt is best to use a virtual machine. The first thing for Linux beginners is to see many Linux branches and dizzy. What is the difference? Why does Linux have many versions instead of just one? This is actually the case,Linux is actually an operating system kernelHowever, in addition to the kernel, an operating system also has a user interface and application software, such as the windows we use, as well as the windows Kernel. In addition to the windows Kernel, there is also a GUI for windows, windows office and other applications. Linux is a free and open-source kernel. Every manufacturer can go to the kernel on the Linux kernel official website.

Currently, Linux only has several branches:Redhat, ubuntu, debian, suse. Many other linux releases are derived from these branches. For example, the Chinese Red Flag and centos are derived from redhat.

In the Server field, I personally think redhat is doing the best now.,Ubuntu is the best in the desktop FieldBut the biggest purpose of learning Linux is to learn the field of Linux servers. Therefore, I recommend the redhat version.

The linux textbooks in the school are outdated. Most of them are Redhat Linux 9 tutorials. However, due to the hard drive relationship, Redhat Linux 9 cannot be installed on the current physical machine, including myself, he was misled by university textbooks.

After Redhat Linux 9, redhat did not maintain the open-source version of Redhat, so he directly released its commercial version Redhat Enterprise Linux 2, which currently has Redhat Enterprise Linux 6, but the stability of 6 is unclear. I personally recommend using Redhat Enterprise Linux 5. Please download Redhat Enterprise Linux 5 on your own.

Although Redhat Enterprise Linux is a commercial version, you can still use it normally if you do not enter the serial number during installation, but you cannot update the software on the redhat official website, here we will mention CentOS. Because Redhat Enterprise Linux is a commercial version, the CentOS organization bought the source code with redhat and re-compiled it for free, for free, you can update software on the centos official website, including systems using Redhat Enterprise Linux, or on the centos official website. You may also have doubts that since centos and redhat are both the same, except for different names, centos is not selected. In fact, there is no difference. Centos 5.5 is exactly the same as Redhat Enterprise Linux 5.5. You can choose centos to install it and learn from redhat tutorials.

3. Introduction to Linux

After selecting the Linux release version, you will want to learn about Linux.

1. Of course, Linux is installed. Please go online and google or Baidu, download the redhat linux 5 installation CD, then install vmware and install it on your own.

2. Run the command multiple times. Read Only, do not practice, everything is floating cloud. By default, redhat 5 is installed, and the startup of redhat 5 has a graphical interface. However, it is recommended that the graphic interface be used less often, which is not good for learning Linux. You must try to use the character interface as much as possible to get used to it. In practice, the probability of using a graphic interface in Linux is almost zero. Therefore, you can learn the technical value of the graphic interface, which is almost zero and cost-effective.

4. How to learn about Linux

1. The first thing to learn about Linux is to learn the basics of Linux.Laruence's private dishLinux basic file, which describes Linux Files, disks, networks, processes, etc. After reading this book and executing commands one by one, you can get started with Linux.

2. The second thing to learn about Linux is to use Linux. As mentioned above, Linux is most useful in the server field, so the second step you need to learn is to set up servers.Laruence's Private food Linux server filesThis book introduces many server assumptions and does not have to finish all Server SETUP steps. I personally think we can first look at the foundation of server setup, and then look at how to build web servers, ftp servers, telnet servers, and ssh servers. Learn how to build and manage these servers, and then select other servers based on your personal interests and needs.

3.Advanced-Programming. Here, you just use Linux. Maybe you can learn a little shell programming, learn simple shell, and write scripts. But to get familiar with Linux, you must learn Linux programming. For example, how does the Linux pipeline work, how does the deamon process in Linux work, and why does nohub allow a process to run in the form of daemon, even if shell is disabled, the process will not be shut down. Now that you have learned how to program the Linux environment, you will be very open. Here I recommend 《Advanced Programming in UNIX environmentThis book is the Bible for Linux/Unix programming, which is an amazing work.

4. now, you can have a certain understanding of Linux/Unix and have a certain foundation. Next, you should select the direction you are interested in based on your interests, you may want to learn according to your work direction (work is not your interest in many times). Master leads the door and practices are personal. The above learning steps are the simplest steps that I can think, the more things you learn, the more confused you will be.