Common linux commands (fourth day) -- bash

When I was learning linux, I skipped some important things. For example, partition. In addition, vim has a deep learning experience. Partition is not learned because I installed a virtual machine. I don't know why, and the formatted partition cannot be properly displayed. As for vim, I have learned about simple addition, deletion, modification, and query. In linux

When I was learning linux, I skipped some important things. For example, partition. In addition, vim has a deep learning experience. Partition is not learned because I installed a virtual machine. I don't know why, and the formatted partition cannot be properly displayed. As for vim, I have learned about simple addition, deletion, modification, and query. Files can be edited smoothly in linux. I don't want to go deep into it. It may be much easier for me to go back and look at these questions when I chew off this book "laruence's private dish.

Now, I want to take these days off. I can hardly learn. I am not as inspirational as I planned, so I try my best to act as an inspirational object and touch myself and others. Stick to + the correct direction, if nothing happens. We can quickly achieve success and realize our own value. But every day I bury myself in learning, and I am not happy at all. After several years of hard work, you can enjoy yourself. It's better to be happy every day. Do not force yourself so hard every day. As long as you work hard every day, you only need to study purely and do not put too much pressure on your workload. You can give yourself a small vacation on weekends every week to indulge yourself completely. Don't want to learn, just want to play. Isn't it good?

I always believe in the brainless dumb: the person who loves to laugh is lucky. Happy people will stay away from bad luck.

 

An operating system includes

Hardware

Kernel

Shell

Hardware is just a bunch of parts without thinking. Only hardware and computers cannot work at all. Just like a group of empty people, without a well-regulated leader, a group of scattered people cannot form combat power.

The kernel is able to identify various hardware, manipulate each hardware, and let the hardware work according to instructions. However, not every user can directly send a command to the kernel to allow hardware to work. First, most users do not have command lines and have no professional background. Second, if you are allowed to operate the kernel at will, it will bring a great security risk to the system. Hackers can easily intrude into your computer.

Based on the above reasons. Shell appears. Shell is built on the kernel, and various applications are built on the shell. For example, cool dog music software: you click to play music on the software. The click behavior is first translated to the kernel through shell. The kernel then transmits this behavior to the hardware, so the music is played.

We usually use a graphical shell in windows. shell has been integrated with a graphical interface, which is a major innovation of Microsoft. In the past, everyone thought that linux was not easy to use and it was very difficult to use. The first reason is that linux is a text interface and black commands make people look scared. The second reason is that there are too few linux software. We cannot meet our entertainment needs. However, these situations have improved a lot in recent years. There are also amazing graphics in various linux releases. Not inferior to windows. For example, the wubantu system, such as the centos7 series, and the domestic deep linux are all very nice. As for the application software, I think it is much less than windows. However, if you do not play games, the software provided by linux is enough.

It's a little far away. let's get back to the question. Linux not only has a graphical shell, but also has a command interface shell.

When I install linux, it is the minimum installation. by default, the graphic interface is not installed.

The significance of learning the command interface shell is as follows (for more information, see the opinion of laruence)
1. force the first installation, and force the town building.

2. learn the shell of the command line to understand the essence of the command. Able to locate and solve problems accurately and quickly.

3. the command interface is faster and safer than the graphical interface in remote management. Because of its overseas business, the company's servers are not from Hong Kong, but from the United States and the United Kingdom. Due to the international network speed problem, you can remotely use graphic interface to control it.

 

As mentioned above, shell is just a translator who translates user behavior. Therefore, since it is a translator, it is impossible to have only one translator. There are many translators in the history of linux development. Bash, C shell, K SHell, TCSHl, etc. We usually use the Bourne Again shell (bash for short). why is such a name? That's because the first popular shell was developed by Steven Bourne. In order to commemorate it, it is such a shell. It is a shell starting with Bourne. It has a long history. Think about it, as well as outsiders.

You can use cat/etc/shells to view the shells that can be used in your system.

Bash is the default shell in linux and the designated interpreter. The main advantages include:

Command memory function: historyde function. By default, more than 1000 records can be recorded.

The tab key command and path completion function. It's just a lazy favorite. just press a few tabs to complete a line of regular paths. mom no longer needs to worry about my memory.

Command alias setting function. Alias is widely used.

Job control, foreground, and background control.

Script function. O & M engineers love it most.