Shell uses a small note

The shell is the preferred system administrator for its stability, efficiency and flexibility.
1. Shell Introduction:
Command line: Refers to the interface for the user to enter a command, which itself simply accepts input and then passes the command to the command interpreter.
Shell: the command interpreter. Essentially, the shell is a program that provides a line-oriented, interoperable interface between the user and the operating system. The user enters commands at the command line, and the shell that runs in the background translates the command into the instruction code sent to the operating system.
Common shells are: BASH, TCSH Shell, Z-shell, and so on. The BASH shell is the shell that is installed and used by default.

2. How do I open the command line terminal?

(1) ctrl+alt+t. Br/> (2) ctrl+alt+f1~f7 can open the command line console, Linux default has 7 consoles, by default, the first 6 console is the command line console, the 7th is left to the X server.
(3) Search terminal in dash, open directly.
(4) Desktop icon.
3. Command line prompt:
BASH with a dollar hint sign ' $ ' as a prompt indicates that the user can enter a command. If the command is executed as root, then the shell prompt will become ' # '. Before Bash's dollar prompt, there is typically a piece of information, including the user name, host name, and current directory. A complete prompt is as follows:[email protected]:/home$.
5, command line completion:
When you enter the file name and command, you only need to enter the first few characters, and then press the TAB key, the shell will automatically complete the file name. If the characters you have typed begin with more than one file, you can press the TAB key two times consecutively, and the shell will give you a list of all the files that start with the characters you typed.
6. Wildcard characters:
: Used to match a string of any length in the file name.
？ : WithSimilar, but only one character is matched.
[]: Used to match all occurrences of the character in square brackets.
7. Permissions:
3 Rights owners: The owner of the file, the user of the file group, and others.
For a directory, the Execute permission actually controls whether the user can enter the directory, while the Read permission determines whether the contents of the directory can be listed; Write permissions control the creation, deletion, and renaming of files in the directory.
8. Equipment Files:
Linux uses device files to identify a particular hardware device.
There are two types of device files in Linux: Character device files and block device files.
A character device file refers to a device, such as a tape and serial line, that can read a character sequence of characters from it literal.
A block device is a device, such as a tape, used to store data and provide equal access to parts of the content.
and character devices are sometimes referred to as sequential access devices, and block devices are sometimes referred to as random access devices. Using block devices, as the name implies, can fetch data from any random location on the hard disk, while using a character device must be obtained from the serial line in the order in which the data is sent.
Owning a device file does not mean there must be a corresponding hardware device present, which simply indicates that Linux has the potential to handle this device.

Shell uses a small note