Basic principles of Linux:
1. It is composed of small programs with single purpose: combining small programs to complete complex tasks;
2. All documents;
3. Try to avoid capturing user interfaces;
4. Save the configuration file in plain text format;
There are two interfaces for users to interact with the operating system:
GUI interface: there are three graphics —– > gnome, KDE and xface
CLI interface: command prompt (prompt), bash (shell)
#Represents root user and $represents ordinary user
At the command prompt, enter the command, and the shell will pass the command to the kernel. The kernel will judge whether the program has execution permission, whether it can be executed, and where to start execution.
If the program fails to execute, the kernel returns an error message through the shell.
Command + option (modify the execution mode of the command) + parameter (the target of the command)
For example: LS – A / etc/