Linux practical articles-practical instruction study notes (detailed)

9.3 Help instructions

9.3.1 Introduction

When we are not familiar with an instruction, we can use the help instruction provided by Linux to understand how to use this instruction.

9.3.2man get help information

• Basic syntax
  man[command or configuration file] (function description: get help information)
• Application examples
  Case: View the help information of the 1s command
  

9.3.3 help command

• Basic syntax
  help command (function description: get help information for shell built-in commands)
• Application examples
  Case: View the help information of the cd command
  

9.4 File Directory Class

9.4.1 pwd command

• Basic syntax
  pwd (function description: display the absolute path of the current working directory)
• Application examples
  Case: Display the absolute path of the current working directory
  

9.4.2ls instruction

• Basic syntax
  ls [option][directory or file]
• Common options
  -a: Display all files and directories in the current directory, including hidden ones.
  -l: display information in a list
• Application examples
  Case: View all content information of the current directory
  
  

9.4.3 cd command

• Basic syntax
  cd[parameter] (function description: switch to the specified directory)
• Common parameter
  absolute path and relative path
  How to understand absolute path and relative path:
  
  cd~ or cd: go back to your home directory
  cd... go back to the upper level of the current directory
• Application Examples
  Case 1: Use an absolute path to switch to the root directory
  cd/root
  Case 2: Use a relative path to the /root directory
  Here we need to know which directory the user directory is in, to write this command, suppose it is in /usr/lib
  cd ././root
  Case 3: Return to the upper-level directory
  cd of the current directory ...
  Case 4: Return to the home directory
  cd
  cd~

9.4.4 mkdir instruction

The mkdir command is used to create a directory (make directory)

• Basic syntax
  mkdir [options] the directory to be created
• Commonly used options
  -p: create a multi-level directory
• Application examples
  Case 1: Create a directory /home/dog
  
  Case 2: Create a multi-level directory /home/animal/tiger
  

9.4.5 The rmdir command

• Introduce the
  rmdir command to delete empty directories
• Basic syntax
  rmdir [option] empty directory to be deleted
• Application examples
  Case 1: Delete a directory /home/dog
  
• Usage details
  rmdir deletes an empty directory. If there is content in the directory, it cannot be deleted. Tip: If you need to delete a non-empty directory, you need to use rm-rf to delete the directory