1) ls – List directory contents

• Function: Displays files and directories.

• Syntax:

  ls          # list files
  ls -l       # detailed listing
  ls -a       # show hidden files
  
  

• Lesson: Always use ls -l to check permissions and ownership.

2) cd – Change directory

• Function: Navigate directories.

• Syntax:

  cd /home/user
  cd ..    # go up one level
  cd ~     # go to home directory
  
  

• Lesson: Always confirm location with pwd before major actions.

3) pwd – Print working directory

• Function: Shows the current directory.

• Syntax:

  pwd
  
  

• Lesson: Crucial when navigating deeply nested directories.

4) mkdir – Make a directory

• Function: Creates new directories.

• Syntax:

  mkdir projects
  mkdir -p folder/subfolder
  
  

• Lesson: Using p saves time by creating nested folders in one step.