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Command Line Basics

The command line interface (CLI) is your gateway to powerful system control. Master these fundamentals to efficiently navigate and manage Linux systems.

Getting Started with the Terminal​

What is the Command Line?​

The command line is a text-based interface where you type commands to interact with your computer. Unlike graphical interfaces, the CLI provides direct, precise control over your system.

Opening the Terminal​

  • Ubuntu/Debian: Ctrl + Alt + T
  • macOS: Cmd + Space, type "Terminal"
  • Windows: Use WSL (Windows Subsystem for Linux)

Essential Commands​

# Show current directory
pwd

# List files and directories
ls
ls -la  # Detailed listing with hidden files

# Change directory
cd /path/to/directory
cd ~     # Go to home directory
cd ..    # Go up one level
cd -     # Go to previous directory

File Operations​

# Create files
touch filename.txt
echo "Hello World" > file.txt

# View file contents
cat filename.txt
less filename.txt  # Paginated view
head filename.txt  # First 10 lines
tail filename.txt  # Last 10 lines

# Copy, move, and delete
cp source.txt destination.txt
mv oldname.txt newname.txt
rm filename.txt
rm -rf directory/  # Remove directory and contents

Directory Operations​

# Create directories
mkdir new_directory
mkdir -p path/to/nested/directory

# Remove directories
rmdir empty_directory
rm -rf directory_with_contents

Command Structure​

Every Linux command follows this pattern:

command [options] [arguments]

Examples:​

  • ls -l /home - List detailed info for /home directory
  • cp -r source/ dest/ - Copy directory recursively
  • grep -i "error" logfile.txt - Search for "error" (case-insensitive)

Getting Help​

# Manual pages
man command_name
man ls

# Quick help
command_name --help
ls --help

# Command information
which command_name
type command_name

Practice Exercises​

  1. Navigation Practice:

    • Navigate to your home directory
    • Create a directory called "aws-practice"
    • Navigate into it and create subdirectories: "scripts", "configs", "logs"

  2. File Management:

    • Create a file called "server-info.txt"
    • Add some text content to it
    • Copy it to each subdirectory
    • List all files recursively

  3. Exploration:

    • Explore the /etc directory
    • Find configuration files
    • Use grep to search for specific content

Next Steps​

Once you're comfortable with basic navigation and file operations, you'll be ready to explore the Linux File System structure and organization.

AWS Connection​

These command line skills directly apply to:

  • Managing EC2 instances via SSH
  • Configuring AWS CLI
  • Automating tasks with shell scripts
  • Troubleshooting cloud infrastructure

Lesson Quiz

Test your command-line fundamentals. You can start, skip, or proceed to the next lesson.

Skip quiz → Next lesson

Lesson Summary

Key command-line concepts to remember. Use Save as PDF to export these flash cards.

pwd

navigation
Prints current working directory path.

ls -la

listing
Lists files with details including hidden files.

mkdir -p

directories
Creates intermediate directories as needed.

grep -i

search
Case-insensitive search within files.