Basic Command Line Navigation

Learn how to navigate the filesystem using basic commands like pwd, ls, and cd.

Introduction

Navigating the filesystem is a fundamental skill when working with the command line. In this lesson, you’ll learn how to use basic commands to find your way around the Raspberry Pi OS filesystem.

Learning Objectives

• Understand the structure of the Raspberry Pi OS filesystem.
• Learn how to use the pwd, ls, cd, clear and history commands.
• Differentiate between absolute and relative paths.

Understanding the Filesystem Structure

The Linux filesystem is organized in a hierarchical structure, starting from the root directory (/). Every file and directory is nested within this structure. Here’s a basic overview:

• / : Root directory, the top level of the filesystem.
• /home : Contains user directories, like /home/pi for the Raspberry Pi user.
• /etc : Configuration files for the system.
• /var : Variable data, such as logs and temporary files.
• /usr : User programs and data.
• /bin : Essential system binaries.
• /lib : Shared libraries.
• /opt : Optional software packages.
• /tmp : Temporary files.

The pwd Command

The pwd (print working directory) command displays the current directory you are in. This is useful to know where you are in the filesystem.

pwd

The ls Command

The ls (list) command lists the contents of a directory. You can use it to see files and subdirectories within your current directory.

ls

You can also use options with ls to get more detailed information:

ls -l

The cd Command

The cd (change directory) command allows you to navigate between directories. For example, to move into the Documents directory, you would type:

cd Documents

To return to the home directory, simply type:

cd $HOME

To back up one directory, use:

cd ..

Absolute vs. Relative Paths

• Absolute Path: A path that starts from the root directory /, e.g., /home/pi/Documents.
• Relative Path: A path relative to the current directory, e.g., Documents if you are in /home/pi.

Clearing the console

To clear the terminal screen, you can use the clear command:

    clear

This will clear the terminal screen, making it easier to read the output of new commands.

History Command

The history command is a useful tool that shows you a list of the commands you’ve previously run in the terminal. This can help you remember commands you’ve used before or quickly repeat them without typing them out again.

To see your command history, simply type:

history

This will display a numbered list of your recent commands.

Re-running Previous Commands

You can easily re-run a command from your history by using the ! symbol followed by the command number. For example, if the command you want to repeat is number 42 in the history list, you can type:

!42

This will execute the command exactly as you ran it before.

Using History for Efficiency

• Repeating the Last Command: If you want to run the very last command again, you can use !!:

  !!
  

  This is handy if you forgot to use sudo and want to rerun the command with it.

• Searching Your History: You can search for a previous command by typing Ctrl + r and then start typing part of the command. This will show you the most recent match from your history, which you can then execute by pressing Enter.

Summary

In this lesson, you learned how to navigate the filesystem using the pwd, ls, cd, clear and history commands, and you now understand the difference between absolute and relative paths. These are essential skills for working efficiently in the command line.

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