Introduction to the Command Line / Terminal

While many modern applications offer graphical user interfaces (GUIs) for interaction, the command line interface (CLI), often called the "terminal" or "shell," remains a fundamental tool for developers and increasingly for users interacting with more advanced software, including some local Large Language Model tools. Understanding its basics can significantly streamline the setup and management process described in this chapter.

Think of the command line as a text-based conversation with your computer. Instead of clicking icons and menus, you type specific commands, and the computer responds with text output or by performing an action. While it might seem intimidating initially, learning a few basic commands provides direct and powerful control over your system.

Why Bother with the Command Line?

For running local LLMs, familiarity with the command line is beneficial for several reasons:

1. Installation: Many LLM tools, frameworks (like llama.cpp), and supporting software (like Python and its packages) are installed or managed using command-line instructions. Tools like Ollama heavily rely on it for downloading and running models initially.
2. Direct Control: The command line often provides more direct access to program features and configurations than a GUI might expose.
3. Automation: Repetitive tasks can often be automated using simple command-line scripts.
4. Troubleshooting: Error messages and logs frequently appear in the terminal, providing important diagnostic information.
5. Ubiquity: It's a standard interface across different operating systems (Windows, macOS, Linux), making skills learned on one system often transferable to others.

Even if you plan to primarily use GUI tools like LM Studio, encountering command-line instructions during setup or troubleshooting is common.

Finding Your Terminal

Accessing the command line varies slightly depending on your operating system:

• Windows: You have a few options.
  • Command Prompt: Search for cmd or "Command Prompt" in the Start menu.
  • PowerShell: Search for PowerShell in the Start menu. It's a more modern and powerful alternative to Command Prompt.
  • Windows Terminal: A newer application from Microsoft (often pre-installed on Windows 11 or available from the Microsoft Store) that can host Command Prompt, PowerShell, and WSL (Windows Subsystem for Linux) sessions in tabs. This is often the recommended choice.
• macOS: The terminal application is simply called Terminal.
  • Go to Applications > Utilities folder and double-click Terminal.app.
  • Alternatively, use Spotlight search (Cmd + Space) and type Terminal, then press Enter.
• Linux: The name varies depending on the desktop environment, but common names include:
  • Terminal
  • Gnome Terminal (for GNOME environments)
  • Konsole (for KDE environments)
  • xterm (a more basic option)
  • You can usually find it in your applications menu under "System Tools" or similar, or by searching for "Terminal".

Once opened, you'll typically see a window with a blinking cursor next to something called a prompt. The prompt indicates the system is ready to receive your command. It often shows your username, the computer's name (hostname), and your current location (directory) in the file system, like C:\Users\YourName> on Windows or username@hostname:~$ on macOS/Linux.

Core Concepts: Commands, Arguments, and Paths

Interacting with the terminal involves typing a command and pressing Enter. Commands are simply the names of programs or built-in shell functions.

• Commands: The action you want to perform (e.g., cd, ls, ollama).
• Arguments: Additional information the command needs to operate on (e.g., a filename, a directory name, a URL).
• Options (or Flags/Switches): Modifiers that change how a command behaves, often starting with a hyphen (-) or double hyphen (--) (e.g., ls -l to show a detailed list).

One of the most fundamental concepts is navigating the file system. Your computer organizes files in directories (folders).

• pwd (Print Working Directory): On macOS and Linux, this command tells you your current directory location. (On Windows Command Prompt, the prompt itself usually shows the path, or you can type cd without arguments).
• ls (List): On macOS and Linux, this lists the files and directories within your current directory.
  • Example: ls
• dir (Directory): On Windows Command Prompt, this lists the files and directories.
  • Example: dir
• cd (Change Directory): This command allows you to move into a different directory. You provide the path to the directory as an argument.
  • Example (macOS/Linux): cd Documents (moves into the Documents subdirectory)
  • Example (Windows): cd Documents
  • Example (Moving up one level): cd .. (The .. represents the parent directory)

Let's try a quick example. Open your terminal and type the command to list files in your current directory (ls for macOS/Linux, dir for Windows), then press Enter.

# On macOS or Linux
ls

:: On Windows Command Prompt
dir

You should see a list of files and folders printed to the screen. Now try changing into a directory, for example, your Documents directory (assuming it exists directly within your current location):

# On macOS or Linux
cd Documents
pwd # Confirm your location changed
ls  # List files in Documents

:: On Windows Command Prompt
cd Documents
cd  # Confirm your location changed (prints the current path)
dir # List files in Documents

Don't worry if this seems unfamiliar. For this course, you won't need to become a command-line expert. We will provide the specific commands needed for tasks like installing Ollama or Python. The goal here is simply to introduce you to this essential tool and make those future steps less mysterious. Think of it as learning where the basic tools are in a workshop before starting a project.