Ollama day-1 guide

After installing Ollama, quickly start using local AI models on Linux or macOS with a few lean commands in the terminal.

Installing and First Use

  • Install via shell: curl https://ollama.ai/install.sh | sh This sets up Ollama on Linux/Mac.
  • Run your first model: ollama run llama3.2:3b This downloads and runs the selected model, opening an interactive chat.

Quick Reference Table

Command Function
ollama run model_name Run model in chat
ollama list See downloaded models
ollama pull model_name Download a new model
ollama rm model_name Delete a model
ollama show model_name Model details
ollama cp src dest Copy model to new name
/bye (during run) Exit chat session
/set system "prompt" (during run) Set one-off system prompt

Customizing an Ollama Model

To customize an Ollama model—editing it, setting a system prompt, and saving as a new model—use the following lean workflow and command examples.

  1. Export the Current Modelfile

    Use the original model as a template:

    ollama show llama3 --modelfile > MyModelfile

    This creates a file named MyModelfile with the current model's configuration.

  2. Edit the Modelfile and Set a System Prompt

    Open MyModelfile in any text editor (e.g., nano, vim, code):

    nano MyModelfile

    In the file, adjust parameters and add/change a system prompt. For example:

FROM llama3
PARAMETER temperature 0.7
SYSTEM """
You are a Linux and Bash expert. Only provide concise, correct code with clear explanations.
"""

  1. Build Your Custom Model

    Create a new model from the customized Modelfile:

    ollama create bash-expert -f MyModelfile

    This saves the tailored model under the name bash-expert.

  2. Run the Customized Model

    ollama run bash-expert

    The model will now always respond using your provided system prompt.

In-Session Quick System Prompt (One-off)

During an interactive chat:

/set system "You are a SQL expert. Explain queries before showing code."

Applies the system prompt for just that session.

This process lets you efficiently create, guide, and save your own specialized Ollama models for targeted tasks.