Gemini CLI Examples

Not sure where to get started with Gemini CLI? This document covers examples on how to use Gemini CLI for a variety of tasks.

Note: Results are examples intended to showcase potential use cases. Your results may vary.

Rename your photographs based on content

Scenario: You have a folder containing the following files:

photos/photo1.png
photos/photo2.png
photos/photo3.png

Give Gemini the following prompt:

Rename the photos in my "photos" directory based on their contents.

Result: Gemini will ask for permission to rename your files.

Select Yes, allow once. and your files will be renamed:

photos/yellow_flowers.png
photos/antique_dresser.png
photos/green_android_robot.png

Explain a repository by reading its code

Scenario: You want to understand how a popular open-source utility works by inspecting its code, not just its README.

Give Gemini CLI the following prompt:

Clone the 'chalk' repository from https://github.com/chalk/chalk, read its key source files, and explain how it works.

Result: Gemini will perform a sequence of actions to answer your request.

1. First, it will ask for permission to run git clone to download the repository.
2. Next, it will find the important source files and ask for permission to read them.
3. Finally, after analyzing the code, it will provide a summary.

Gemini CLI will return an explanation based on the actual source code:

The `chalk` library is a popular npm package for styling terminal output with colors. After analyzing the source code, here's how it works:

- **Core Functionality:** The main file sets up a chainable API. Each color or modifier (like `bold` or `italic`) is a getter that appends the corresponding ANSI escape code to an internal stack.

- **Chainable API:** When you call `chalk.red.bold('Hello')`, you are accessing getters. The `red` getter adds the red color code, and the `bold` getter adds the bold code.

- **Output Generation:** When the chain is treated as a string (e.g., in `console.log`), a final `toString()` method is called. This method joins all the stored ANSI codes, wraps them around the input string ('Hello'), and adds a reset code at the end. This produces the final, styled string that the terminal can render.

Combine two spreadsheets into one spreadsheet

Scenario: You have two .csv files: Revenue - 2023.csv and Revenue - 2024.csv. Each file contains monthly revenue figures, like so:

January,0
February,0
March,0
April,900
May,1000
June,1000
July,1200
August,1800
September,2000
October,2400
November,3400
December,2100

You want to combine these two .csv files into a single .csv file.

Give Gemini CLI the following prompt:

Combine the two .csv files into a single .csv file, with each year a different column.

Result: Gemini CLI will read each file and then ask for permission to write a new file. Provide your permission and Gemini CLI will provide the following .csv:

Month,2023,2024
January,0,1000
February,0,1200
March,0,2400
April,900,500
May,1000,800
June,1000,900
July,1200,1000
August,1800,400
September,2000,2000
October,2400,3400
November,3400,1800
December,2100,9000

Run unit tests

Scenario: You’ve written a simple login page. You wish to write unit tests to ensure that your login page has code coverage.

Give Gemini CLI the following prompt:

Write unit tests for Login.js.

Result: Gemini CLI will ask for permission to write a new file and create a test for your login page

import React from 'react';
import { render, fireEvent, waitFor } from '@testing-library/react';
import Login from './Login';

// Mock the API call for login
jest.mock('./api', () => ({
  login: jest.fn(),
}));

describe('Login component', () => {
  it('renders the login form correctly', () => {
    const { getByLabelText, getByText } = render(<Login />);

    expect(getByLabelText('Username')).toBeInTheDocument();
    expect(getByLabelText('Password')).toBeInTheDocument();
    expect(getByText('Login')).toBeInTheDocument();
  });

  it('shows an error message with invalid credentials', async () => {
    const { getByLabelText, getByText, findByText } = render(<Login />);
    const usernameInput = getByLabelText('Username');
    const passwordInput = getByLabelText('Password');
    const loginButton = getByText('Login');

    // Mock the API to return an error
    require('./api').login.mockRejectedValue(new Error('Invalid credentials'));

    fireEvent.change(usernameInput, { target: { value: 'testuser' } });
    fireEvent.change(passwordInput, { target: { value: 'wrongpassword' } });
    fireEvent.click(loginButton);

    const errorMessage = await findByText('Invalid credentials');
    expect(errorMessage).toBeInTheDocument();
  });

  it('logs in successfully with valid credentials', async () => {
    const onLoginSuccess = jest.fn();
    const { getByLabelText, getByText } = render(
      <Login onLoginSuccess={onLoginSuccess} />,
    );
    const usernameInput = getByLabelText('Username');
    const passwordInput = getByLabelText('Password');
    const loginButton = getByText('Login');

    // Mock the API to return a success message
    require('./api').login.mockResolvedValue({ success: true });

    fireEvent.change(usernameInput, { target: { value: 'testuser' } });
    fireEvent.change(passwordInput, { target: { value: 'correctpassword' } });
    fireEvent.click(loginButton);

    await waitFor(() => {
      expect(onLoginSuccess).toHaveBeenCalled();
    });
  });

  it('disables the submit button while submitting', async () => {
    const { getByLabelText, getByText } = render(<Login />);
    const usernameInput = getByLabelText('Username');
    const passwordInput = getByLabelText('Password');
    const loginButton = getByText('Login');

    // Mock the API to have a delay
    require('./api').login.mockImplementation(
      () =>
        new Promise((resolve) =>
          setTimeout(() => resolve({ success: true }), 1000),
        ),
    );

    fireEvent.change(usernameInput, { target: { value: 'testuser' } });
    fireEvent.change(passwordInput, { target: { value: 'correctpassword' } });
    fireEvent.click(loginButton);

    expect(loginButton).toBeDisabled();

    await waitFor(() => {
      expect(loginButton).not.toBeDisabled();
    });
  });
});