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.
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
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.
git clone to download the repository.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.
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
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();
});
});
});