How to Install Flask on Kali Linux and Ubuntu 22.04

Running the Python Flask API framework

If you want a fast light weight API, then go for Flask. Flask, is a popular micro web framework written in Python, it is one of the tools that enables light weight API communication.

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Setting the Stage: Installing Python and Pip

Before installing Flask, we need to check some points. When using Flask, it’s crucial to have Python installed on your system, as Flask is a Python-based framework it needs Python to run.

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Kali Linux and Ubuntu 22.04, both being Linux distributions, usually have Python pre-installed. However, it’s always good to check and ensure that you have the latest versions installed. We will also be using ‘pip’, this is a Python package installer, that we will use to install Flask.

Verifying Python Installation

1. Open your terminal.
2. Type python --version or python3 --version.
3. If Python is installed, you’ll see the version number.

Installing or Updating Python

• If for some weird reason Python is not installed or you need a different version, use the command sudo apt-get install python3.

Installing Pip

1. Update your package list with sudo apt-get update.
2. Install pip using sudo apt-get install python3-pip.

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Installing Flask: The Main Event

Now that Python and pip are ready, installing Flask is straightforward.

1. Open your terminal.
2. Type pip install Flask.
3. This command downloads and installs Flask along with its dependencies.

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Verifying Flask Installation

After installing Flask, it’s a good practice to verify the installation.

1. Type python in the terminal to enter Python’s interactive mode.
2. Import Flask by typing from flask import Flask.
3. If no errors appear, Flask is installed correctly.

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Creating Your First Flask Application

Let’s put Flask to use by creating a simple web application.

Setting Up

1. Create a directory for your project.
2. Navigate to this directory in the terminal.
3. Create a new Python file, for example, app.py.

Writing the Application

1. Open app.py in a text editor.
2. Write the following basic Flask application:

from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'Hello, Cyberwarzone World!'

if __name__ == '__main__':
    app.run(debug=True)

This code creates a simple web server that returns “Hello, Cyberwarzone World!” when accessed.

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Running Your Flask Application

1. In the terminal, navigate to your project directory.
2. Run the application with python app.py.
3. Open a web browser and visit http://127.0.0.1:5000/.
4. You should see “Hello, Cyberwarzone World!” displayed.

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Troubleshooting Common Issues

While installing Flask is generally straightforward, you might encounter some issues. Common problems include:

Missing Dependencies

• Ensure all dependencies are installed with pip install -r requirements.txt if you have a requirements file.

Permission Issues

• Use sudo before commands if you encounter permission errors.

Python Version Conflicts

• Ensure you’re using the correct Python version. Use python3 instead of python if your system defaults to Python 2.