Javier Jimenez

Posted on Nov 29

Python on Ubuntu: Installation, Setup, and First Steps

#ubuntu #tutorial #beginners #python

I recommend viewing first – installation of Homebrew and asdf on Ubuntu (it's short, just 5 commands)

📘 Official Documentation

Python - Docs
Python - On DevDocs.io

⭐ Popular Frameworks (ordered from lower to higher learning curve)

Flask — Minimalist, simple.
FastAPI — Very fast, modern.
Django — Complete and structured.

🛠️ Installing Python on Ubuntu

sudo apt update
sudo apt install python3 python3-pip

🍺 Installation with Homebrew

brew install python

📦 Standard Package Manager (pip — included)

Check version:

pip3 --version

Install a package:

pip install <package>

🔧 Installation with ASDF

System dependencies

sudo apt update
sudo apt install -y build-essential libssl-dev zlib1g-dev \
libbz2-dev libreadline-dev libsqlite3-dev wget curl llvm \
libncursesw5-dev xz-utils tk-dev libxml2-dev libxmlsec1-dev

Install plugin + version

asdf plugin add python
asdf list-all python

# install different versions
asdf install python 3.12.2
asdf install python 2.7.18

# Set a global version
asdf global python 3.12.2

# Set a local version
# - Remember that a local version only affects the current directory that contains the .tool-versions file
asdf local python 2.7.18

Example: .tool-versions

python 3.12.2

📝▶️ Create and run a Python file

Create file:

touch hello.py

Content of hello.py

print("Hello World from Python!")

💻 Run locally:

python3 hello.py

🟦 Basic example in Python

🗂️🌐 Static file web server.

Note: Python already includes a basic built-in web server. You don’t need to install anything.

What it does:

Defines the name of the query parameter
Obtains the value of the query parameter from the URL
- strip_html_tags(text): Removes HTML tags leaving only inner content.
Renders the variable received in the query parameter inside the <H1> tag

📝 Create file: touch index.py

📦 Content of index.py

import re
import urllib.parse
from http.server import BaseHTTPRequestHandler, HTTPServer

class Handler(BaseHTTPRequestHandler):
    def do_GET(self):
        # Get parameters from the URL
        parsed = urllib.parse.urlparse(self.path)
        query = urllib.parse.parse_qs(parsed.query)

        username = query.get("username", ["invitado"])[0]
        username = strip_html_tags(username)

        # Response
        content = f"""
        <!DOCTYPE html>
        <html lang="es">
        <head>
            <meta charset="UTF-8">
            <title>Hola</title>
        </head>
        <body style="text-align:center">
            <h1>Hola, {username}</h1>
        </body>
        </html>
        """

        self.send_response(200)
        self.send_header("Content-type", "text/html")
        self.end_headers()
        self.wfile.write(content.encode("utf-8"))



def strip_html_tags(text):
    return re.sub(r"<[^>]+>", "", text)


# Start server
if __name__ == "__main__":
    server = HTTPServer(("localhost", 7000), Handler)
    print("Server running at http://localhost:7000")
    print("Test at http://localhost:7000?username=Homero")
    server.serve_forever()

▶️ Run the project / start the server

python3 index.py

👉 visit:
http://localhost:7000/?username=Homero

⚙️🧩 JSON REST API

What it does:

Reads data from a data.json file
Exposes one endpoint with that data
- A list of characters at /characters
- And the data of a character by id /characters/:id

Example file: data.json

[
  {
    "id": 1,
    "age": 39,
    "name": "Homer Tompson",
    "portrait_path": "https://cdn.thesimpsonsapi.com/500/character/1.webp"
  },
  {
    "id": 2,
    "age": 39,
    "name": "Marge Simpson",
    "portrait_path": "https://cdn.thesimpsonsapi.com/500/character/2.webp"
  }
]

📝 Create file: touch api.py

▶️ Content of the file: api.py

import json
from http.server import BaseHTTPRequestHandler, HTTPServer

# Load data.json
def load_characters():
    with open("data.json", "r", encoding="utf-8") as f:
        return json.load(f)


class MyHandler(BaseHTTPRequestHandler):

    def _send_json(self, data, status=200):
        self.send_response(status)
        self.send_header("Content-Type", "application/json")
        self.end_headers()
        self.wfile.write(json.dumps(data, ensure_ascii=False).encode("utf-8"))

    def do_GET(self):
        characters = load_characters()

        # GET /characters
        if self.path == "/characters":
            self._send_json(characters)
            return

        # GET /characters/:id
        if self.path.startswith("/characters/"):
            try:
                id_str = self.path.split("/")[2]
                char_id = int(id_str)
            except:
                self._send_json({"error": "Invalid ID"}, 400)
                return

            found = next((c for c in characters if c["id"] == char_id), None)

            if found:
                self._send_json(found)
                return
            else:
                self._send_json({"error": "Character not found"}, 404)
                return

        # If no route matches
        self._send_json({
            "error": "Route not found",
            "url_list": "http://localhost:7001/characters",
            "url_character": "http://localhost:7001/characters/1"
        }, 404)


if __name__ == "__main__":
    server = HTTPServer(("localhost", 7001), MyHandler)
    print("Server running at http://localhost:7001/characters")
    server.serve_forever()