Python is a versatile programming language that can be used for many
different programming projects. First published in 1991 with a name
inspired by the British comedy group Monty Python, the development team
wanted to make Python a language that was fun to use. Easy to set up,
and written in a relatively straightforward style with immediate
feedback on errors, Python is a great choice for beginners and
experienced developers alike. Python 3 is the most current version of
the language and is considered to be the future of Python.
This tutorial will guide you through installing Python 3 on your local
Linux machine and setting up a programming environment via the command
line. This tutorial will explicitly cover the installation procedures
for Ubuntu 16.04, but the general principles apply to any other
distribution of Debian Linux.
Prerequisites
You will need a computer with Ubuntu 16.04 installed, as well as have
administrative access to that machine and an internet connection.
Step 1 — Setting Up Python 3
On Ubuntu 16.04, you can find the Terminal application by clicking on
the Ubuntu icon in the upper-left hand corner of your screen and typing
“terminal” into the search bar. Click on the Terminal application icon
to open it. Alternatively, you can hit the
CTRL,
ALT, and
T keys on your keyboard at the same time to open the Terminal application automatically.
Ubuntu 16.04 ships with both Python 3 and Python 2 pre-installed. To
make sure that our versions are up-to-date, let’s update and upgrade the
system with
apt-get:
- sudo apt-get update
- sudo apt-get -y upgrade
The
-y flag will confirm that we are agreeing for all
items to be installed, but depending on your version of Linux, you may
need to confirm additional prompts as your system updates and upgrades.
Once the process is complete, we can check the version of Python 3 that is installed in the system by typing:
You will receive output in the terminal window that will let you know
the version number. The version number may vary, but it will look
similar to this:
Output
Python 3.5.2
To manage software packages for Python, let’s install
pip:
- sudo apt-get install -y python3-pip
A tool for use with Python,
pip installs and manages
programming packages we may want to use in our development projects.
You can install Python packages by typing:
- pip3 install package_name
Here,
package_name can
refer to any Python package or library, such as Django for web
development or NumPy for scientific computing. So if you would like to
install NumPy, you can do so with the command
pip3 install numpy.
There are a few more packages and development tools to install to
ensure that we have a robust set-up for our programming environment:
- sudo apt-get install build-essential libssl-dev libffi-dev python-dev
Once Python is set up, and pip and other tools are installed, we can set up a virtual environment for our development projects.
Step 2 — Setting Up a Virtual Environment
Virtual environments enable you to have an isolated space on your
computer for Python projects, ensuring that each of your projects can
have its own set of dependencies that won’t disrupt any of your other
projects.
We need to first install the
venv module, part of the standard Python 3 library, so that we can create virtual environments. Let’s install venv by typing:
- sudo apt-get install -y python3-venv
With this installed, we are ready to create environments. Let’s
choose which directory we would like to put our Python programming
environments in, or we can create a new directory with
mkdir, as in:
- mkdir environments
- cd environments
Once you are in the directory where you would like the environments
to live, you can create an environment by running the following command:
Essentially, this sets up a new directory that contains a few items which we can view with the
ls command:
Output
bin include lib lib64 pyvenv.cfg share
To use this environment, you need to activate it, which you can do by
typing the following command that calls the activate script:
- source my_env/bin/activate
Your prompt will now be prefixed with the name of your environment, in this case it is called
my_env.
Your prefix may look somewhat different, but the name of your
environment in parentheses should be the first thing you see on your
line:
This prefix lets us know that the environment
my_env
is currently active, meaning that when we create programs here they
will use only this particular environment’s settings and packages.
Step 3 — Creating a Simple Program
Now that we have our virtual environment set up, let’s create a
simple “Hello, World!” program. This will make sure that our environment
is working and gives us the opportunity to become more familiar with
Python if we aren’t already.
To do this, we’ll open up a command-line text editor such as nano and create a new file:
Once the text file opens up in the terminal window we’ll type out our program:
print("Hello, World!")
Exit nano by typing the
control and
x keys, and when prompted to save the file press
y.
Once you exit out of nano and return to your shell, let’s run the program:
The hello.py program that you just created should cause your terminal to produce the following output:
Output
Hello, World!
To leave the environment, simply type the command
deactivate and you will return to your original directory.
