Introduction to Python Programming in Ubuntu Linux
By Veronica Henry on February 23, 2011
I began programming many years ago, and admittedly once I got into networking, turned away from my first love. But for those of you who would like to begin trying your hand at a new language, Python is excellent to start with. Supporters tout its low learning curve and elegant coding system.
Ubuntu makes starting easy, as it comes with a command line version pre-installed. In fact, the Ubuntu community develops many of its scripts and tools under Python. You can begin the process with either the command line version or the graphical Interactive Development Environment (IDLE).
Python Programming From the Command Line
Open a terminal window and type 'python' (without the quotes). This opens python in interactive mode.
While this mode is good for initial learning, you may prefer to use a text editor (like Gedit, Vim or Emacs) to write your code. As long as you save it with the .py extension, it can be executed in the terminal window.
Ready to write your first program? Many a road to programming excellence began with the old standby – the Hello World program. So that's where we'll begin.
At the prompt, type in print "Hello World!" (with the quotes) and hit enter. You'll see the command printed on the next line.
To run a script from the command line, type: python my_script.py. To exit the command line, type exit() or hit ctrl+d
Python Programming with IDLE
Can't imagine writing a long program from the command line? Me either. In that case, you can try IDLE. Open a terminal window and type: 'idle'. (without the quotes). You'll see the python graphical shell loaded.
To write a Python script, click on File > New Window. This will open a sort of Notepad type editor. Type in the following code:
#Have user input version and print response
name = raw_input("What Linux release do you use?")
print "I also like", name, " - Linux rules!"
Couple things going on here. The first 2 lines, preceded by the # sign are just comments. One of my earliest programming lessons was to always comment your work, not only for your own sanity, but for those who may need to edit the code after you. The third statement uses the input gathered from the raw_input function and assigns it to a variable, name. Finally, the print statement will return the result.
Save the file, with a .py extension, then click on Run > Run Module from the menu to run the program.
A Word of Caution
Many programming languages typically ignore whitespace – that is the spacing in your code. But in Python, improper use of spacing can generate syntax errors. As an organization nut of sorts, I can appreciate the simplicity and readability of properly aligned code, but for some this takes a bit of getting used to.
Python Programming Resources
Now that you have Python up and running, you'll undoubtedly want to move to on to a bit more complex programs. One of the best resources is the main Python website. Here are a few additional recommendations:
- The Python Tutorial
- The Python Wiki Beginner's Guide
- Screencast Presentation
- Python Essential Reference on Amazon
I hope you enjoyed this brief glimpse into Python. This is a language supported by a wide community and used by Google, NASA, Ubuntu and others. Give it a try for your next development project. Happy coding!