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CSE 142: Computer Programming I, Summer 2008

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Installing Python

Like Java, you will need at most only two pieces of software: the Python environment and some text editor. Depending on your operating system, you'll use different instructions to install Python.


If you encounter problems trying to set up Python, contact Marty for help and suggestions.


Windows does not come with Python pre-installed, so you will have to download and install it.

Step 1. Install Python

Python v2.5.2 Installer

Click the link above to download the Python installer. Once downloaded, run the program to install Python.

Step 2. Run The IDLE Editor

IDLE is an interpreter/editor combo called found under "Start -> Programs -> Python 2.5.2 -> IDLE (Python GUI)". To create a new Python script, go to "File -> New Window" (CTRL+N). Here you can type out your Python code, save it, and then run it by selecting "Run -> Run Module" (F5). A benefit of the IDLE environment is that you can test Python commands in the Python Shell window ("Run -> Python Shell"), which contains the Python interactive interpreter.

To use the Python interpreter alone, run "Start -> Programs -> Python 2.5.2 -> Python (command line)". Here you can type Python commands into the window interactively.

Mac OS X

Python comes pre-installed on Macs. However, it is often an older version, and it doesn't come bundled with an editor. We recommend one of two choices:

  1. Downloading and installing the newest version of Python from http://www.python.org/download/mac/ . This will include the IDLE editor.
  2. Or, just downloading some other code editor and using your Mac's existing older version of Python.

If you choose route 1, instructions are in the link provided. If you choose route 2, we recommend installing the Smultron text editor:

Step 1. Install Smultron

Smultron Homepage

First, go to the Smultron Homepage and download the Latest Version from the Download section in the top right.

Step 2. Configure Smultron for Python

Although Smultron will work fine without configuration, a single configuration option will make life a little easier.

Go to "Tools -> Handle Commands -> Show Commands Window" (⌘B) and select "Other" under the Collections column. Next, click "New Command" in the top right. For a name, put "Run Python Script". In the box below, type

/usr/bin/env python %%p
. Optionally, double-click the shortcut field to create a shortcut to run your script. If everything was done correctly, it should look like this screenshot.

Step 3. Using Your Editor

Smultron is easy to use. First, create a new document (⌘N). Next, save your empty document (⌘S) as a .py file -- for example, "greeneggs.py". Finally, type your Python code as you normally would and it will show up with syntax highlighting.

To run your Python code, select "Tools -> Commands -> Other -> Run Python Script", or optionally use your shortcut keybind if you made one in the previous step.

Step 4. Using the Python Interpreter

To use the Python Interpreter, open Terminal and type

to start it. Terminal is located in "Applications -> Utilities -> Terminal".


Chances are, if you're using a Linux distribution you probably have Python already. To check, open a Terminal (aka Command Line) and type

. If you already have Python installed, this will pull up a Python Interpreter; otherwise, follow the instructions to get Python on this page.

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