Ubuntu – How to install Python IDLE

In the terminal run

sudo apt-get install idle3

(The right package name for IDLE with Python 3 is idle3 I think you can check it Software Center.)

If you are not sure about the name of a package you can run apt-cache search <string> which will look for packages which contains <string> in their names or descriptions.

Edit:

To use Python 3.3 in 12.04:

• You can try bootstrapping Raring/Saucy. See pbuilder HowTo. (Kind of complicated, but very good.)
• Or you can try installing Debian+Xfce testing or Xubuntu 13.04 in VirtualBox. (This depends on your system capabilities, that's why I recommend a lightweight DE.)
• You can even try building Python 3.3 from source and installing it in a folder of your preference, but don't know how much effort this would take.

Of course, the most 'trivial' alternative would be to upgrade from Precise to Raring. Specially good if you can backup your important data and do a clean install.

Python 3.5.1 is installed on Ubuntu 16.04 by default. You can verify that by running the command python3 --version in a terminal.

Now, IDLE for Python 3 is in the package idle3 and part of the default Python distribution but it's not installed on Ubuntu by default. You can do so with Software Center or your favourite package manager. On the command-line you can run:

sudo apt-get install idle3

If that gives you an error as you say in the comments, please edit your question with the "edit" link below it to include the error messages verbatim (and send me a message in the comments to notify me of the change), or ask a new question with the same information.