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Python : Installation

Installation

When we refer to “Python 3” in this book, we will be referring to any version of Python equal to or greater than 3.3.2.

Installation on Windows

Visit http://www.python.org/download/ and download the latest version. The installation is just like any other Windows-based software.

Caution: When you are given the option of unchecking any “optional” components, don’t uncheck any.

DOS Prompt

If you want to be able to use Python from the Windows command line i.e. the DOS prompt, then you need to set the PATH variable appropriately.

For Windows 2000, XP, 2003 , click on Control PanelSystemAdvancedEnvironment Variables. Click on the variable named PATH in the ‘System Variables’ section, then select Edit and add ;C:\Python33 (please verify that this folder exists, it will be different for newer versions of Python) to the end of what is already there. Of course, use the appropriate directory name.

For older versions of Windows, open the file C:\AUTOEXEC.BAT and add the line ‘PATH=%PATH%;C:\Python33‘ (without the quotes) and restart the system. For Windows NT, use the AUTOEXEC.NT file.

For Windows Vista:

  1. Click Start and choose Control Panel
  2. Click System, on the right you’ll see “View basic information about your computer”
  3. On the left is a list of tasks, the last of which is “Advanced system settings.” Click that.
  4. The Advanced tab of the System Properties dialog box is shown. Click the Environment Variables button on the bottom right.
  5. In the lower box titled “System Variables” scroll down to Path and click the Edit button.
  6. Change your path as need be.
  7. Restart your system. Vista didn’t pick up the system path environment variable change until I restarted.

For Windows 7:

  1. Right click on Computer from your desktop and select properties or Click Start and choose Control Panel — System and Security — System. Click on Advanced system settings on the left and then click on the Advanced tab. At the bottom click on Environment Variables and under System variables, look for the PATH variable, select and then press Edit.
  2. Go to the end of the line under Variable value and append ;C:\Python33.
  3. If the value was %SystemRoot%\system32; It will now become %SystemRoot%\system32;C:\Python33
  4. Click OK and you are done. No restart is required.

Running Python prompt on Windows

For Windows users, you can run the interpreter in the command line if you have set the PATH variable appropriately.

To open the terminal in Windows, click the start button and click ‘Run’. In the dialog box, type cmd and press enter key.

Then, type python and ensure there are no errors.

Installation on Mac OS X

For Mac OS X users, open the terminal by pressing Command+Space keys (to open Spotlight search), type Terminal and press enter key.

Install Homebrew by running:

ruby -e "$(curl -fsSkL raw.github.com/mxcl/homebrew/go)"

Then install Python 3 using:

brew install python3

Now, run python3 and ensure there are no errors.

Installation on GNU/Linux

For GNU/Linux users, open the terminal by opening the Terminal application or by pressing Alt + F2 and entering gnome-terminal. If that doesn’t work, please refer the documentation or forums of your particular GNU/Linux distribution.

Next, we have to install the python3 package. For example, on Ubuntu, you can use sudo apt-get install python3. Please check the documentation or forums of the GNU/Linux distribution that you have installed for the correct package manager command to run.

Once you have finished the installation, run the python3 and ensure there are no errors.

You can see the version of Python on the screen by running:

$ python3 -V
Python 3.3.2

Note: $ is the prompt of the shell. It will be different for you depending on the settings of the operating system on your computer, hence I will indicate the prompt by just the $ symbol.

Default in new versions of your distribution?: Upcoming GNU/Linux distributions such as Ubuntu 14.04 LTS are making Python 3 the default version, so check if it is already installed.

Summary

From now on, we will assume that you have Python 3 installed on your system.

Next, we will write our first Python 3 program.


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