Chapter 2. Installing Python¶

Note¶

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

If you see some version information like the one shown above, then you have Python installed already.

However, if you get a message like this one:

$ python -V
bash: python: command not found

then, you don’t have Python installed. This is highly unlikely but possible.

In this case, you have two ways of installing Python on your system.

• Install the binary packages using the package management software that comes with your OS, such as yum in Fedora Linux, urpmi in Mandrake Linux, apt-get in Debian Linux, pkg_add in FreeBSD, etc. Note that you will need an internet connection to use this method. Alternatively, you can download the binaries from somewhere else and then copy to your PC and install it.
• You can compile Python from the source code and install it. The compilation instructions are provided at the website.

Caution¶

When you are given the option of unchecking any optional components, don’t uncheck any! Some of these components can be useful for you, especially IDLE.

An interesting fact is that about 70% of Python downloads are by Windows users. Of course, this doesn’t give the complete picture since almost all Linux users will have Python installed already on their systems by default.

Using Python in the Windows command line¶

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

For Windows 2000, XP, 2003 , click on Control Panel -> System -> Advanced -> Environment Variables. Click on the variable named PATH in the ‘System Variables’ section, then select Edit and add ;C:Python23 (without the quotes) to the end of what is already there. Of course, use the appropriate directory name.

For older versions of Windows, add the following line to the file C:AUTOEXEC.BAT : ‘PATH=%PATH%;C:Python23’ (without the quotes) and restart the system. For Windows NT, use the AUTOEXEC.NT file.