Chapter 1. Building and Installing SCons

This chapter will take you through the basic steps of installing SCons on your system, and building SCons if you don't have a pre-built package available (or simply prefer the flexibility of building it yourself). Before that, however, this chapter will also describe the basic steps involved in installing Python on your system, in case that is necessary. Fortunately, both SCons and Python are very easy to install on almost any system, and Python already comes installed on many systems.

1.1. Installing Python

Because SCons is written in Python, you need to have Python installed on your system to use SCons. Before you try to install Python, you should check to see if Python is already available on your system by typing python -V (capital 'V') or python --version at your system's command-line prompt. For Linux/Unix/MacOS/BSD type systems this looks like:

$ python -V
Python 3.7.1

Note to Windows users: there are a number of different ways Python can be installed or invoked on Windows, it is beyond the scope of this guide to unravel all of them. Many will have an additional program called the Python launcher (described, somewhat technically, in PEP 397): try using the command name py instead of python, if that is not available drop back to trying python.

C:\>py -V
Python 3.7.1

If Python is not installed on your system, or is not findable in the current search path, you will see an error message stating something like "command not found" (on UNIX or Linux) or "'python' is not recognized as an internal or external command, operable progam or batch file" (on Windows cmd). In that case, you need to either install Python or fix the search path before you can install SCons.

The canonical location for downloading Python from Python's own website is: There are useful system-specific entries on setup and usage to be found at:

For Linux systems, Python is almost certainly available as a supported package, possibly installed by default; this is often preferred over installing by other means, and is easier than installing from source code. Many such systems have separate packages for Python 2 and Python 3 - make sure the Python 3 package is installed, as the latest SCons requires it. Building from source may still be a useful option if you need a version that is not offered by the distribution you are using.

SCons will work with Python 3.5 or later. If you need to install Python and have a choice, we recommend using the most recent Python version available. Newer Pythons have significant improvements that help speed up the performance of SCons.