Getting Started with SCons

An Alternative build system to make

SCons is a next-generation make utility that is much easier to configure and use than make. Many developers find make syntax not just difficult to get into but quite ugly. I've wasted more than a few hours trying to get a make file just right. Once you've learned it, it's okay, but it has a bit of a steepish learning curve.

So that's why SCons was devised; it's a better make and considerably easier to use. It even tries to figure out what compiler etc is needed and then supplies the right parameters. If you program in C or C++ on Linux or Windows then you should definitely check SCons.

Installing SCons

To install SCons you need to have Python already installed. Most of this article is about installing it under Windows. If you are using Linux then most likely you'll have Python already.

If you have Windows you can check if you already have it; some packages might have installed it already. First get a command line. Click the start button, (on XP click Run), then type cmd and from the command line type python -V. It should say something like Python 2.7.2. Any version 2.4 or higher is ok for SCons.

If you haven't got Python then you need to visit the Python download page and install 2.7.2. Currently, SCons does not support Python 3 so 2.7.2 is the latest (and final) 2 version and the best one to use. However, that may change in the future so check the SCons requirements in Chapter 1 of the ‚ÄčSCons user guide.

  • Want to Learn Python? Check out our Python site!

Follow the instructions for installing SCons. It's not complicated. However when you run the installer, if it's under Vista/Windows 7 make sure you run the scons..win32.exe as administrator. You do this by browsing to the file in Windows Explorer and right click then Run As Administrator. When I first ran it, it wasn't able to create registry keys, so that's why you need to be Administrator.

Once it's installed then, assuming you have any of Microsoft Visual C++ (Express is ok), MinGW tool chain, Intel Compiler or the PharLap ETS compiler already installed, SCons should be able to find and use your compiler.

Using SCons

As a first example, save the code below out as HelloWorld.c.

int main(int arcg,char * argv[])
printf("Hello, world!\n");

Then create a file called SConstruct in the same location and edit it so it has this line below in it. If you save the HelloWorld.c with a different filename, make sure that the name inside the quotes matches.


Now type scons at the command line (in the same place as HelloWorld.c and SConstruct) and you should see this:

scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
cl /FoHelloWorld.obj /c HelloWorld.c /nologo
link /nologo /OUT:HelloWorld.exe HelloWorld.obj
scons: done building targets.

This built a HelloWorld.exe which when run produces the expected output: C:\cplus\blog>HelloWorld
Hello, world!

Notes on SCons

The online documentation is very good for getting you started. You can refer to the terse single file man (manual) or the friendlier more verbose SCons Users Guide.

SCons makes it easy to remove unwanted files from the compilation just add the -c or -clean parameter.

scons -c

This gets rid of HelloWorld.obj and the HelloWorld.exe file.

SCons is cross platform, and while this article has about getting started on Windows, SCons comes prepackaged for Red Hat(RPM) or Debian systems. If you have another flavor of Linux, then the SCons guide gives instructions for building SCons on any system. It's open source at its best.

SCons SConstruct files are Python scripts so if you know Python, then you'll have no probs. But even if you don't, you only need to learn a small amount of Python to get the best out of it. Two things you should remember, though:

  1. Comments start with #
  2. You can add print messages with print("Some Text")

Not for .NET but...

Note that SCons is only for non .NET, so it can't build .NET code unless you learn SCons a bit more and create a specific builder as described on this SCons Wiki page.

What do I do next?

Go and read the User Guide. As I said, it's very well written and easy to get into and start playing with SCons.