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Fbuild Build System

MASTER BRANCH: AppVeyor Travis

DEV BRANCH: AppVeyor Travis


Fbuild is a build system designed for configuring and compiling both small and large projects. It has extensive feature list:

  • Linux, Apple, and Windows support
  • Supports compiling C, C++, OCaml, Java, Scala, GHC, and Felix
  • Extensive configuration detection for the C and C++ standard library, posix, and more
  • Parallel compilation
  • Cross compiling
  • Digest-based tracking of file changes
  • Full Python scriptability
  • Easy to extend
  • Pretty output
  • ... and it is quite fast, too

WARNING: MinGW is currently NOT supported. It should be, but things quickly went haywire. You can try it still, but note that building shared libraries does not work. Using Visual C++ works as expected.

Downloading and Installation

Fbuild is hosted and developed on Github. It requires Python 3. As the last Fbuild release was a very long time ago, your best bet is to get Fbuild straight from git:

$ git clone

If you want the bleeding-edge development version, run:

$ git clone -b dev

To install, run:

$ cd fbuild
$ python3 install


NOTE: There are some incomplete docs at ReadTheDocs.

Fbuild has extensive support for advanced build systems, but this doesn't complicate simple projects. Here is the classic "Hello World" example, written in a C file named helloworld.c:

#include <stdio.h>
int main() {
    printf("hello world!\n");
    return 0;

Along side of it, we will create a Python 3 file named, which will drive the compilation. We'll step through each line in a moment:


def build(ctx):
    builder =
    exe = builder.build_exe('helloworld', ['helloworld.c'])

    ctx.logger.log(' * running ' + exe)

As you can see, it's a pretty compact Python script. To compile it, if you installed Fbuild, simply run fbuild in the same directory as the Otherwise, you can run fbuild-light out of the Fbuild distribution, which doesn't require installation. This is what you'll see:

$ fbuild  # or $FBUILD_DIR/fbuild-light
determining platform     : {'bsd', 'darwin', 'macosx', 'posix'}
looking for program gcc   : ok /usr/bin/gcc
checking gcc              : ok
looking for program ar    : ok /usr/bin/ar
looking for program ranlib : ok /usr/bin/ranlib
checking if gcc can make objects : ok
checking if gcc can make libraries : ok
checking if gcc can make exes      : ok
checking if gcc can link lib to exe : ok
 * gcc                              : helloworld.c -> build/helloworld.o
 * gcc                              : build/helloworld.o -> build/helloworld
 * running build/helloworld
hello world!

Broken down, Fbuild:

  • automatically determined that I'm on a Apple machine
  • configured gcc for our C builder
  • tested that the C builder worked
  • compiled our code
  • and finally, ran the program

Now lets go through the

def main(ctx):

Fbuild is written as a Python library with the fbuild script as a simple driver in order start up and stop the build. The default entry point is a function called build. If you run fbuild without any arguments or with fbuild build, it will call this function. You can also create your own entry points with the module, which is described further on.

builder =

Next we have to make a C builder. Since pretty much each platform has it's own C compiler, Fbuild provides a mechanism to guess the platform's preferred one. creates a C builder that is capable of creating static libraries. You can also use if you want to create dynamically loadable libraries. In this case though, we're just creating an executable, so it doesn't matter which function we use.

exe = builder.build_exe('helloworld', ['helloworld.c'])

Now that we've got a builder, we can compile our binary. The first argument is the name of the executable, and the second is a list of input sources. There are a large amount of other options available. The most important are:

Argument Description
includes a list of directories to add to the include search path
libs a list of libraries to link in
libpaths a list of directories to add to the library search path
external_libs a list of libraries Fbuild should not track modification
macros a list of string macros
debug a boolean to enable debug builds
optimize a boolean to enable optimized builds
cflags a list of arbitrary arguments to pass to the compiler
lflags a list of arbitrary arguments to pass to the linker

These arguments can also be passed to if you want them to apply to everything built by the builder.

ctx.logger.log(' * running ' + exe)

Finally, we'll execute the command we just compiled. We use ctx.logger.log so that the message will be logged into the Fbuild log file, normally found in build/fbuild.log. To run the command we use ctx.execute, which is a wrapper around the subprocess module that also writes the command's output to the log file.

In comparison, this is an equivalent Makefile, written to use gcc:

exe = helloworld
srcs = helloworld.c
objs = $(srcs:%.c=%.o)

all: helloworld

helloworld: $(objs)
    gcc -o $@ $<

%.o: %.c
    gcc -c -o $@ $<

As you can see, Fbuild's driver script is about half the size and does much more.

Unit Tests

To run the unit tests:

$ cd tests
$ python3


If you run into any problems, don't hesitate to ask a question on the fbuild mailing list.


A cross platform, high performant caching build system




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