9 unstable releases

0.5.4 Apr 6, 2021
0.5.3 Jul 14, 2020
0.5.2 Jan 9, 2020
0.5.1 May 22, 2019
0.2.0 Jul 18, 2017

#24 in Build Utils

37 downloads per month



Rust 3K SLoC // 0.1% comments Python 810 SLoC // 0.3% comments Shell 47 SLoC // 0.1% comments


Build Status Build status

Fac is a general-purpose build system inspired by make that utilizes ptrace to ensure that all dependences are enumerated and that all source files are added to a (git) repo. An important feature of fac is that it automatically handles dependencies, rather than either complaining about them or giving an incorrect build. Currently, fac only runs on linux systems, but on those systems it is incredibly easy to use!

  • Fac automatically tracks build dependencies in a way that is independent of programming language. You are only required to specify the minimum of dependencies for each rule, and fac works out the rest for you. If you fail to specify dependencies, fac should still build successfully after enough tries, provided your build rules fail when dependencies are missing (rather than simply producing wrong output). Once fac has successfully built your project, it knows the dependencies of each command, and subsequent builds in that source tree will be the same as if you had specified all dependencies and all output.

  • Fac supports parallel builds.

  • You are forced to write your configuration in a language of your own choice. (Or conversely, you are not forced to use a language of my choice, much less a custom-built language that I developed.)

  • Integrates with git, to keep you from forgetting to git add a file that is needed for the build.

To find out more about fac, including benchmarks and complete documentation, please visit the fac web page at:


Build and install

To build fac (assuming you have just cloned fac, and do not have an older version of fac) just run

cargo build

This should build fac on an x86-64 linux system that has rust installed. You may be able to use build-freebsd.sh to build on freebsd (but it is likely bit-rotted). You can then build an optimized version by running

target/debug/fac fac

To use fac, you can copy the fac binary into some location in your path.

Build dependencies and details

You need to have rust installed. In addition, fac requires both python2 and python3 (something to fix), and building the fac documentation (which is the default build target) requires sass and python-markdown.

For more detail on building fac, see the web page on building fac, which is also in the fac repository as web/building.md.


Fac is free software, and is licensed under the GNU General Public License, version 2 or later.


~87K SLoC