Installation Guide

This is the Felix installation guide.

Linux: Ubuntu

Install Pre-requisites

The first step is to install the pre-requisites. The following list may not be complete. From command line or other tool install packages:

sudo apt-get install binutils
sudo apt-get install make
sudo apt-get install git
sudo apt-get install g++
sudo apt-get install python3
sudo apt-get install ocaml-native-compilers

These are optional components which provide graphics for the Felix GUI using Simple Direct Media Layer, version 2:

sudo apt-get install libsdl2-dev
sudo apt-get install libsdl2-ttf-dev
sudo apt-get install libsdl2-image-dev
sudo apt-get install libsdl2-gfx-dev

There are many other optional packages for which there is some level of support or interest. These include, without their apt-name at the momen (sorry, please help!):

  • gmp: gnu big number library
  • gmp++: C++ wrapper for gmp
  • gsl: gnu scientific library
  • botan: Crypto library
  • icu: unicode library

Clone Felix

You first need to configure git, please see git docs. Then for a user without write access to the Felix repository, make a workspace directory in which the Felix repository directory will be created and cd into it. Now grab a copy of Felix:

git clone

Build Felix

Now you have to go into the repository clone and build Felix:

cd felix
. buildscript/

What happens is that a build system called fbuild which is a Python program, will build a bootstrap version of Felix first.

Then, the bootstrap Felix will be used to build Felix again, this time using Felix own build tools, which are written in Felix.

Finally, a four test suites run. The first is a small number of bad tests that are supposed to all fail, ignore it.

Then the main regression test suite runs. Most of these tests should pass, or there’s a bug, but as long as most pass, don’t worry (at least, not yet!)

Then some tutorial examples are run as tests. Again, most should pass but don’t worry about one or two fails.

Finally, some optional tests run, which exercise optional packages. Most of these are graphics and GUI tests and they WILL fail on Ubuntu. We will fix that in a moment!


Felix does not have to be installed to work. I recommend you do not install it, at least not yet. Installation is for enterprise users, rather than personal users.

The reason is that upgrades are frequent: Felix is typically upgraded every day. Rebuilding Felix is easy, but it is a pain reinstalling it all the time, it is better initially to run it in place. But here is how you would install it:

sudo mkdir -p /usr/local/lib
sudo mkdir -p /usr/local/bin
sudo make install

This will put most of the Felix system in /usr/local/lib/felix/felix-version where felix-version is the version of Felix you’re installing. You can install many versions of Felix all at once.

The install process also puts the flx command into /usr/local/bin. This will overwrite any previous flx. For the installed Felix to work at all you will need to setup the PATH variable:

export PATH=/usr/local/bin:$PATH

The best place to do this is in your $HOME/.profile, if it is not set already.

For full plugin and dynamic library support, you will also need to set LD_LIBRARY_PATH. Normally, flx sets this for you, but if you want to run Felix built executables directly as standalone programs, and you want to link to Felix shared libraries, including plugins, then the system linker has to find the libraries so you will also need this:

export LD_LIBRARY_PATH=/usr/local/lib/felix/felix-version:$LD_LIBRARY_PATH

Felix does not put its shared libraries in the usual place, directly in a /usr/lib or /usr/local/lib directory. This is deliberate. You need to be able to delete a Felix version, or all of Felix easily, and for this reason almost everything lives under master directory /usr/local/lib/felix and subdirectory felix-version, the main exception being the flx program, which is copied to /usr/local/bin.

Running in Place

This option is prefered over installing Felix at the moment, although it is a little tricker to set up, it makes it very much easier to upgrade Felix.

After you have built Felix, you can use it in place, without installing it. First you need to do this: make sure you are still in the Felix directory, be very careful to use the correct quotation marks as indicated below!!

echo `export PATH=$PWD/build/release/host/bin:$PATH` >> $HOME/.profile
mkdir -p $HOME/.felix/config
echo "FLX_INSTALL_DIR: $PWD/build/release" >$HOME/.felix/config/felix.fpc

The flx executable looks to see if the file $HOME/.felix/config/felix.fpc exists, and if it does, it will set the variables seen in that file. You can also set the environment variable FLX_INSTALL_DIR in the Linux environment by adding this command to your $HOME/.profile:

export FLX_INSTALL_DIR=$PWD/build/release

where $PWD has to be replaced by the absolute path of the repository, and then the command above should be put into your $HOME/.profile. I personally use the first method.

Installing to an Alternate Location

PREFIX needs to be set and exported to the location to install, otherwise it defaults to /usr/local, e.g.:

export PREFIX=/home/user/local

If you want to install it to the same location as previously (or to the configured location) you can just do:


Test it

This should work now:

flx hello.flx