The source code of G'MIC is shared between several git repositories with public access. Accessing it via git ensures you get the latest code available, and will ease the source updates as well. Here are the instructions to compile G'MIC on a fresh installation of Debian (or Ubuntu). It should not be much harder for other distros. First you need to install all the required tools and libraries:

$ sudo apt-get install git build-essential libgimp2.0-dev libcv-dev libopencv-dev \ libhighgui-dev libcurl4-openssl-dev libfftw3-dev qt5-default qtbase5-dev

Then, get the G'MIC source from the different repositories:

$ git clone --depth=1 https://github.com/dtschump/gmic.git $ git clone --depth=1 https://github.com/c-koi/gmic-qt.git $ git clone --depth=1 https://github.com/c-koi/zart.git

You are now ready to compile all G'MIC interfaces: gmic (command-line tool), gmic_gimp_qt (plug-in for GIMP), gmic_krita_qt (plug-in for Krita), ZArt and libgmic ( G'MIC C++ library). Just pick your choice:

$ cd gmic/src $ make cli # Compile command-line interface $ make gimp # Compile plug-in for GIMP $ make krita # Compile plug-in for Krita $ make lib # Compile G'MIC library files $ make zart # Compile ZArt $ make all # Compile all of the G'MIC interfaces

and go out for a long drink (the compilation takes time).

Note that compiling issues (compiler segfault) may happen with older versions of g++ (4.8.1 and 4.8.2). If you encounter this kind of errors, you probably have to disable the support of OpenMP in G'MIC to make it work, by compiling it with:

$ make OPENMP_CFLAGS="" OPENMP_LIBS=""

Also, please remember that the source code in the git repository is constantly under development and may be a bit unstable, so do not hesitate to report bugs if you encounter any.