.. include:: ../images.rst


ROOT installation
~~~~~~~~~~~~~~~~~~~~~

An object oriented framework for large scale data analysis

git repository : http://github.com/root-project/root.git

home site : https://root.cern.ch/

.. note::
   For the recommended **CMake** build (see :doc:`cwb`), the easiest way to
   get ROOT is via conda-forge:

   .. code-block:: bash

       conda install -c conda-forge root_base

   See the `library README <https://gitlab.com/gwburst/public/library/-/blob/public/README.md>`__
   for the currently supported ROOT versions (CI-tested: 6.30, 6.32, 6.34;
   additionally validated on **6.36**, the recommended target) and why ROOT
   6.40 is not yet supported.

For the **traditional Makefile** build, ROOT is instead built from source.
A version compatible with the CMake build's supported range, e.g. 6.36, is
suggested:

.. code-block:: bash

    #  clone root from git repository
    git clone http://github.com/root-project/root.git
    # checkout a specific version
    git checkout -b v6-36-06 v6-36-06
    # create a building directory
    mkdir -p root/build_root; cd  root/build_root
    # configure root
    cmake .. -DCMAKE_INSTALL_PREFIX:PATH=${HOME}/SOFT/ROOT/root_v6-36-06;
    # build
    cmake --build . --verbose --parallel ${CPU_COUNT}
    # install
    cmake --build . --verbose --parallel ${CPU_COUNT} --target install

For older, pre-existing CIT/VirtualBox setups, a precompiled ROOT 6.24.06
binary is also still available (legacy, no longer the suggested version):

.. image:: https://img.shields.io/badge/CentOS Cern 7 gcc4.8-download-blue.svg
   :target: https://root.cern.ch/download/root_v6.24.06.Linux-centos7-x86_64-gcc4.8.tar.gz

.. code-block:: bash

    cd $HOME_LIBS/ROOT
    wget https://root.cern.ch/download/root_v6.24.06.Linux-centos7-x86_64-gcc4.8.tar.gz
    tar xf root_v6.24.06.Linux-centos7-x86_64-gcc4.8.tar.gz
    mv root root_v6.24.06

.. note::
   For the traditional Makefile build, set the ROOT_VERSION environment
   variable in the watenv script.