Building ROOT

Main Page -> Control & Readout Software Documentation and Howto's -> Building ROOT

In the pCT project we need to use a version of ROOT which is compiled with c++17 in order to build packages with ROOT dependencies with c++17 standard. .

ROOT implements a custom adaptor to std::string_view if not compiled with c++17 and this conflicts with the real one if a packages uses c++17 standard and ROOT libraries/includes.

<syntaxhighlight lang="bash"> sudo yum install git cmake gcc-c++ gcc binutils \ libX11-devel libXpm-devel libXft-devel libXext-devel \ gcc-gfortran openssl-devel pcre-devel \ mesa-libGL-devel mesa-libGLU-devel glew-devel ftgl-devel mysql-devel \ fftw-devel cfitsio-devel graphviz-devel \ avahi-compat-libdns_sd-devel libldap-dev python3-devel \ libxml2-devel gsl-static gsl-devel \ libAfterImage libAfterImage-devel \ centos-release-scl devtoolset-8

sudo python3 -m pip install numpy

1. clone the repository and select version

git clone http://github.com/root-project/root.git cd root git checkout v6-20-00-rc1

1. choose a build directory

mkdir build_root; cd build_root

scl enable devtoolset-8 bash

1. configure: choose install target, on the lab machine we need to disable asimage for some reason
2. the important flag is the C++ standard

cmake3 -DCMAKE_INSTALL_PREFIX=/opt/root -DCMAKE_CXX_STANDARD=17 -DPYTHON_EXECUTABLE=/usr/bin/python3 ../

1. build and install

sudo cmake3 --build . --target install -- -j4

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Remember to add root details to your environment, e.g. /etc/bashrc: (LD_LIBRARY_PATH and PYTHONPATH must BOTH be set for pyroot to work)

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export ROOTSYS=/opt/root source $ROOTSYS/bin/thisroot.sh

export LD_LIBRARY_PATH=/opt/root/lib:$LD_LIBRARY_PATH

export PYTHONPATH=/opt/root/lib:$PYTHONPATH

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Installation for pCT-Online on Ubuntu systems

Install dependencies: sudo apt-get install dpkg-dev binutils libx11-dev libxpm-dev libxft-dev libxext-dev libpng-dev libjpeg-dev

If you lack certain dependencies install everything listed in the above documentation before the "# clone the repository and select version" line. Disregard this if your installation works.

In a terminal move to the folder where you want to install ROOT.

Follow these commands:

• git clone http://github.com/root-project/root.git
• cd root
• git checkout v6-20-00-rc1 (other releases might also work) IMPORTANT!
• cd ..
• mkdir build_root (root can not be built inside the source root folder!! The rest of the steps will assume the build_root folder is in the same directory as the source root folder)
• cd build_root
• cmake ../root -DCMAKECXXSTANDARD=17 -DPYTHONEXECUTABLE=/usr/bin/python3
• make -jN (N is the number of CPU cores available for building, use N=4 if you don’t know)
• source bin/thisroot.sh