prereq-centos7.md

aliBuild Prerequisites for CentOS 7

For ALICE O2, CERN CentOS 7 (CC7)is the officialy supported target platform. Since CC7 is CentOS 7 with additional CERN packages, instructions apply to vanilla CentOS 7 as well.

Install or Upgrade the Required Packages

With root permissions, i.e. sudo or as root install the prerequisites using:

cat << EOF > /etc/yum.repos.d/alice-system-deps.repo
[alice-system-deps]
name=alice-system-deps
baseurl=https://s3.cern.ch/swift/v1/alibuild-repo/RPMS/o2-full-deps_x86-64/
enabled=1
gpgcheck=0
EOF
yum update -y
yum install -y alice-o2-full-deps

Python and pip

AliBuild, our build tool, is installed via the python Package manager pip. In case

pip3 show pip

returns command not found or similar, install pip with root permissions, i.e. sudo or as root:

yum install -y python3-pip
pip3 install --upgrade pip

Get or Update Developer Toolset 7

We require a more recent set of compilers than shipped by the OS. They can be obtained via Softawre Collections.

The only supported Developer Toolset for ALICE software is devtoolset-7.

With root permissions, i.e. sudo or as root enable software collections:

yum install -y centos-release-scl
yum-config-manager --enable rhel-server-rhscl-7-rpms

Then, still with root permissions install compilers and developer tools via:

yum install -y devtoolset-7

By design these tools do not replace the standard tools shipped by the system and have to be enabled explicitly for every new shell session you open:

source scl_source enable devtoolset-7

If desired so, the above line can be added to your ~/.bashrc or ~/.bash_profile, so that tools shipped via devtoolset are automatically available in every shell. However beware that in some special cases that this might have undesired side effects.

You can check if you are running the correct version of GCC with:

gcc --version

It should report GCC v7.3.1.

You are now ready for installing aliBuild and start building ALICE software