Building software has become an increasingly complicated operation, as our software has many dependencies and we expect it to work both on your laptop and on the Grid. In addition, we support many Linux distributions and recent macOS versions.

ALICE uses aliBuild to build software.

aliBuild

• knows how to build software via per-package recipes,
• manages the dependencies consistently,
• can automatically download precompiled binaries if possible,
• rebuilds only what's necessary,
• allows several versions of the same software to be installed side by side.

Please follow the corresponding instructions below, according to your operating system.

Primary supported platforms:

• CentOS 7
• CentOS 8, AlmaLinux 8
• AlmaLinux 9

Platforms supported on a best-effort basis:

• macOS: Sonoma (14), Sequoia (15)
• Ubuntu: 20.04 LTS, 22.04 LTS, 24.04 LTS
• Fedora
• Linux Mint
  • Follow the instructions for the Ubuntu version your Linux Mint version is based on.
  • Specify the corresponding Ubuntu architecture when running aliBuild commands using the -a option (e.g. -a ubuntu2404_x86-64 for Ubuntu 24.04). Use the -a option also with alienv commands.

If your operating system is not listed, it does not mean our software won't work on it; it will be just more difficult for you to get support for it.

Only in case you cannot install aliBuild in the way described below, you can install aliBuild manually. This procedure should only be used as a fallback, in case you cannot follow the instructions for your operating system linked above.

With root permissions, i.e. sudo or as root, install the prerequisites and aliBuild 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
yum update -y
yum install -y alibuild

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

yum install -y epel-release
yum install -y dnf-plugins-core
yum config-manager --set-enabled powertools
yum update -y

dnf group install -y "Development Tools"

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_el8.x86-64/
enabled=1
gpgcheck=0
EOF
yum update -y
yum install -y alice-o2-full-deps alibuild

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

dnf install -y epel-release dnf-plugins-core
dnf update -y
dnf config-manager --set-enabled crb
dnf group install -y 'Development Tools'
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_el9.x86-64/
enabled=1
gpgcheck=0
EOF
dnf update -y
dnf install -y alice-o2-full-deps alibuild

Xcode bundles the necessary tools to build software in the apple ecosystem including compilers, build systems and version control.

• Download it from the App Store and install it.
• Open once installed. It will ask to install additional components. Approve the action.
• Open a terminal (Applications>Utilities>Terminal) and install the command line tools using: sudo xcode-select --install
• Approve the license conditions by: sudo xcodebuild -license

Homebrew is a command-line package manager for macOS used to install software packages (similar to yum on CentOS or apt on Ubuntu).

• Install Homebrew using the instructions on their webpage.
• Detect any problems regarding Homebrew and your system using: brew doctor.

If you have an existing ROOT installation on your system, it will interfere with the aliBuild installation and will cause difficult-to-debug compilation errors.

Please uninstall any existing copy of ROOT on your system. The uninstallation method depends on how you installed it. For example, if you originally installed ROOT using Homebrew, you should uninstall it using brew uninstall root.

After uninstalling ROOT, remove any reference to ROOT from your .zprofile, .zshrc and any other shell configuration files. Then close and re-open your terminal window.

Note that Homebrew does not run as root. Do not prepend sudo to any of the following commands.

• Install the prerequisites and aliBuild via: brew install alisw/system-deps/o2-full-deps alisw/system-deps/alibuild
• Set up Homebrew in your shell by: echo 'eval "$(/opt/homebrew/bin/brew shellenv)"' >> ~/.zprofile
• Close Terminal and reopen it to apply changes.

Update your package sources and install the required system packages:

sudo apt update -y
sudo apt install -y curl libcurl4-gnutls-dev build-essential gfortran libmysqlclient-dev xorg-dev libglu1-mesa-dev libfftw3-dev libxml2-dev git unzip autoconf automake autopoint texinfo gettext libtool libtool-bin pkg-config bison flex libperl-dev libbz2-dev swig liblzma-dev libnanomsg-dev rsync lsb-release environment-modules libglfw3-dev libtbb-dev python3-dev python3-venv python3-pip graphviz libncurses-dev software-properties-common gtk-doc-tools

Add the alisw PPA repository and install aliBuild as an Ubuntu package:

sudo add-apt-repository ppa:alisw/ppa
sudo apt update
sudo apt install python3-alibuild

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

yum install -y epel-release
yum install -y dnf-plugins-core
yum config-manager --set-enabled powertools
yum update -y

dnf group install -y "Development Tools"

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_fedora.x86-64/
enabled=1
gpgcheck=0
EOF
yum update -y
yum install -y alice-o2-full-deps alibuild

After installing aliBuild, configure it by adding the following lines to your ~/.bashrc, ~/.bash_profile, ~/.zshrc or ~/.zprofile (depending on your operating system and configuration):

export ALIBUILD_WORK_DIR="$HOME/alice/sw"
eval "$(alienv shell-helper)"

The first line tells what directory is used as "build cache", the second line installs a "shell helper" that makes easier to run certain aliBuild-related commands.

You need to close and reopen your terminal for the change to be effective. The directory ~/alice/sw will be created the first time you run aliBuild.

Note that this directory tends to grow in size over time and it is the one you need to clean up occasionally.

When aliBuild is installed on your computer and your prerequisites are satisfied, you can move to the next step.

See also shell rc utilities.

We assume your work area is ~/alice. Start with a clean shell where you are not in an alienv environment. Create the directory and move to it. (All the following commands need to be executed in this directory.):

mkdir -p ~/alice
cd ~/alice

Download O2Physics (and optionally O2):

aliBuild init O2Physics@master
aliBuild init O2@dev  # optional

If you perform ls under your work directory, you will see the development packages you have downloaded via aliBuild init, plus the alidist directory.

The alidist directory contains software recipes, telling aliBuild how the software is built.

You only need the O2 source code if you need to modify it. Otherwise, aliBuild will install the O2 version defined in `alidist` as a dependency of O2Physics.

Your `alidist` directory and your software source code are Git repositories **managed by you**. You need to keep them up to date manually.

aliDoctor O2Physics

aliDoctor will warn you if some packages have to be built as they could not be found on the system.

Build (or rebuild) full O2Physics with:

aliBuild build O2Physics

To set the maximum number of parallel jobs N, provide the -j N option.

See the Troubleshooting section for debugging tips if the build fails.

To build only parts of O2Physics, provide a space-separated list of requested directories (followed by /install) using the O2PHYSICS_COMPONENTS variable, e.g.:

O2PHYSICS_COMPONENTS="Common/install Tools/install Tutorials/install" aliBuild build O2Physics

On Linux, the components providing the required linked shared libraries also need to be included (e.g. `Tools/ML` for `O2Physics::MLCore`).

You will not find the packages you have built immediately available on your shell. We provide a tool called alienv that configures your shell according to the packages you want to load. alienv is capable of switching between different versions of the same package without a hassle.

Load the latest O2Physics version you have built.

alienv enter O2Physics/latest

The alienv enter command drops you to a new shell with the O2Physics environment. Unload the packages by simply exiting the environment with the exit command.

Dependencies are loaded automatically. Do not attempt to load O2 or ROOT as well! You will find them automatically in the environment. `alienv enter` is verbose and will inform you about the loaded packages.

If you have built several Git branches of O2Physics, you can enter the environment of a given branch `[branch]` with `alienv enter O2Physics/latest-[branch]-o2`.

You can list all your available packages with `alienv q`.

With frequent rebuilding of packages, obsolete builds can pile up and occupy a lot of precious disk space.

The simplest way to get rid of obsolete builds is to let aliBuild do its best by running:

aliBuild clean

which can take the optional argument --aggressive-cleanup that deletes also source code of built dependency packages and downloaded .tar.gz archives.

In general, it's good practice to run aliBuild clean always after aliBuild build.

This might not be enough, as aliBuild will not delete any build directory pointed to by a symlink that has "latest" in its name, even when that build is not needed by any other package any more. Manual intervention is therefore sometimes needed.

If you want to keep only the latest builds of your development packages (and their dependencies), you can make aliBuild delete the rest with a little trick.

1. Delete symlinks to all builds:

   find $ALIBUILD_WORK_DIR/$(aliBuild architecture)/ -mindepth 2 -maxdepth 2 -type l -delete
   find $ALIBUILD_WORK_DIR/BUILD/ -mindepth 1 -maxdepth 1 -type l -delete

   In case you specified the architecture manually (using the -a option with aliBuild build), you should replace $(aliBuild architecture) with your manually specified architecture.

2. Recreate symlinks to the latest builds of development packages (and their dependencies) by running aliBuild build for each development package.

3. Let aliBuild delete all the other builds by running aliBuild clean.

This requires that you have successfully built Git branch `[branch]` (e.g. `master`) of O2Physics with aliBuild (see Section [Build and rebuild](#build-and-rebuild)).

You also need to have `direnv` installed and hooked (see [instructions](https://direnv.net/docs/installation.html)) to load the correct build environment automatically when you enter the build directory (and to unload it when you exit).

This only builds O2Physics. If you have updated O2 or alidist, you first need to do a full build with aliBuild.

Make sure that you are not inside any environment! (You can check with `alienv list` for aliBuild environments and with `echo $VIRTUAL_ENV` for virtual Python environments.)

Go to the build directory.

cd "$ALIBUILD_WORK_DIR/BUILD/O2Physics-latest-[branch]/O2Physics"

Allow direnv to load the build environment. (Needed only once in a given directory.)

direnv allow

You should see a message starting with direnv: loading. If you don't, verify that you have direnv installed and hooked properly.

You can now rebuild and install entire O2Physics with

ninja install

or just a specific directory with

ninja <directory>/install

For example: ninja PWGCF/Tasks/install

Tip: You can redirect the terminal output to the standard aliBuild log file and see whether the build succeeded:

ninja install > ../log 2>&1 && echo "Good" || echo "Bad"

See also shell rc utilities.

A specific executable can be built in the staging directory stage/bin with

ninja stage/bin/<target>

For example: ninja stage/bin/o2-analysis-cf-correlations

The executable can then be executed directly from the staging directory:

stage/bin/<target>