Installing O2 and O2Physics

ALICE software has several dependencies: aliBuild takes care of downloading them for you. aliBuild can also automatically download precompiled binaries if possible.

Installing aliBuild

Follow the instructions here. Do not follow "build the packages" on that page.

Prepare your source code

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 folder):

mkdir -p ~/alice
cd ~/alice
 

Download O2 and O2Physics:

aliBuild init O2@dev
aliBuild init O2Physics@master
 

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

The alidist directory contains software recipes, telling aliBuild how the software is built. Your alidist directory and your software source code are Git directories managed by you: you need to keep them up-to-date manually.

Check your prerequisites

aliDoctor O2Physics

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

Build and rebuild

aliBuild build O2Physics

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

Use your local software installations

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.

Warning

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.

Tip

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.

Building partially for development using ninja

Note

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

You also need to have direnv installed to load the correct build environment automatically when you enter the build directory (and to unload it when you exit).

Warning

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

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 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"
 

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>