When logging on a HEPIX enabled machine like those in the lxplus.cern.ch cluster, the user environment is customized with experiment specific settings (AKA group login).

The LHCb group login script lives in the project LbEnvBootstrap and is deployed as /cvmfs/lhcb.cern.ch/lib/etc/cern_profile.sh (there's a tcsh version too, but take into account our UnixShellSupport).

The group login script has the task of

• setting some CERN specific environment variables
• set up the LHCb User Environment (LbEnv) for one of the available flavours

LHCb User Environment deployment flavours

The LHCb User Environment is available on /cvmfs/lhcb.cern.ch in 3 flavours:

stable

(default) version valid for production use. Currently (December 2019) it redirects to LbLogin, as LbEnv is not yet in production

testing

validation version in preparation for the next stable version

• when a bug is fixed in a tool, the new version is first deployed in the testing flavour and after some validation is moved to stable

unstable

developers' playground, new features or backward incompatible changes are first deployed in the unstable flavour

Tuning

The behaviour of LHCb group login script can be tuned by the user via special files in the $HOME directory:

~/.nogrouplogin

if present, completely disable environment customization

~/.nolbenv

if present, disable LbEnv, but keep CERN specific variables

~/.lbenv_flavour

it must contain any of stable, testing or unstable to select the version of the LbEnv deployment to use. If missing or invalid, it is equivalent to stable

For example, to enable the testing flavour:

# make sure the customization is enabled
rm ~/.nogrouplogin ~/.nolbenv
# select "testing" flavour
echo testing > ~/.lbenv_flavour

For backward compatibility it also honors some legacy customization files, see https://gitlab.cern.ch/lhcb-core/LbEnvBootstrap/blob/master/README.md for details.

-- MarcoClemencic - 2019-04-24