Environment modules on the Nevis particle-physics Linux cluster

Environment modules are a way of setting up a Linux shell environment. On the cluster, we use the module to set up software packages available on the applications server.

Quick start guide

To set up ROOT:

module load root

To set up Geant4:

module load geant4

To see what packages and versions are available:

module avail

If you just want to see the versions for a particular package, e.g., ROOT:

module avail root

To get a brief description of a given package, e.g., Geant4.9.6:

module whatis geant/4.9.6

To get a longer description:

module help geant/4.9.6

What are environment modules?

The command line environment you use to issue commands in Linux is called the shell. Your shell has an "environment": a collection of variables, aliases, and definitions to make the shell and its environment easier to use. A software package that is not built-in to Linux (such as ROOT or Geant4) needs the shell environment to be set up in various ways: defining shell variables such as $ROOTSYS, adding binary executables to the shell's search path variable $PATH, adding library locations to the shell's library search variable $LD_LIBRARY_PATH, etc.

Environment modules are a way taking care of these details for you. Instead of having to type something like:

export ROOTSYS=/usr/nevis/ROOT-5.34.23
export PATH=$ROOTSYS/bin:$PATH
export LD_LIBRARY_PATH=$ROOTSYS/lib:$LD_LIBRARY_PATH

every time you use ROOT, you can just type this instead:

module load root

Another advantage of environment modules is that they are shell-independent. For example, the above export commands are valid in bash and zsh, but in csh you must use:

setenv ROOTSYS /usr/nevis/ROOT-5.34.23
setenv PATH $ROOTSYS/bin:$PATH
setenv LD_LIBRARY_PATH $ROOTSYS/lib:$LD_LIBRARY_PATH

but even in csh, the environment modules command is still module load root.