4.2 Environment module systems

Many, but not all, application software require, that the user loads an environment module before starting the program. The environment module system is needed as the programs and other tools often have contradictory requirements related to compilers and libraries. For example, it is often necessary to have access to older versions of an application, or to have a library configured with different options for different applications.

The syntax of the environment module loading is:

module load software_environment_name

For example to use R statistics software in taito-shell.csc.fi, you must first run command:

  module load r-env

This command adds the R executable to the search path and sets up environment variables that R needs. Only after that you can launch the actual R application.

Environment modules provide a convenient way to dynamically change the user's environment so that different compiler suites and application versions can be used more easily. Modules system modifies the environment variables of the user's shell environment so that the correct versions of executables are in the path and linker can find the correct version of needed libraries. For example, the command R points to different R versions depending of the loaded R module.

At the moment CSC is using two slightly different module environment tools:

1. Environment Modules Project

Supercomputer sisu.csc.fi uses TCL based module system developed by the Environment Modules Project (http://modules.sourceforge.net/). In this system all available modules are listed with command:

module avail

Loading module files is done with commands:

module load modulefilename

More information about this module environment can be found from the Sisu user guide.

2. Lmod

Taito.csc.fi supercluster uses a more recently developed version of environment modules called Lmod. It is developed at Texas Advanced Computing Center (TACC) and it is implemented using Lua programming language. In this system, all the installed modules can be listed with command:

module spider

Lmod uses hierarchical module structure which means that you may first need to load modules higher in the hierarchy before a specific module can be loaded. More details about the Lmod system can be found from the Taito user guide.

 

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