Supercomputing Institute Technical User Support

Modules and user environments


What is a user environment
What is the Modules package?

What is a user environment?

A "user environment" is a collection of variables that specify the behavior of your shell and/or applications. The PATH and MANPATH variables are two of the most critical ones; these control where your shell (or other applications) looks for binaries that you wish to run and where man looks for manpages.

What is the Modules package?

We are using the Modules package to manipulate user environments. Modules is a set of tools that allows users to modify their environment (which consists of variables and search-paths needed to run various applications, see above). The Modules package is initialized with the following lines in your .cshrc file (assming that you are running tcsh):

# initialize and load modules

unsetenv PATH MANPATH
if( -e /usr/local/share/modules/init/tcsh ) then
   source /usr/local/share/modules/init/tcsh
endif

module load base

Please do not remove them. As you can see above, Modules syntax is basically:

% module <action> [modulefile name(s)]

In the above case, we are "loading" a module (or modulefile, we'll refer to them as modules) called "base". The "base" module sets the PATH and MANPATH variables, and a few others, so that you may access most standard Unix system applications.

In order to keep your paths within the space limits of the system*, we have set up individual modules for special software packages. For example, to run the Midas package, the Midas module must be loaded. This can be done with the following command:

% module load midas

When you are finished with Midas, you could unload the module:

% module unload midas

If you find yourself frequently using Midas, you could edit your .cshrc file to load the midas module automatically with the command:

module load base midas

Note that the "base" module should always be loaded first. To obtain a list of available modules, use the command module avail or see the list of modules (above). Man pages are available as module(1) and modulefile(5).

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* Unix paths are limited to a certain amount of space. Setting the PATH and MANPATH variables to include every software package installed on our systems is not possible. The Modules package allows you to set only the paths that you need and to unset these paths when you are finished.

This information is available in alternative formats upon request by individuals with disabilities. Please send email to alt-format@msi.umn.edu or call 612-624-0528.

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