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ITCWeb: Modules Approach to Environment Management

Modules Approach to Environment Management

Introduction

 Modules provides an easy mechanism for dynamically modifying a user's environment via modulefiles. Each modulefile contains the information needed to configure the shell for an application. Typically modulefiles instruct the module command to alter or set shell environment variables such as PATH, MANPATH, etc.

Module commands

To get a usage list of module options type the following (the listing has been abbreviated to only those commands discussed in this webpage) : 


 % module help

  Available Commands and Usage:

        +  add|load     modulefile [modulefile ...]
        +  rm|unload    modulefile [modulefile ...]
        +  switch       modulefile1 modulefile2
        +  display      modulefile [modulefile ...]
        +  avail|which        path [path]
        +  list
        +  help         modulefile [modulefile ...]

module list
This lists all the modules which are currently loaded into the users environment.

module avail|which
This options lists all the modules which are available to be loaded. The "which" option provides descriptions about the available modules. Notice that many of them have version numbers associated with them. Modules makes it easy to switch compiler application versions. The module name without a version number is the production default.

module help modulefile
If a module looks interesting, to get more information use this command to display the `help' information contained within the given module file. 


 $ module help icc

----------- Module Specific Help for 'icc/7.0' --------------------

        Intel Software: Intel icc

        This module loads the lastest versions of icc.

        *** No Module Specific Help for icc/7.0 ***

module display modulefile
Use this command to see exactly what a given modulefile will do to your environment, such as what will be added to the PATH, MANPATH, etc. environment variables.

module load modulefile
This adds one or more modulefiles to the user's current environment. It does so silently, unless there is a problem with a modulefile.

If you load the generic name of a module, you will get the default version. To load a specific version, load the module using its full specification, e.g.: 

  $ module add icc/7.0
module unload modulefile
This removes any listed modules from the user's current environment. The modules can be removed in any order. 
  $ module unload icc

module switch modulefile_old modulefile_new
This command demonstrates the true advantages of modules. Different versions of entire software packages can be replaced with a single module command.

Sources of Information on Modules

Other information on modules can be found at the following site (http://modules.sourceforge.net/).

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