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Using Modules

See this article in context within the following user guides: Titan

The modules software package allows you to dynamically modify your user environment by using pre-written modulefiles.

Modules Overview

Each modulefile contains the information needed to configure the shell for an application. After the modules software package is initialized, the environment can be modified on a per-module basis using the module command, which interprets a modulefile.

Typically, a modulefile instructs the module command to alter or set shell environment variables such as PATH or MANPATH. Modulefiles can be shared by many users on a system, and users can have their own personal collection to supplement and/or replace the shared modulefiles.

As a user, you can add and remove modulefiles from your current shell environment. The environment changes performed by a modulefile can be viewed by using the module command as well.

More information on modules can be found by running man module on OLCF systems.

Summary of Module Commands
Command Description
module list Lists modules currently loaded in a user’s environment
module avail Lists all available modules on a system in condensed format
module avail -l Lists all available modules on a system in long format
module display Shows environment changes that will be made by loading a given module
module load Loads a module
module unload Unloads a module
module help Shows help for a module
module swap Swaps a currently loaded module for an unloaded module
Re-initializing the Module Command

Modules software functionality is highly dependent upon the shell environment being used. Sometimes when switching between shells, modules must be re-initialized. For example, you might see an error such as the following:

$ module list
-bash: module: command not found

To fix this, just re-initialize your modules environment:

$ source $MODULESHOME/init/myshell

Where myshell is the name of the shell you are using and need to re-initialize.

Examples of Module Use

To show all available modules on a system:

$ module avail   
------------ /opt/cray/modulefiles ------------
atp/1.3.0                          netcdf/4.1.3                       tpsl/1.0.01
atp/1.4.0(default)                 netcdf-hdf5parallel/4.1.2(default) tpsl/1.1.01(default)
atp/1.4.1                          netcdf-hdf5parallel/4.1.3          trilinos/

To search for availability of a module by name:

$ module avail -l netcdf
- Package -----------------------------+- Versions -+- Last mod. ------
netcdf/3.6.2                                         2009/09/29 16:38:25
netcdf/3.6.2                                         2011/12/09 18:07:31
netcdf/4.1.3                              default    2011/12/12 20:43:37

To show the modulefiles currently in use (loaded) by the user:

$ module list
Currently Loaded Modulefiles:
  1) modules/                           12) pmi/3.0.0-1.0000.8661.28.2807.gem
  2) xe-sysroot/4.0.30.securitypatch.20110928  13) ugni/2.3-1.0400.3912.4.29.gem
  3) xtpe-network-gemini                       14) udreg/2.3.1-1.0400.3911.5.6.gem

To show detailed help info on a modulefile:

$ module help netcdf/4.1.3 
------------ Module Specific Help for 'netcdf/4.1.3' ------------
  New version of hdf5 1.8.7 and netcdf 4.1.3
Product and OS Dependencies:
  hdf5_netcdf 2.1 requires SLES 11 systems and was tested on Cray XE and

To show what a modulefile will do to the shell environment if loaded:

$ module display netcdf/4.1.3
setenv           CRAY_NETCDF_VERSION 4.1.3 
prepend-path     PATH /opt/cray/netcdf/4.1.3/gnu/45/bin 

To load or unload a modulefile

$ module load netcdf/4.1.3
$ module unload netcdf/4.1.3

To unload a modulefile and load a different one:

$ module swap netcdf/4.1.3 netcdf/4.1.2