HP XC System Software User's Guide Version 3.2

3 Configuring Your Environment with Modulefiles
The HP XC system supports the use of Modules software to make it easier to configure and
modify the your environment. Modules software enables dynamic modification of your
environment by the use of modulefiles.
This chapter addresses the following topics:
• “Overview of Modules” (page 37)
• “Supplied Modulefiles” (page 38)
• “Modulefiles Automatically Loaded on the System” (page 40)
• “Viewing Available Modulefiles” (page 40)
• “Viewing Loaded Modulefiles” (page 40)
• “Loading a Modulefile” (page 40)
• “Unloading a Modulefile” (page 41)
• “Viewing Modulefile-Specific Help” (page 41)
• “Modulefile Conflicts” (page 41)
• “Creating a Modulefile” (page 42)
3.1 Overview of Modules
A modulefile contains information to configure the shell for an application. Typically, a modulefile
contains instructions that alter or set shell environment variables, such as PATH and MANPATH,
to enable access to various installed software.
Modules enable multiple versions of the same software to be used in your environment in a
controlled manner. For example, two different versions of the Intel C compiler can be installed
on the system at the same time – the version used is based upon which Intel C compiler modulefile
is loaded.
The HP XC software provides a number of modulefiles. You can also create your own modulefiles.
Modulefiles can be shared by many users on a system, and users can have their own collections
of modulefiles to supplement or replace the shared modulefiles.
For further information about the Modules software supplied with the HP XC system, see the
Modules Web site at the following URL:
http://sourceforge.net/projects/modules/
A modulefile does not provide configuration of your environment until it is explicitly loaded.
That is, the specific modulefile for a software product or application must be loaded in your
environment (with the module load command) before the configuration information in the
modulefile is effective.
You or your system administrator can configure your environment so that any desired modulefiles
are automatically loaded for you when you log in to the system. You can also load a modulefile
yourself, as described in “Loading a Modulefile” (page 40).
The Modules software is initialized when you log in to the HP XC system. It provides access to
the commands that you can use to display information about modulefiles, load or unload
modulefiles, or view a list of available modulefiles.
Modulefiles do not affect packages other than their intended package. For example, a modulefile
for a compiler will not adjust MPI_CC (the environment variable used by HP-MPI to control
which compiler to use). A modulefile for a compiler simply makes it easier to access that particular
compiler; it does not try to determine how the compiler will be used.
Similarly, a modulefile for HP-MPI will not try to adjust LD_LIBRARY_PATH to correspond to
the compiler that the mpicc command uses. The modulefile for MPI simply makes it easier to
3.1 Overview of Modules 37