3.1. Software Modules

HPC comes with a wide variety of software packages and libraries. These software packages are managed using a module system. A module is a software package that can be loaded and unloaded on the cluster. The module system allows users to manage their software dependencies and environments.

3.1.1. Available Modules

Use the module avail command to list all the software modules available on the cluster. The output will show the available software modules and their versions.

To search for modules with <string> in their name, use module avail <string>. For example, to list all modules with cuda in their name, run module avail cuda.

Note

See a list of software modules available on the FASRC Cannon cluster here.

3.1.2. Managing Software Modules

The following commands are used to manage software modules:

Command	Description
module avail	List all available software modules.
module avail <string>	List all available software modules that contain <string> in their name.
module load <module_name>	Load a software module.
module unload <module_name>	Unload a software module.
module list	List all loaded software modules.
module purge	Unload all loaded software modules.

Tip

You can use ml as a shortcut for common commands:

Command	Shortcut
module list	ml
module load <module_name>	ml <module_name>
module unload <module_name>	ml -<module_name>

3.1.3. How do modules work?

Each module is defined by a script that runs when the module is loaded. This script modifies environment variables such as PATH, LD_LIBRARY_PATH, etc. to make the software accessible from your terminal session. You can use module show <module_name> to show a module’s script.

These changes to the terminal environment will persist until module unload <module_name> or module purge is called. They act independently of other modifications to environment variables, namely virtual environments.

You can read more about modules at the Lmod documentation.