Modules Environment Management on Triton

Overview

The Environment Modules package provides for dynamic modification of a user's shell environment. Module commands set, change, or delete environment variables, typically in support of a particular application. They also let the user choose between different versions of the same software or different combinations of related codes.

For example, if the pgi module and mpich-mx module are loaded and the user compiles with mpif90, the generated code is compiled with the Portland Group Fortran 90 compiler and MPI libraries utilizing the Myrinet switch are linked. By unloading the mpich-mx module, loading the mpich module, and compiling with mpif90, the Portland compiler is used but linked with the gigabit ethernet libraries.

Modules on Triton

Several modules that determine the default Triton environment are loaded at login time.

Useful Modules Commands

Here are some common module commands and their descriptions:

• module list - List the modules that are currently loaded
• module avail - List the modules that are available
• module display <module_name> - Show the environment variables used by <module name> and how they are affected
• module unload <module name> - Remove <module name> from the environment
• module load <module name> - Load <module name> into the environment
• module switch <module 1 name> <module 2 name> - Replace <module 1 name> with <module 2 name> in the enviornment

Note that you must remove some modules before loading others. For example, if the pgi compiler is loaded, you must unload it before you can load intel. Also, some modules depend on others so may be loaded or unloaded as a consequence of another module command. For example, if pgi and openmpi_mx are both loaded, running the command unload pgi will automatically unload openmpi_mx. Subsequently issuing the load intel command does not automatically reload openmpi_mx.

Complete documentation is available in the module(1) and modulefile(4) manpages.