Pittsburgh Supercomputing Center 

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Module Software

The Module package provides for the dynamic modification of a users's environment via module files. Module can be used:

  • to manage necessary changes to the environment, such as changing the default path or defining environment variables
  • to manage multiple versions of applications, tools and libraries
  • to manage software where name conflicts with other software would cause problems

Modules have been created for many of the software packages installed on PSC systems. They make your job easier by defining environment variables and adding directories to your path which are necessary when using a given package.

Interactive use

Module is available automatically for interactive use. However, if you are using modules, you should not switch your shell from your login shell during your interactive session.

Batch use

To use module commands in a batch job, add this command to your script:

On blacklight or salk:

source /usr/share/modules/init/shell-name

where shell-name is the shell you are using, e.g., csh, tcsh, bash, sh or ksh.

Dealing with multiple versions of software

Often multiple versions of a given software package are installed.   You must load the module for the specific version that you want.  To  see what versions are available, use the module available command.

module availabile package-name

This example shows that several versions of TAU are installed, from 2.19 to 2.23.1:

tg-login1:~> module avail tau
-------------------------- /usr/local/opt/modulefiles --------------------------
tau/2.19         tau/2.20.2        tau/2.23
tau/2.19.2        tau/2.20.3        tau/2.23.1
tau/2.20          tau/2.21(default)

To see which is the default version, type

module show package-name

Here, for example, you can see that  2.21 is the default version of TAU

tg-login1:~> module show tau
module           load java
setenv           TAU_ROOT_DIR /usr/local/packages/TAU/usr/2.21
setenv           TAU_MAKEFILE /usr/local/packages/TAU/usr/2.21/x86_64/lib/Makefile.tau-icpc-mpi-pdt
setenv           JAVA_ROOT_DIR /usr/java/jdk1.6.0_21/jre/bin
prepend-path     PATH /usr/local/packages/TAU/usr/2.21/x86_64/bin
prepend-path     PATH /usr/local/packages/TAU/usr/2.21
prepend-path     PATH /usr/java/jdk1.6.0_21/jre/bin
prepend-path     MANPATH /usr/local/packages/TAU/usr/2.21/man

To load the default version, just type

module load package-name

so typing

module load tau

loads version 2.21, in this example.

To load a different version, use the specific module name. For example, to load TAU version 2.19 instead of the default, type

module load tau/2.19

Module commands

Some useful module commands are:

module avail lists all the available modules
module help foo displays help on module foo
module display foo indicates what changes would be made to the environment by loading module foo without actually loading it
module load foo loads module foo
module list displays your currently loaded modules
module swap foo1 foo2 switches loaded module foo1 with module foo2
module unload foo reverses all changes to the environment made by previously loading module foo


Modules for different packages or different versions of the same package can sometimes interfere with each other. To ensure that you have the environment that you expect, you should always check which modules are loaded and use the unload command to remove any that you don't need before using load for the ones you want, or use swap to switch modules.


The module load command loads a specific module. For example, the command

module load icc/10.1.015

sets the proper definitions for you to use version 10.1.015 of the icc compiler. When you are done with a module you can unload it and undo its effect.

module unload icc/10.1.015

Or you can swap it with another module if you want to use a different version of the same software.

module swap icc/10.1.015 icc/10.1.017

After you issue this command, when you run the icc compiler you will be using version 10.1.017 of the compiler, not version 10.1.015.