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Modules, provides dynamic modification of a user's environment

The Modules package is a tool that simplify shell initialization and lets users easily modify their environment during the session with modulefiles.

Each modulefile contains the information needed to configure the shell for an application. Once the Modules package is initialized, the environment can be modified on a per-module basis using the module command which interprets modulefiles. Typically modulefiles instruct the module command to alter or set shell environment variables such as PATH, MANPATH, etc. modulefiles may be shared by many users on a system and users may have their own collection to supplement or replace the shared modulefiles.

Modules can be loaded and unloaded dynamically and atomically, in an clean fashion. All popular shells are supported, including bash, ksh, zsh, sh, csh, tcsh, fish, cmd, as well as some scripting languages such as tcl, perl, python, ruby, cmake and r.

Modules are useful in managing different versions of applications. Modules can also be bundled into meta-modules that will load an entire suite of different applications.

Quick examples

Here is an example of loading a module on a Linux machine under bash.

$ module load gcc/9.4.0
$ which gcc
$ /usr/local/gcc/9.4.0/linux-x86_64/bin/gcc

Now we'll switch to a different version of the module

$ module switch gcc gcc/10
$ which gcc

And now we'll unload the module altogether

$ module unload gcc
$ which gcc
gcc not found

Now we'll log into a different machine, using a different shell (tcsh).

% module load gcc/10.3
% which gcc

Note that the command line is exactly the same, but the path has automatically configured to the correct architecture.

Getting things running

The simplest way to build and install Modules on a Unix system is:

$ ./configure
$ make
$ make install

To learn the details on how to install modules see INSTALL.txt for Unix system or INSTALL-win.txt for Windows.


  • Tcl >= 8.5


Modules is distributed under the GNU General Public License, either version 2 or (at your option) any later version (GPL v2+). Read the file COPYING.GPLv2 for details.


See MIGRATING to get an overlook of the new functionalities introduced by each released versions. NEWS provides the full list of changes added in each version. The Changes document gives an in-depth view of the modified behaviors and new features between major versions. You may also look at the ChangeLog for the technical development details.

The doc directory contains both the paper and man pages describing the user's and the module writer's usage. To generate the documentation files, like the man pages (you need Sphinx >= 1.0 to build the documentation), just type:

$ ./configure
$ make -C doc all

The following man pages are provided:

module(1), ml(1), modulefile(4)

Test suite

Regression testing scripts are available in the testsuite directory (you need DejaGnu to run the test suite):

$ ./configure
$ make test

Once modules is installed after running make install, you have the ability to test this installation with:

$ make testinstall


Web site:

Online documentation:

GitHub source repository:

GitHub Issue tracking system:

SourceForge project page:

Code of conduct

Please note that Modules has a Code of conduct. By participating in the Modules community, you agree to abide by its rules.


Current core developer and maintainer is:

  • Xavier Delaruelle <xavier.delaruelle AT>

The following people have notably contributed to Modules and Modules would not be what it is without their contributions:

  • R.K. Owen
  • Kent Mein
  • Mark Lakata
  • Harlan Stenn
  • Leo Butler
  • Robert Minsk
  • Jens Hamisch
  • Peter W. Osel
  • John L. Furlani