Modules Environment

Environment modules provide a great way to easily customize your linux shell environment (PATH, MANPATH, INCLUDE, LD_LIBRARY_PATH), especially with loading or unloading a module file.

This is a system that allows you to easily change between different versions of compilers and other software, no matter what shell you use, without having to set a lot of environment variables by hand each time, making it easier to use software packages.

The workstations have a variety of compilers, libraries, and other bits of software installed. Some of it exists in multiple versions, and, for example, you may wish to switch between compilers for testing or you may wish to select a specific revision of Matlab.

The purpose of the module package is to simplify this for you.

On all workstations the modules package is available as standard; it provides for the dynamic modification of the user's environment via modulefiles.

Each modulefile contains the information needed to configure the shell for an application; 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.

The modulefiles are added to and removed from the current environment by the user. The environment changes contained in a modulefile can be summarized through the module command as well. If no arguments are given, a summary of the module usage and sub-commands are shown:

[user@workstation ~]# module
Modules Release Tcl x.x.x ($RCSfile: modulecmd.tcl,v $ $Revision: x.xxx $)
	Copyright GNU GPL v2 1991
Usage: module [ switches ] [ command ]
Switches:
	-t		terse format avail and list
	-l		long format avail and list
Commands:
	list         |  add|load            modulefile [modulefile ...]
	purge        |  rm|unload           modulefile [modulefile ...]
	reload       |  switch|swap        [oldmodulefile] newmodulefile
	             |  display|show        modulefile [modulefile ...]
	             |  avail              [modulefile [modulefile ...]]
	             |  whatis             [modulefile [modulefile ...]]
	             |  help               [modulefile [modulefile ...]]
	             |  path                modulefile
	             |  paths               modulefile
	             |  use                 dir [dir ...]
	             |  unuse               dir [dir ...]
	             |  source              scriptfile
	             |  apropos|keyword     string
	             |
	initlist     |  initadd             modulefile
	initclear    |  initprepend         modulefile
		     |  initrm              modulefile

avail

With the subcommand avail you get available list of module files (versions or names may change):

[user@workstation ~]# module avail
------------ /u/shared/programs/noarch/common/modulefiles ------------ 
mathematica/6.0.2(default) mkl/10.0.2.018(default) 
mathematica/6.0.1          mkl/9.0.1
------------ /u/shared/programs/x86_64/common/modulefiles ------------ 
cce/10.1.013(default)   intel/10.1.013(default) pgi/7.1-6(default)      
cce/9.0.1               intel/9.1               pgi/6.1
fce/10.1.013(default)   maple/11(default)       sm/2.4.34(default)      
fce/9.1                 maple/10                sm/2.2.3
idbe/10.1.013(default)  matlab/2007b(default)
idbe/9.1                matlab/2007a

The notation for the modulefilename is “name of the application/version and description”.

load

To use a particular module, run module load modulename. You don't need to list the full name of the module, as listed in module avail output, if you only use the first component, it will choose the latest version for you. (It actually chooses the last item alphabetically.)

[user@workstation ~]# module load cce

list

This lists all modules which are currently loaded into the users' environment (versions or names may change).

[user@workstation ~]# module list
Currently Loaded Modulefiles:
 1) cce/10.1.013 

unload

Use this command to unload one or more of the loaded module files (seen in list before).

[user@workstation ~]# module unload cce

whatis

If a module looks interesting, use this command to display the information contained within the given module file (versions or names may change).

[user@workstation ~]# module whatis cce
----------- /u/shared/programs/noarch/common/modulefiles ------------- 
----------- /u/shared/programs/x86_64/common/modulefiles ------------- 
        cce/10.1.013: loads the Intel(R) C++ Compiler 10.1.013

display

Use this command to see exactly what a given modulefile will do to your environment, such as what will be added to the PATH, MANPATH, etc. environment variables.

[user@workstation ~]# module display cce
-------------------------------------------------------------------
/u/shared/programs/x86_64/common/modulefiles/cce/10.1.013:

module-whatis	loads the Intel(R) C++ Compiler 10.1.013
prepend-path	PATH	/u/shared/programs/x86_64/common/intel/cce/10.1.013/bin
prepend-path	LD_LIBRARY_PATH	/u/shared/programs/x86_64/common/intel/cce/10.1.013/lib
prepend-path	MANPATH	/u/shared/programs/x86_64/common/intel/cce/10.1.013/man
prepend-path	INTEL_LICENSE_FILE	/u/shared/licenses/intel
-------------------------------------------------------------------

To automatically load modules when you log in to a system, put the module load modulename command in your shell's startup script.

For example:

  • if your shell is bash, put the command in your ~/.bashrc
  • if your shell is csh, put it in your ~/.cshrc.

If you change shells in your batch script you may need to explicitly load the modules environment (if your script does not use modules commands, there is, of course, no need to do this) by adding as the first line of your bash script:

. /etc/profile.d/modules.sh

or in case your script is csh derived:

source /etc/profile.d/modules.csh
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