Lua Modulefile Functions

Lua is an efficient language built on simple syntax. Readers wanting to know more about lua can see http://www.lua.org/. This simple description given here should be sufficient to write all but the most complex modulefiles.

It is important to understand that modulefiles are written in the positive. That is, one writes the actions necessary to activate the package. A modulefile contains commands to add to the PATH or set environment variables. When loading a modulefile the commands are followed. When unloading a modulefile the actions are reversed. That is the element that was added to the PATH during loading, is removed during unloading. The environment variables set during loading are unset during unloading.

prepend_path (“PATH”,”/path/to/pkg/bin”):
prepend to a path variable the value.
append_path (“PATH”,”/path/to/pkg/bin”):
append to a path variable the value.
remove_path (“PATH”,”/path/to/pkg/bin”):
remove value from path. This command is a no-op when the mode is unload.
setenv (“NAME”, “value”):
assigns to the environment variable “NAME” the value.
pushenv (“NAME”, “value”):
sets NAME to value just like setenv. In addition it saves the previous value in a hidden environment variable. This way the previous state can be returned when a module is unloaded.
unsetenv (“NAME”):
unset the value associated with “NAME”. This command is a no-op when the mode is unload.
whatis (“STRING”):
The whatis command can be called repeatedly with different strings. See the Administrator Guide for more details.
help ( [[ help string ]]):
What is printed out when the help command is called. Note that the help string can be multi-lined.
pathJoin (“/a”,”b/c/”,”d/”):
builds a path: “/a/b/c/d”, It combines any number of strings with one slash and removes excess slashes. Note that trailing slash is removed. If you need a trailing slash then do pathJoin(“/a”,”b/c”) .. “/” to get “/a/b/c/”.
load (“pkgA”, “pkgB”, “pkgC”):
load all modules. Report error if unable to load.
try_load (“pkgA”, “pkgB”, “pkgC”):
load all modules. No errors reported if unable to load.
always_load (“pkgA”, “pkgB”, “pkgC”):
load all modules. However when this command is reversed it does nothing.
set_alias (“name”,”value”):
define an alias to name with value.
unload (“pkgA”, “pkgB”):
When in load mode the modulefiles are unloaded. It is not an error to unload modules that where not loaded. When in unload mode, this command does nothing.
family (“name”):
A user can only have one family “name” loaded at a time. For example family(“compiler”) would mean that a user could only have one compiler loaded at a time.
prereq (“name1”, “name2”):
The current modulefile will only load if all the listed modules are already loaded.
prereq_any (“name1”, “name2”):
The current modulefile will only load if any of the listed modules are already loaded.
conflict (“name1”, “name2”):
The current modulefile will only load if all listed modules are NOT loaded.

Extra functions

The entries below describe several useful commands that come with Lmod that can be used in modulefiles.

os.getenv (“NAME”):

Ask for environment for the value of “NAME”. Note that if the “NAME” might not be in the environment, then it is probably best to do:

local foo=os.getenv("FOO") or ""

otherwise foo will have the value of nil.

capture (“string”):
Run the “string” as a command and capture the output. This function uses the value of LD_PRELOAD and LD_LIBRARY_PATH found when Lmod is configured. Use subprocess if you wish to use the current values.
subprocess (“string”)
Run the “string” as a command and capture the output.
isFile (“name”):
Returns true if “name” is a file.
isDir (“name”):
Returns true if “name” is a directory.
splitFileName (“name”):
Returns both the directory and the file name. local d,f=splitFileName("/a/b/c.ext"). Then d="/a/b", f="c.ext"
LmodMessage (“string”,...):
Prints a message to the user.
LmodError (“string”,”...”):
Print Error string and exit without loading the modulefile.
mode ():
Returns the string “load” when a modulefile is being loaded and “unload” when unloading.
isloaded (“NAME”):
Return true when module “NAME” is loaded.
LmodVersion ():
The version of lmod.
execute {cmd=”<any command>”,modeA={“load”}}
Run any command with a certain mode. For example execute {cmd=”ulimit -s unlimited”,modeA={“load”}} will run the command ulimit -s unlimited as the last thing that the loading the module will do.

Modifier functions to prereq and loads

atleast (“name”,”version”):
This modifier function will only succeed if the module is “version” or newer.
between (“name”,”v1”,”v2”):
This modifier function will only succeed if the module’s version is equal to or between “v1” and “v2”.
latest (“name”):
This modifier function will only succeed if the module has the highest version on the system.

Introspection Functions

The following functions allow for more generic modulefiles by finding the name and version of a modulefile.

myModuleName ():
Returns the name of the current modulefile without the version.
myModuleVersion ():
Returns the version of the current modulefile.
myModuleFullName ():
Returns the name and version of the current modulefile.
myModuleUsrName ():
Returns the name the user specified to load a module. So it could be the name or the name and version.
myFileName ():
Returns the absolute file name of the current modulefile.
myShellName ():
Returns the name of the shell the user specified on the command line.
myShellType ():
Returns the shellType based on the name of the shell the user specified on the command line. It returns sh for sh, bash, zsh, csh for csh, tcsh. Otherwise it is the same as myShellName ().
hierarchyA (“fullName”, level):
Returns the hierarchy of the current module. See the section on Generic Modules for more details.