This package is based on Modules (http://modules.sourceforge.net/). Both Modules and EnvMaster allow packages to be installed in separate directories from each other and ’loaded’ into the users environment on demand. They also allow multiple versions of the same package to be installed concurrently and a particular version loaded.
EnvMaster attempts to address some of the limitations of the original design, not least its dependence on TCL. I have also tried to automate some of the more repetitive aspects of creating modules.
First untar the distribution. It is usually wisest to install separate from your Python distribution like this:
export ENVMASTER_ROOT=/opt/envmaster
python setup.py install --prefix=$ENVMASTER_ROOT
export PATH=$ENVMASTER_ROOT/bin:$PATH
export PYTHONPATH=$ENVMASTER_ROOT/lib/pythonX.X/site-packages:$PYTHONPATH
Where ’pythonX.X’ is the version of your Python distribution. ENVMASTER_ROOT can be any directory you have write access to.
In the case where there is no Python available, and you need to load it with EnvMaster, a ’frozen’ version of EnvMaster needs to be prepared. More to come on this...
In the case where the system has an older version of Python available (say 2.4) and you want to load a newer version using EnvMaster (say 2.6), some care is required for setting up paths. When you do the install (as above) with the system python (2.4), the site packages directory will be called $ENVMASTER_ROOT/lib/python2.4/site-packages. This is fine when using the system Python. However, if you were to load Python 2.6 with EnvMaster, it won’t be able to find it’s components because it will be looking in $ENVMASTER_ROOT/lib/python2.6/site-packages. The best workaround is to create a link called $ENVMASTER_ROOT/lib/python2.6 pointing to $ENVMASTER_ROOT/lib/python2.4. Also, it pays to check that distutils hasn’t re-written the first line of envmastercmd.py.
On a related note, it is best to load the newer version of Python first and separately from other Python packages, otherwise the wrong site packages directory will be used.
For tcsh users:
source $ENVMASTER_ROOT/init/tcsh
For bash users
source $ENVMASTER_ROOT/init/bash
For zsh users
source $ENVMASTER_ROOT/init/zsh
Your $ENVMASTERPATH variable needs to be set to the location of your module files. See Section 3.
Once EnvMasters is initialised, the following commands will be available:
envmaster list
Displays the currently loaded modules
envmaster avail
Displays all the modules that are available. Normally various versions of each module are available. The default version is marked with (default).
envmaster load module/version
Loads a module. If version not specified, default is used.
envmaster unload module/version
Unloads a currently loaded module
envmaster disp module/version
Displays what a module does (without loading it). If version not specified, default is used.
envmaster swap module/version module/version
Switches between versions of a module.
from envmaster import pyutils
Currently there are 2 methods: pyutils.load() and pyutils.unload() which take a single string with a module name, or a list.
The $ENVMASTERPATH variable must be set to a semi-colon separated list of directories. Each of these directories is searched for EnvMaster files. This is usually in a separate tree from the software installation.
Files under each directory in $ENVMASTERPATH are treated as EnvMaster
files if the first line starts with #%EnvMaster1.0. There are two
sorts of EnvMaster files: versioned and unversioned. Unversioned files
sit at the root of the directory. A file here will show up as an
available module. Using this type is not recommended because the whole
idea of EnvMasters is to have multiple versions of software installed.
However in some instances there is only ever one version and this does
make sense.
The second type is a versioned EnvMaster file. These live in subdirectories immediately below the root of the directory and these directories usually have the same name as the software they load. They are normally named to match the version of the software ie python/2.6.5. There can be many of these files, one per version installed. The default version is the first, or dictated by the version.py file if installed (see below). If the version of the module to be loaded is not specified by the user, it is this default version that is used. The user can of course override this and specify a particular version they wish to use.
For example, for the directory layout below, there are 2 EnvMasters, one called ’unversionedsw’ that is not versioned. The second (’python’) has 3 versions that can be chosen between.
$ENVMASTERPATH=/opt/modules
/opt/modules/unversionedsw
/opt/modules/python/2.5.1
/opt/modules/python/2.6.0
/opt/modules/python/2.6.5
EnvMaster files are just fragments of Python so can contain any valid Python statements. There are a number of functions meaningful in a EnvMaster context. The following discusses the operations that are performed for each function when a module is loaded. It is worth noting the opposite is performed when modules are unloaded (ie variables unset etc).
module.setAll(path)Searches the path given and sets the following variables in certain conditions, where MODNAME is the name of the EnvMaster in capitals (ie PYTHON)
- $MODNAME_ROOT is set to the root path specified
- If it exists and contains files, the ’bin’ subdirectory is added to the $PATH and put into the $MODNAME_BIN_PATH variable
- If it exists and contains files, the ’lib’ subdirectory is added to the $LD_LIBRARY_PATH (or whatever variable makes sense for the current OS) and put into the $MODNAME_LIB_PATH variable
- If it exists and contains files or sub directories, the ’include’ subdirectory is put into the $MODNAME_INCLUDE_PATH variable
- If either the ’man’ subdirectory or ’share/man’ subdirectory exists and contains files it is added to the $MANPATH and put into the $MODNAME_MAN_PATH variable.
- If the ’lib/pythonX.X/site-packages’ directory exists (where X.X is the version of Python EnvMaster is running) and contains files or subdirectories, then it is added to the $PYTHONPATH and put into the $MODNAME_PYTHON_PATH variable.
Normally, setAll() is the only method that needs to be called as it handles most common situations. Other methods which can be added are:
module.setBin(binpath)Adds binpath to the $PATH and put into $MODNAME_BIN_PATH
module.setLib(libpath)Adds libpath to the $LD_LIBRARY_PATH (or whatever variable makes sense for the current OS) and put into $MODNAME_LIB_PATH.
module.setMan(manpath)Adds manpath to the $MANPATH and put into $MODNAME_MAN_PATH
module.setInclude(includepath)Puts includepath into $MODNAME_INCLUDE_PATH
module.setPython(pythonpath)Adds pythonpath to $PYTHONPATH and put into $MODNAME_PYTHON_PATH
module.load(modnames)Load specified EnvMaster(s). Use of this function is not recommended as it makes it difficult to manage dependencies. It is better to force the user to load necessary EnvMasters themselves with the module.prereq function.
module.swap(old,new)Unloads module given in old and replaces it with that contained in new. See comments above on load().
module.prereq(modnames)Checks at least one of the specified modules is loaded. If you want to check a number of modules is loaded, then call this function separately once for each module. If the module isn’t loaded, an error is returned to the user and nothing is loaded.
module.conflict(modnames)Raises an error if one of the specified modules is loaded.
module.whatis(description)Sets the description of the modules. This is only seen when doing a ’EnvMaster disp’
module.setVar(value,varname,addpkgname=False)Sets the environment variable named in varname to value. If addpkgname is True, then MODNAME_ is prepended to the varname.
module.setPath(path,varname)Prepends path onto environment variable specified in varname. Designed to use with $PATH and other environment variables that contain a list of paths.
If present, a file with the name of ’version.py’ in a versioned
EnvMasters directory is parsed to choose which version is the default.
This file needs to start with #%EnvMaster1.0 and can contain any
number of Python statements. It need only contain one other line that
sets the Python variable ’version’ to a string containing the version
number that should be made the default. Here is an example:
#%EnvMaster1.0
version = ’1.0.0’When configuring software, use the prefix option to install the software in a uniquely versioned directory. For autoconf software:
./configure --prefix=/opt/python/2.6.5
For python software
python setup.py install --prefix=/opt/matplotlib/1.0.0
Then create a EnvMaster file to match
Utility to ease transition from traditional modules to EnvMasters. More to come...
The file $ENVMASTER_ROOT/lib/pythonX.X/site-packages/EnvMaster/envmasterconf.py contains a number of settings. Changing this file will allow you to override almost any aspect of EnvMaster.