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Diffstat (limited to 'lib/spack/docs/configuration.rst')
| -rw-r--r-- | lib/spack/docs/configuration.rst | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/lib/spack/docs/configuration.rst b/lib/spack/docs/configuration.rst index 5f76a76c81..f1648eb4e0 100644 --- a/lib/spack/docs/configuration.rst +++ b/lib/spack/docs/configuration.rst @@ -261,3 +261,52 @@ The merged configuration would look like this: - /lustre-scratch/$user - ~/mystage $ _ + +.. _config-file-variables: + +------------------------------ +Config file variables +------------------------------ + +Spack understands several variables which can be used in config file paths +where ever they appear. There are three sets of these variables, Spack specific +variables, environment variables, and user path variables. Spack specific +variables and environment variables both are indicated by prefixing the variable +name with ``$``. User path variables are indicated at the start of the path with +``~`` or ``~user``. Let's discuss each in turn. + +^^^^^^^^^^^^^^^^^^^^^^^^ +Spack Specific Variables +^^^^^^^^^^^^^^^^^^^^^^^^ + +Spack understands several special variables. These are: + + * ``$spack``: path to the prefix of this spack installation + * ``$tempdir``: default system temporary directory (as specified in + Python's `tempfile.tempdir + <https://docs.python.org/2/library/tempfile.html#tempfile.tempdir>`_ + variable. + * ``$user``: name of the current user + +Note that, as with shell variables, you can write these as ``$varname`` +or with braces to distinguish the variable from surrounding characters: +``${varname}``. Their names are also case insensitive meaning that ``$SPACK`` +works just as well as ``$spack``. These special variables are also +substituted first, so any environment variables with the same name will not +be used. + +^^^^^^^^^^^^^^^^^^^^^ +Environment Variables +^^^^^^^^^^^^^^^^^^^^^ + +Spack then uses ``os.path.expandvars`` to expand any remaining environment +variables. + +^^^^^^^^^^^^^^ +User Variables +^^^^^^^^^^^^^^ + +Spack also uses the ``os.path.expanduser`` function on the path to expand +any user tilde paths such as ``~`` or ``~user``. These tilde paths must appear +at the beginning of the path or ``os.path.expanduser`` will not properly +expand them. |