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author | Georg Brandl <georg@python.org> | 2007-08-15 14:28:22 (GMT) |
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committer | Georg Brandl <georg@python.org> | 2007-08-15 14:28:22 (GMT) |
commit | 116aa62bf54a39697e25f21d6cf6799f7faa1349 (patch) | |
tree | 8db5729518ed4ca88e26f1e26cc8695151ca3eb3 /Doc/library/site.rst | |
parent | 739c01d47b9118d04e5722333f0e6b4d0c8bdd9e (diff) | |
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Move the 3k reST doc tree in place.
Diffstat (limited to 'Doc/library/site.rst')
-rw-r--r-- | Doc/library/site.rst | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/Doc/library/site.rst b/Doc/library/site.rst new file mode 100644 index 0000000..4e54900 --- /dev/null +++ b/Doc/library/site.rst @@ -0,0 +1,87 @@ + +:mod:`site` --- Site-specific configuration hook +================================================ + +.. module:: site + :synopsis: A standard way to reference site-specific modules. + + +**This module is automatically imported during initialization.** The automatic +import can be suppressed using the interpreter's :option:`-S` option. + +.. index:: triple: module; search; path + +Importing this module will append site-specific paths to the module search path. + +.. index:: + pair: site-python; directory + pair: site-packages; directory + +It starts by constructing up to four directories from a head and a tail part. +For the head part, it uses ``sys.prefix`` and ``sys.exec_prefix``; empty heads +are skipped. For the tail part, it uses the empty string and then +:file:`lib/site-packages` (on Windows) or +:file:`lib/python|version|/site-packages` and then :file:`lib/site-python` (on +Unix and Macintosh). For each of the distinct head-tail combinations, it sees +if it refers to an existing directory, and if so, adds it to ``sys.path`` and +also inspects the newly added path for configuration files. + +A path configuration file is a file whose name has the form :file:`package.pth` +and exists in one of the four directories mentioned above; its contents are +additional items (one per line) to be added to ``sys.path``. Non-existing items +are never added to ``sys.path``, but no check is made that the item refers to a +directory (rather than a file). No item is added to ``sys.path`` more than +once. Blank lines and lines beginning with ``#`` are skipped. Lines starting +with ``import`` (followed by space or tab) are executed. + +.. versionchanged:: 2.6 + A space or tab is now required after the import keyword. + +.. index:: + single: package + triple: path; configuration; file + +For example, suppose ``sys.prefix`` and ``sys.exec_prefix`` are set to +:file:`/usr/local`. The Python X.Y library is then installed in +:file:`/usr/local/lib/python{X.Y}` (where only the first three characters of +``sys.version`` are used to form the installation path name). Suppose this has +a subdirectory :file:`/usr/local/lib/python{X.Y}/site-packages` with three +subsubdirectories, :file:`foo`, :file:`bar` and :file:`spam`, and two path +configuration files, :file:`foo.pth` and :file:`bar.pth`. Assume +:file:`foo.pth` contains the following:: + + # foo package configuration + + foo + bar + bletch + +and :file:`bar.pth` contains:: + + # bar package configuration + + bar + +Then the following directories are added to ``sys.path``, in this order:: + + /usr/local/lib/python2.3/site-packages/bar + /usr/local/lib/python2.3/site-packages/foo + +Note that :file:`bletch` is omitted because it doesn't exist; the :file:`bar` +directory precedes the :file:`foo` directory because :file:`bar.pth` comes +alphabetically before :file:`foo.pth`; and :file:`spam` is omitted because it is +not mentioned in either path configuration file. + +.. index:: module: sitecustomize + +After these path manipulations, an attempt is made to import a module named +:mod:`sitecustomize`, which can perform arbitrary site-specific customizations. +If this import fails with an :exc:`ImportError` exception, it is silently +ignored. + +.. index:: module: sitecustomize + +Note that for some non-Unix systems, ``sys.prefix`` and ``sys.exec_prefix`` are +empty, and the path manipulations are skipped; however the import of +:mod:`sitecustomize` is still attempted. + |