28.14. site
—— 指定 Site 的配置钩子¶
源代码: Lib/site.py
这个模块将在初始化时被自动导入。 此自动导入可以通过使用解释器的 -S
选项来屏蔽。
Importing this module will append site-specific paths to the module search path and add a few builtins.
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
lib/site-packages
(on Windows) or
lib/pythonX.Y/site-packages
and then 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.
一个路径配置文件是具有 name.pth
命名格式的文件,并且存在上面提到的四个目录之一中;它的内容是要添加到 sys.path
中的额外项目(每行一个)。不存在的项目不会添加到 sys.path
,并且不会检查项目指向的是目录还是文件。项目不会被添加到 sys.path
超过一次。空行和由 #
起始的行会被跳过。以 import
开始的行(跟着空格或 TAB)会被执行。
在 2.6 版更改: A space or tab is now required after the import keyword.
例如,假设 sys.prefix
和 sys.exec_prefix
已经被设置为 /usr/local
。 Python X.Y 的库之后被安装为 /usr/local/lib/pythonX.Y
。假设有一个拥有三个孙目录 foo
, bar
和 spam
的子目录 /usr/local/lib/pythonX.Y/site-packages
,并且有两个路径配置文件 foot.pth
和 bar.pth
。假定 foo.pth
内容如下:
# foo package configuration
foo
bar
bletch
并且 bar.pth
包含:
# bar package configuration
bar
则下面特定版目录将以如下顺序被添加到 sys.path
。
/usr/local/lib/pythonX.Y/site-packages/bar
/usr/local/lib/pythonX.Y/site-packages/foo
Note that bletch
is omitted because it doesn’t exist; the bar
directory precedes the foo
directory because bar.pth
comes
alphabetically before foo.pth
; and spam
is omitted because it is
not mentioned in either path configuration file.
After these path manipulations, an attempt is made to import a module named
sitecustomize
, which can perform arbitrary site-specific customizations.
It is typically created by a system administrator in the site-packages
directory. If this import fails with an ImportError
exception, it is
silently ignored. If Python is started without output streams available, as
with pythonw.exe
on Windows (which is used by default to start IDLE),
attempted output from sitecustomize
is ignored. Any exception other
than ImportError
causes a silent and perhaps mysterious failure of the
process.
After this, an attempt is made to import a module named usercustomize
,
which can perform arbitrary user-specific customizations, if
ENABLE_USER_SITE
is true. This file is intended to be created in the
user site-packages directory (see below), which is part of sys.path
unless
disabled by -s
. An ImportError
will be silently ignored.
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
sitecustomize
and usercustomize
is still attempted.
-
site.
PREFIXES
¶ A list of prefixes for site-packages directories.
2.6 新版功能.
-
site.
ENABLE_USER_SITE
¶ Flag showing the status of the user site-packages directory.
True
means that it is enabled and was added tosys.path
.False
means that it was disabled by user request (with-s
orPYTHONNOUSERSITE
).None
means it was disabled for security reasons (mismatch between user or group id and effective id) or by an administrator.2.6 新版功能.
-
site.
USER_SITE
¶ Path to the user site-packages for the running Python. Can be
None
ifgetusersitepackages()
hasn’t been called yet. Default value is~/.local/lib/pythonX.Y/site-packages
for UNIX and non-framework Mac OS X builds,~/Library/Python/X.Y/lib/python/site-packages
for Mac framework builds, and%APPDATA%\Python\PythonXY\site-packages
on Windows. This directory is a site directory, which means that.pth
files in it will be processed.2.6 新版功能.
-
site.
USER_BASE
¶ Path to the base directory for the user site-packages. Can be
None
ifgetuserbase()
hasn’t been called yet. Default value is~/.local
for UNIX and Mac OS X non-framework builds,~/Library/Python/X.Y
for Mac framework builds, and%APPDATA%\Python
for Windows. This value is used by Distutils to compute the installation directories for scripts, data files, Python modules, etc. for the user installation scheme. See alsoPYTHONUSERBASE
.2.6 新版功能.
-
site.
addsitedir
(sitedir, known_paths=None)¶ Add a directory to sys.path and process its
.pth
files. Typically used insitecustomize
orusercustomize
(see above).
-
site.
getsitepackages
()¶ Return a list containing all global site-packages directories (and possibly site-python).
2.7 新版功能.
-
site.
getuserbase
()¶ Return the path of the user base directory,
USER_BASE
. If it is not initialized yet, this function will also set it, respectingPYTHONUSERBASE
.2.7 新版功能.
-
site.
getusersitepackages
()¶ Return the path of the user-specific site-packages directory,
USER_SITE
. If it is not initialized yet, this function will also set it, respectingPYTHONNOUSERSITE
andUSER_BASE
.2.7 新版功能.
The site
module also provides a way to get the user directories from the
command line:
$ python -m site --user-site
/home/user/.local/lib/python2.7/site-packages
If it is called without arguments, it will print the contents of
sys.path
on the standard output, followed by the value of
USER_BASE
and whether the directory exists, then the same thing for
USER_SITE
, and finally the value of ENABLE_USER_SITE
.
-
--user-base
¶
Print the path to the user base directory.
-
--user-site
¶
Print the path to the user site-packages directory.
If both options are given, user base and user site will be printed (always in
this order), separated by os.pathsep
.
If any option is given, the script will exit with one of these values: 0
if
the user site-packages directory is enabled, 1
if it was disabled by the
user, 2
if it is disabled for security reasons or by an administrator, and a
value greater than 2 if there is an error.
参见
PEP 370 – 分用户的 site-packages 目录