library/site
site
—— 指定域的配置钩子¶
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。
导入此模块将会附加域特定的路径到模块搜索路径并且添加一些内建对象,除非使用了 -S
选项。在此例中,模块可以被安全地导入,而不会对模块搜索路径和内建对象有自动的修改或添加。要明确地触发通常域特定的添加,调用函数 site.main()
。
在 3.3 版更改: 即便使用了 -S
,也会导入此模块用于触发路径操纵。
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
(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.
在 3.5 版更改: Support for the "site-python" directory has been removed.
如果名为 "pyvenv.cfg" 的文件存在于 sys.executable 之上的一个目录中,则 sys.prefix 和 sys.exec_prefix 将被设置为该目录,并且还会检查 site-packages ( sys.base_prefix 和 sys.base_exec_prefix 始终是 Python 安装的 "真实" 前缀)。 如果 "pyvenv.cfg" (引导程序配置文件)包含设置为非 "true"(不区分大小写)的 "include-system-site-packages" 键,则不会在系统级前缀中搜索 site-packages;反之则会。
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。
注解
每次启动 Python,在 .pth
文件中的可执行行都将会被运行,而不管特定的模块实际上是否需要被使用。 因此,其影响应降至最低。可执行行的主要预期目的是使相关模块可导入(加载第三方导入钩子,调整 PATH
等)。如果它发生了,任何其他的初始化都应当在模块实际导入之前完成。将代码块限制为一行是一种有意采取的措施,不鼓励在此处放置更复杂的内容。
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
or its subclass
exception, and the exception's name
attribute equals to 'sitecustomize'
,
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 other exception
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
. If this import fails with an ImportError
or
its subclass exception, and the exception's name
attribute equals to
'usercustomize'
, it is 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.
Readline configuration¶
On systems that support readline
, this module will also import and
configure the rlcompleter
module, if Python is started in
interactive mode and without the -S
option.
The default behavior is enable tab-completion and to use
~/.python_history
as the history save file. To disable it, delete (or
override) the sys.__interactivehook__
attribute in your
sitecustomize
or usercustomize
module or your
PYTHONSTARTUP
file.
在 3.4 版更改: Activation of rlcompleter and history was made automatic.
模块内容¶
-
site.
PREFIXES
¶ A list of prefixes for site-packages directories.
-
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.
-
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.
-
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
.
-
site.
main
()¶ Adds all the standard site-specific directories to the module search path. This function is called automatically when this module is imported, unless the Python interpreter was started with the
-S
flag.在 3.3 版更改: This function used to be called unconditionally.
-
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.
3.2 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
.3.2 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, respectingUSER_BASE
. To determine if the user-specific site-packages was added tosys.path
ENABLE_USER_SITE
should be used.3.2 新版功能.
命令行界面¶
The site
module also provides a way to get the user directories from the
command line:
$ python3 -m site --user-site
/home/user/.local/lib/python3.3/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
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