设置和使用 Python
CPython 解释器扫描命令行和各种设置的环境。
CPython 实现细节： 其它实现的命令行方案可能不同。见 替代实现 为进一步资源。
当援引 Python 时，可以指定这些任何选项：
python [-bBdEhiIOqsSuvVWx?] [-c command | -m module-name | script | - ] [args]
当然，最常见用例是简单援引脚本：
python myscript.py
The interpreter interface resembles that of the UNIX shell, but provides some additional methods of invocation:
When called with standard input connected to a tty device, it prompts for commands and executes them until an EOF (an end-of-file character, you can produce that with Ctrl - D on UNIX or Ctrl - Z, Enter on Windows) is read.
When called with a file name argument or with a file as standard input, it reads and executes a script from that file.
When called with a directory name argument, it reads and executes an appropriately named script from that directory.
当被调用采用 -c command , it executes the Python statement(s) given as 命令 . Here 命令 may contain multiple statements separated by newlines. Leading whitespace is significant in Python statements!
-c command
当被调用采用 -m module-name , the given module is located on the Python module path and executed as a script.
-m module-name
In non-interactive mode, the entire input is parsed before it is executed.
An interface option terminates the list of options consumed by the interpreter, all consecutive arguments will end up in sys.argv – note that the first element, subscript zero ( sys.argv[0] ), is a string reflecting the program’s source.
sys.argv
sys.argv[0]
执行 Python 代码在 命令 . 命令 可以是由换行符分隔的一条或多条语句，采用如正常模块代码中的显著前导空格。
若给出此选项，第一元素对于 sys.argv 将是 "-c" 且当前目录将被添加到起始在 sys.path (允许该目录下的模块被导入作为顶层模块)。
"-c"
sys.path
引发 审计事件 cpython.run_command 采用自变量 command .
cpython.run_command
command
搜索 sys.path for the named module and execute its contents as the __main__ 模块。
__main__
由于自变量是 模块 name, you must not give a file extension ( .py ). The module name should be a valid absolute Python module name, but the implementation may not always enforce this (e.g. it may allow you to use a name that includes a hyphen).
.py
Package names (including namespace packages) are also permitted. When a package name is supplied instead of a normal module, the interpreter will execute <pkg>.__main__ as the main module. This behaviour is deliberately similar to the handling of directories and zipfiles that are passed to the interpreter as the script argument.
<pkg>.__main__
注意
This option cannot be used with built-in modules and extension modules written in C, since they do not have Python module files. However, it can still be used for precompiled modules, even if the original source file is not available.
若给出此选项，第一元素对于 sys.argv will be the full path to the module file (while the module file is being located, the first element will be set to "-m" ). As with the -c option, the current directory will be added to the start of sys.path .
"-m"
-c
-I option can be used to run the script in isolated mode where sys.path contains neither the current directory nor the user’s site-packages directory. All PYTHON* environment variables are ignored, too.
-I
PYTHON*
Many standard library modules contain code that is invoked on their execution as a script. An example is the timeit 模块：
timeit
python -m timeit -s "setup here" "benchmarked code here" python -m timeit -h # for details
引发 审计事件 cpython.run_module 采用自变量 module-name .
cpython.run_module
module-name
另请参阅
runpy.run_module()
等效功能可直接用于 Python 代码
PEP 338 – 将模块作为脚本执行
3.1 版改变： 提供包名称以运行 __main__ 子模块。
3.4 版改变： 还支持名称空间包
读取命令从标准输入 ( sys.stdin )。若标准输入是终端， -i 是隐含的。
sys.stdin
-i
若给出此选项，第一元素对于 sys.argv 将是 "-" 且当前目录将被添加到起始在 sys.path .
"-"
引发 审计事件 cpython.run_stdin 不带自变量。
cpython.run_stdin
Execute the Python code contained in script , which must be a filesystem path (absolute or relative) referring to either a Python file, a directory containing a __main__.py file, or a zipfile containing a __main__.py 文件。
__main__.py
若给出此选项，第一元素对于 sys.argv 将是作为在命令行给出的脚本名称。
If the script name refers directly to a Python file, the directory containing that file is added to the start of sys.path , and the file is executed as the __main__ 模块。
If the script name refers to a directory or zipfile, the script name is added to the start of sys.path 和 __main__.py file in that location is executed as the __main__ 模块。
-I option can be used to run the script in isolated mode where sys.path 既不包含脚本目录，也不包含用户站点包目录。所有 PYTHON* environment variables are ignored, too.
引发 审计事件 cpython.run_file 采用自变量 filename .
cpython.run_file
filename
runpy.run_path()
若未给出接口选项， -i 是隐含的， sys.argv[0] 为空字符串 ( "" ) and the current directory will be added to the start of sys.path . Also, tab-completion and history editing is automatically enabled, if available on your platform (see readline 配置 ).
""
援引解释器
3.4 版改变： 自动启用 Tab 补全和历史编辑。
Print a short description of all command line options and corresponding environment variables and exit.
Print a short description of Python-specific environment variables and exit.
Added in version 3.11.
Print a description of implementation-specific -X options and exit.
-X
Print complete usage information and exit.
Print the Python version number and exit. Example output could be:
Python 3.8.0b2+
When given twice, print more information about the build, like:
Python 3.8.0b2+ (3.8:0c076caaa8, Apr 20 2019, 21:55:00) [GCC 6.2.0 20161005]
Added in version 3.6: The -VV 选项。
-VV
Issue a warning when converting bytes or bytearray to str without specifying encoding or comparing bytes or bytearray with str or bytes with int . Issue an error when the option is given twice ( -bb ).
bytes
bytearray
str
int
-bb
3.5 版改变： Affects also comparisons of bytes with int .
若给定，Python 不会试着写入 .pyc 文件当导入源模块时。另请参阅 PYTHONDONTWRITEBYTECODE .
.pyc
PYTHONDONTWRITEBYTECODE
Control the validation behavior of hash-based .pyc 文件。见 缓存字节码无效 。当设为 default , checked and unchecked hash-based bytecode cache files are validated according to their default semantics. When set to always , all hash-based .pyc files, whether checked or unchecked, are validated against their corresponding source file. When set to never , hash-based .pyc files are not validated against their corresponding source files.
default
always
never
The semantics of timestamp-based .pyc files are unaffected by this option.
Turn on parser debugging output (for expert only). See also the PYTHONDEBUG 环境变量。
PYTHONDEBUG
This option requires a debug build of Python , otherwise it’s ignored.
忽略所有 PYTHON* 环境变量，如 PYTHONPATH and PYTHONHOME ，可能有设置。
PYTHONPATH
PYTHONHOME
另请参阅 -P and -I (隔离) 选项。
-P
当传递脚本作为第一自变量或 -c option is used, enter interactive mode after executing the script or the command, even when sys.stdin does not appear to be a terminal. The PYTHONSTARTUP file is not read.
PYTHONSTARTUP
This can be useful to inspect global variables or a stack trace when a script raises an exception. See also PYTHONINSPECT .
PYTHONINSPECT
在隔离模式下运行 Python。这还隐含 -E , -P and -s 选项。
-E
-s
在隔离模式下 sys.path 既不包含脚本目录，也不包含用户站点包目录。所有 PYTHON* 环境变量也被忽略。可以施加进一步限定以阻止用户注入恶意代码。
Added in version 3.4.
移除 assert 语句和任何代码，若代码条件值为 __debug__ 。filename 自变量用于编译 ( bytecode ) 文件通过添加 .opt-1 先于 .pyc 扩展 (见 PEP 488 )。另请参阅 PYTHONOPTIMIZE .
__debug__
.opt-1
PYTHONOPTIMIZE
3.5 版改变： 修改 .pyc 文件名根据 PEP 488 .
Do -O 且还会丢弃 docstring (文档字符串)。filename 自变量用于编译 ( bytecode ) 文件通过添加 .opt-2 先于 .pyc 扩展 (见 PEP 488 ).
-O
.opt-2
不前置潜在不安全路径到 sys.path :
python -m module 命令行：不前置当前工作目录。
python -m module
python script.py 命令行：不前置脚本目录。若是符号链接，解析符号链接。
python script.py
python -c code and python (REPL) 命令行：前置空字符串，意味着当前工作目录。
python -c code
python
另请参阅 PYTHONSAFEPATH 环境变量，及 -E and -I (隔离) 选项。
PYTHONSAFEPATH
不显示版权和版本消息，即使在交互模式下。
Added in version 3.2.
Turn on hash randomization. This option only has an effect if the PYTHONHASHSEED environment variable is set to 0 , since hash randomization is enabled by default.
PYTHONHASHSEED
0
On previous versions of Python, this option turns on hash randomization, so that the __hash__() values of str and bytes objects are “salted” with an unpredictable random value. Although they remain constant within an individual Python process, they are not predictable between repeated invocations of Python.
__hash__()
Hash randomization is intended to provide protection against a denial-of-service caused by carefully chosen inputs that exploit the worst case performance of a dict construction, O ( n 2 ) complexity. See http://ocert.org/advisories/ocert-2011-003.html 了解细节。
PYTHONHASHSEED 允许为哈希种子保密设置固定值。
Added in version 3.2.3.
3.7 版改变： 选项不再被忽略。
不添加 user site-packages directory to sys.path .
user site-packages directory
另请参阅 PYTHONNOUSERSITE .
PYTHONNOUSERSITE
PEP 370 – 每用户站点包目录
禁用导入模块 site 和从属站点操纵 sys.path 牵涉的。还禁用这些操纵若 site 稍后被明确导入 (调用 site.main() 若想要触发它们)。
site
site.main()
强制 stdout 和 stderr 流无缓冲。此选项不影响 stdin 流。
另请参阅 PYTHONUNBUFFERED .
PYTHONUNBUFFERED
3.7 版改变： stdout 和 stderr 流的文本层现在是无缓冲的。
Print a message each time a module is initialized, showing the place (filename or built-in module) from which it is loaded. When given twice ( -vv ), print a message for each file that is checked for when searching for a module. Also provides information on module cleanup at exit.
-vv
3.10 版改变： The site module reports the site-specific paths and .pth files being processed.
.pth
另请参阅 PYTHONVERBOSE .
PYTHONVERBOSE
Warning control. Python’s warning machinery by default prints warning messages to sys.stderr .
sys.stderr
The simplest settings apply a particular action unconditionally to all warnings emitted by a process (even those that are otherwise ignored by default):
-Wdefault # Warn once per call location -Werror # Convert to exceptions -Walways # Warn every time -Wmodule # Warn once per calling module -Wonce # Warn once per Python process -Wignore # Never warn
The action names can be abbreviated as desired and the interpreter will resolve them to the appropriate action name. For example, -Wi 如同 -Wignore .
-Wi
-Wignore
The full form of argument is:
action:message:category:module:lineno
Empty fields match all values; trailing empty fields may be omitted. For example -W ignore::DeprecationWarning ignores all DeprecationWarning warnings.
-W ignore::DeprecationWarning
The action field is as explained above but only applies to warnings that match the remaining fields.
The message field must match the whole warning message; this match is case-insensitive.
The category field matches the warning category (ex: DeprecationWarning ). This must be a class name; the match test whether the actual warning category of the message is a subclass of the specified warning category.
DeprecationWarning
The 模块 field matches the (fully qualified) module name; this match is case-sensitive.
The lineno field matches the line number, where zero matches all line numbers and is thus equivalent to an omitted line number.
多 -W options can be given; when a warning matches more than one option, the action for the last matching option is performed. Invalid -W options are ignored (though, a warning message is printed about invalid options when the first warning is issued).
-W
Warnings can also be controlled using the PYTHONWARNINGS environment variable and from within a Python program using the warnings module. For example, the warnings.filterwarnings() function can be used to use a regular expression on the warning message.
PYTHONWARNINGS
warnings
warnings.filterwarnings()
见 警告过滤 and 描述警告过滤 了解更多细节。
Skip the first line of the source, allowing use of non-Unix forms of #!cmd . This is intended for a DOS specific hack only.
#!cmd
Reserved for various implementation-specific options. CPython currently defines the following possible values:
-X faulthandler 以启用 faulthandler 。另请参阅 PYTHONFAULTHANDLER .
-X faulthandler
faulthandler
PYTHONFAULTHANDLER
Added in version 3.3.
-X showrefcount to output the total reference count and number of used memory blocks when the program finishes or after each statement in the interactive interpreter. This only works on debug builds .
-X showrefcount
-X tracemalloc to start tracing Python memory allocations using the tracemalloc module. By default, only the most recent frame is stored in a traceback of a trace. Use -X tracemalloc=NFRAME to start tracing with a traceback limit of NFRAME frames. See tracemalloc.start() and PYTHONTRACEMALLOC 了解更多信息。
-X tracemalloc
tracemalloc
-X tracemalloc=NFRAME
tracemalloc.start()
PYTHONTRACEMALLOC
-X int_max_str_digits 配置 整数字符串转换长度局限性 。另请参阅 PYTHONINTMAXSTRDIGITS .
-X int_max_str_digits
PYTHONINTMAXSTRDIGITS
-X importtime to show how long each import takes. It shows module name, cumulative time (including nested imports) and self time (excluding nested imports). Note that its output may be broken in multi-threaded application. Typical usage is python3 -X importtime -c 'import asyncio' 。另请参阅 PYTHONPROFILEIMPORTTIME .
-X importtime
python3 -X importtime -c 'import asyncio'
PYTHONPROFILEIMPORTTIME
Added in version 3.7.
-X dev ：启用 Python 开发模式 , introducing additional runtime checks that are too expensive to be enabled by default. See also PYTHONDEVMODE .
-X dev
PYTHONDEVMODE
-X utf8 启用 Python UTF-8 模式 . -X utf8=0 明确禁用 Python UTF-8 模式 (even when it would otherwise activate automatically). See also PYTHONUTF8 .
-X utf8
-X utf8=0
PYTHONUTF8
-X pycache_prefix=PATH 启用写入 .pyc files to a parallel tree rooted at the given directory instead of to the code tree. See also PYTHONPYCACHEPREFIX .
-X pycache_prefix=PATH
PYTHONPYCACHEPREFIX
Added in version 3.8.
-X warn_default_encoding 发出 EncodingWarning when the locale-specific default encoding is used for opening files. See also PYTHONWARNDEFAULTENCODING .
-X warn_default_encoding
EncodingWarning
PYTHONWARNDEFAULTENCODING
Added in version 3.10.
-X no_debug_ranges disables the inclusion of the tables mapping extra location information (end line, start column offset and end column offset) to every instruction in code objects. This is useful when smaller code objects and pyc files are desired as well as suppressing the extra visual location indicators when the interpreter displays tracebacks. See also PYTHONNODEBUGRANGES .
-X no_debug_ranges
PYTHONNODEBUGRANGES
-X frozen_modules determines whether or not frozen modules are ignored by the import machinery. A value of “on” means they get imported and “off” means they are ignored. The default is “on” if this is an installed Python (the normal case). If it’s under development (running from the source tree) then the default is “off”. Note that the “importlib_bootstrap” and “importlib_bootstrap_external” frozen modules are always used, even if this flag is set to “off”.
-X frozen_modules
-X perf enables support for the Linux perf profiler. When this option is provided, the perf profiler will be able to report Python calls. This option is only available on some platforms and will do nothing if is not supported on the current system. The default value is “off”. See also PYTHONPERFSUPPORT and Python support for the Linux perf profiler .
-X perf
perf
PYTHONPERFSUPPORT
3.12 版添加。
It also allows passing arbitrary values and retrieving them through the sys._xoptions 字典。
sys._xoptions
3.9 版改变： 移除 -X showalloccount 选项。
-X showalloccount
3.10 版改变： 移除 -X oldparser 选项。
-X oldparser
预留为用于 Jython .
这些环境变量影响 Python 行为，它们的处理是在命令行开关前，而不是 -E 或 -I。习惯上，命令行开关覆写有冲突地方的环境变量。
更改标准 Python 库的位置。默认情况下，库的搜索是在 prefix/lib/pythonversion and exec_prefix/lib/pythonversion ，其中 prefix and exec_prefix 安装依赖目录，两者默认为 /usr/local .
prefix/lib/pythonversion
exec_prefix/lib/pythonversion
prefix
exec_prefix
/usr/local
当 PYTHONHOME 被设为单目录，它的值替换 prefix and exec_prefix 。要为这些指定不同值，设置 PYTHONHOME to prefix:exec_prefix .
prefix:exec_prefix
Augment the default search path for module files. The format is the same as the shell’s PATH : one or more directory pathnames separated by os.pathsep (e.g. colons on Unix or semicolons on Windows). Non-existent directories are silently ignored.
PATH
os.pathsep
In addition to normal directories, individual PYTHONPATH entries may refer to zipfiles containing pure Python modules (in either source or compiled form). Extension modules cannot be imported from zipfiles.
The default search path is installation dependent, but generally begins with prefix/lib/pythonversion (见 PYTHONHOME above). It is always appended to PYTHONPATH .
An additional directory will be inserted in the search path in front of PYTHONPATH as described above under 接口选项 . The search path can be manipulated from within a Python program as the variable sys.path .
若将这设为非空字符串，不前置潜在不安全路径到 sys.path ：见 -P 选项了解细节。
若把这设为非空字符串，它将覆写 sys.platlibdir 值。
sys.platlibdir
Added in version 3.9.
If this is the name of a readable file, the Python commands in that file are executed before the first prompt is displayed in interactive mode. The file is executed in the same namespace where interactive commands are executed so that objects defined or imported in it can be used without qualification in the interactive session. You can also change the prompts sys.ps1 and sys.ps2 and the hook sys.__interactivehook__ in this file.
sys.ps1
sys.ps2
sys.__interactivehook__
引发 审计事件 cpython.run_startup with the filename as the argument when called on startup.
cpython.run_startup
若将这设为非空字符串，相当于指定 -O 选项。若设为整数，相当于指定 -O 多次。
If this is set, it names a callable using dotted-path notation. The module containing the callable will be imported and then the callable will be run by the default implementation of sys.breakpointhook() which itself is called by built-in breakpoint() . If not set, or set to the empty string, it is equivalent to the value “pdb.set_trace”. Setting this to the string “0” causes the default implementation of sys.breakpointhook() to do nothing but return immediately.
sys.breakpointhook()
breakpoint()
若将这设为非空字符串，相当于指定 -d 选项。若设为整数，相当于指定 -d 多次。
-d
This environment variable requires a debug build of Python , otherwise it’s ignored.
若将这设为非空字符串，相当于指定 -i 选项。
此变量也可以被修改通过 Python 代码使用 os.environ 以强制审查模式，当程序终止时。
os.environ
若将这设为非空字符串，相当于指定 -u 选项。
-u
若将这设为非空字符串，相当于指定 -v 选项。若设为整数，相当于指定 -v 多次。
-v
若设置这，Python 忽略大小写在 import 语句。这只工作于 Windows 和 macOS。
import
If this is set to a non-empty string, Python won’t try to write .pyc files on the import of source modules. This is equivalent to specifying the -B 选项。
-B
若设置这，Python 将写入 .pyc files in a mirror directory tree at this path, instead of in __pycache__ directories within the source tree. This is equivalent to specifying the -X pycache_prefix=PATH 选项。
__pycache__
pycache_prefix=PATH
若此变量未设置或被设为 random , a random value is used to seed the hashes of str and bytes objects.
random
若 PYTHONHASHSEED is set to an integer value, it is used as a fixed seed for generating the hash() of the types covered by the hash randomization.
Its purpose is to allow repeatable hashing, such as for selftests for the interpreter itself, or to allow a cluster of python processes to share hash values.
The integer must be a decimal number in the range [0,4294967295]. Specifying the value 0 will disable hash randomization.
If this variable is set to an integer, it is used to configure the interpreter’s global 整数字符串转换长度局限性 .
若在运行解释器之前设置，这会覆盖用于 stdin/stdout/stderr 的编码，按句法 encodingname:errorhandler 。两者 encodingname 和 :errorhandler 部件是可选的，且拥有相同含义如在 str.encode() .
encodingname:errorhandler
encodingname
:errorhandler
str.encode()
对于 stderr， :errorhandler 部分被忽略；处理程序将始终为 'backslashreplace' .
'backslashreplace'
3.4 版改变： The encodingname 部分现在是可选的。
3.6 版改变： 在 Windows，交互控制台缓冲忽略由此变量指定的编码，除非 PYTHONLEGACYWINDOWSSTDIO 也有指定。透过标准流重定向的文件和管道不受影响。
PYTHONLEGACYWINDOWSSTDIO
若设置这，Python 将不添加 user site-packages directory to sys.path .
定义 user base directory , which is used to compute the path of the user site-packages directory and installation paths for python -m pip install --user .
user base directory
python -m pip install --user
若此环境变量有设置， sys.argv[0] will be set to its value instead of the value got through the C runtime. Only works on macOS.
这相当于 -W option. If set to a comma separated string, it is equivalent to specifying -W multiple times, with filters later in the list taking precedence over those earlier in the list.
PYTHONWARNINGS=default # Warn once per call location PYTHONWARNINGS=error # Convert to exceptions PYTHONWARNINGS=always # Warn every time PYTHONWARNINGS=module # Warn once per calling module PYTHONWARNINGS=once # Warn once per Python process PYTHONWARNINGS=ignore # Never warn
若此环境变量被设为非空字符串， faulthandler.enable() 被调用在启动时：安装处理程序为 SIGSEGV , SIGFPE , SIGABRT , SIGBUS and SIGILL 信号以转储 Python 回溯。这相当于 -X faulthandler 选项。
faulthandler.enable()
SIGSEGV
SIGFPE
SIGABRT
SIGBUS
SIGILL
若此环境变量被设为非空字符串，开始跟踪 Python 内存分配使用 tracemalloc 模块。变量的值是存储在跟踪回溯中的最大帧数。例如， PYTHONTRACEMALLOC=1 仅存储最近帧。见 tracemalloc.start() function for more information. This is equivalent to setting the -X tracemalloc 选项。
PYTHONTRACEMALLOC=1
If this environment variable is set to a non-empty string, Python will show how long each import takes. This is equivalent to setting the -X importtime 选项。
importtime
若此环境变量被设为非空字符串，启用 调试模式 的 asyncio 模块。
asyncio
设置 Python 内存分配器和/或安装调试挂钩。
设置 Python 使用的内存分配器系列：
default ：使用 默认内存分配器 .
malloc ：使用 malloc() C 库函数为所有域 （ PYMEM_DOMAIN_RAW , PYMEM_DOMAIN_MEM , PYMEM_DOMAIN_OBJ ).
malloc
malloc()
PYMEM_DOMAIN_RAW
PYMEM_DOMAIN_MEM
PYMEM_DOMAIN_OBJ
pymalloc ：使用 pymalloc 分配器 for PYMEM_DOMAIN_MEM and PYMEM_DOMAIN_OBJ domains and use the malloc() function for the PYMEM_DOMAIN_RAW domain.
pymalloc
安装 debug hooks :
debug ：将调试挂钩安装在顶部为 默认内存分配器 .
debug
malloc_debug ：如同 malloc 但还安装调试挂钩。
malloc_debug
pymalloc_debug ：如同 pymalloc 但还安装调试挂钩。
pymalloc_debug
Added in version 3.6.
3.7 版改变： 添加 "default" 分配器。
"default"
If set to a non-empty string, Python will print statistics of the pymalloc 内存分配器 每次创建新 pymalloc 对象 arena 时和关闭时。
This variable is ignored if the PYTHONMALLOC environment variable is used to force the malloc() allocator of the C library, or if Python is configured without pymalloc 支持。
PYTHONMALLOC
3.6 版改变： This variable can now also be used on Python compiled in release mode. It now has no effect if set to an empty string.
If set to a non-empty string, the default 文件系统编码和错误处理程序 mode will revert to their pre-3.6 values of ‘mbcs’ and ‘replace’, respectively. Otherwise, the new defaults ‘utf-8’ and ‘surrogatepass’ are used.
这也可以在运行时被启用采用 sys._enablelegacywindowsfsencoding() .
sys._enablelegacywindowsfsencoding()
可用性 ：Windows。
Added in version 3.6: 见 PEP 529 了解更多细节。
若设为非空字符串，不使用新的控制台读取器和写入器。这意味着 Unicode 字符将根据活动控制台代码页编码，而不是使用 UTF-8。
此变量被忽略，若标准流被重定向 (到文件或管道) 而不是引用控制台缓冲。
若设为值 0 ，导致主 Python 命令行应用程序跳过将传统基于 ASCII 的 C 和 POSIX 区域设置强制转换为能力更强基于 UTF-8 的替代。
若此变量 not set (or is set to a value other than 0 )， LC_ALL locale override environment variable is also not set, and the current locale reported for the LC_CTYPE category is either the default C locale, or else the explicitly ASCII-based POSIX locale, then the Python CLI will attempt to configure the following locales for the LC_CTYPE category in the order listed before loading the interpreter runtime:
LC_ALL
LC_CTYPE
C
POSIX
C.UTF-8
C.utf8
UTF-8
If setting one of these locale categories succeeds, then the LC_CTYPE environment variable will also be set accordingly in the current process environment before the Python runtime is initialized. This ensures that in addition to being seen by both the interpreter itself and other locale-aware components running in the same process (such as the GNU readline library), the updated setting is also seen in subprocesses (regardless of whether or not those processes are running a Python interpreter), as well as in operations that query the environment rather than the current C locale (such as Python’s own locale.getdefaultlocale() ).
readline
locale.getdefaultlocale()
Configuring one of these locales (either explicitly or via the above implicit locale coercion) automatically enables the surrogateescape 错误处理程序 for sys.stdin and sys.stdout ( sys.stderr 继续使用 backslashreplace as it does in any other locale). This stream handling behavior can be overridden using PYTHONIOENCODING as usual.
surrogateescape
sys.stdout
backslashreplace
PYTHONIOENCODING
For debugging purposes, setting PYTHONCOERCECLOCALE=warn will cause Python to emit warning messages on stderr if either the locale coercion activates, or else if a locale that would have triggered coercion is still active when the Python runtime is initialized.
PYTHONCOERCECLOCALE=warn
stderr
Also note that even when locale coercion is disabled, or when it fails to find a suitable target locale, PYTHONUTF8 will still activate by default in legacy ASCII-based locales. Both features must be disabled in order to force the interpreter to use ASCII 而不是 UTF-8 for system interfaces.
ASCII
可用性 ：Unix。
Added in version 3.7: 见 PEP 538 了解更多细节。
若此环境变量被设为非空字符串，启用 Python 开发模式 , introducing additional runtime checks that are too expensive to be enabled by default. This is equivalent to setting the -X dev 选项。
dev
若设为 1 ，启用 Python UTF-8 模式 .
1
若设为 0 ，禁用 Python UTF-8 模式 .
Setting any other non-empty string causes an error during interpreter initialisation.
If this environment variable is set to a non-empty string, issue a EncodingWarning when the locale-specific default encoding is used.
见 选择加入 EncodingWarning 了解细节。
If this variable is set, it disables the inclusion of the tables mapping extra location information (end line, start column offset and end column offset) to every instruction in code objects. This is useful when smaller code objects and pyc files are desired as well as suppressing the extra visual location indicators when the interpreter displays tracebacks.
If this variable is set to a nonzero value, it enables support for the Linux perf profiler so Python calls can be detected by it.
若设为 0 , disable Linux perf profiler support.
另请参阅 -X perf command-line option and Python support for the Linux perf profiler .
若设置，Python 将转储仍然存活的对象和引用计数在关闭解释器之后。
需要配置 Python 采用 --with-trace-refs 构建选项。
--with-trace-refs
If set, Python will dump objects and reference counts still alive after shutting down the interpreter into a file called FILENAME .
2. 在 Unix 平台使用 Python
键入搜索术语或模块、类、函数名称。