The CPython interpreter scans the command line and the environment for various settings.
CPython 實作細節： Other implementations' command line schemes may differ. See Alternate Implementations for further resources.
When invoking Python, you may specify any of these options:
python [-bBdEhiIOPqRsSuvVWx?] [-c command | -m module-name | script | - ] [args]
The most common use case is, of course, a simple invocation of a script:
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. For more on interactive mode, see 互動模式.
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.
When called with -c command, it executes the Python statement(s) given as
command. Here command may contain multiple statements separated by
newlines. Leading whitespace is significant in Python statements!
When called with -m module-name, the given module is located on the
Python module path and executed as a script.
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.
Execute the Python code in command. command can be one or more statements separated by newlines, with significant leading whitespace as in normal module code.
If this option is given, the first element of sys.argv will be
"-c" and the current directory will be added to the start of
sys.path (allowing modules in that directory to be imported as top
level modules).
引發一個附帶引數 command 的稽核事件 cpython.run_command。
Search sys.path for the named module and execute its contents as
the __main__ module.
Since the argument is a module 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).
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.
備註
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.
If this option is given, the first element of 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.
-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.
Many standard library modules contain code that is invoked on their execution
as a script. An example is the timeit module:
python -m timeit -s "setup here" "benchmarked code here"
python -m timeit -h # for details
引發一個附帶引數 module-name 的稽核事件 cpython.run_module。
也參考
runpy.run_module()Equivalent functionality directly available to Python code
PEP 338 -- Executing modules as scripts
在 3.1 版的變更: Supply the package name to run a __main__ submodule.
在 3.4 版的變更: namespace packages are also supported
Read commands from standard input (sys.stdin). If standard input is
a terminal, -i is implied.
If this option is given, the first element of sys.argv will be
"-" and the current directory will be added to the start of
sys.path.
引發一個不附帶引數的稽核事件 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 file.
If this option is given, the first element of sys.argv will be the
script name as given on the command line.
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__ module.
If the script name refers to a directory or zipfile, the script name is
added to the start of sys.path and the __main__.py file in
that location is executed as the __main__ module.
-I option can be used to run the script in isolated mode where
sys.path contains neither the script's directory nor the user's
site-packages directory. All PYTHON* environment variables are
ignored, too.
引發一個附帶引數 filename 的稽核事件 cpython.run_file。
也參考
runpy.run_path()Equivalent functionality directly available to Python code
If no interface option is given, -i is implied, sys.argv[0] is
an empty string ("") 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 configuration).
也參考
在 3.4 版的變更: Automatic enabling of tab-completion and history editing.
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.
在 3.11 版被加入.
印出完整使用資訊並離開。
在 3.11 版被加入.
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).
If given, Python won't try to write .pyc files on the
import of source modules. See also PYTHONDONTWRITEBYTECODE.
Control the validation behavior of hash-based .pyc files. See
Cached bytecode invalidation. When set to 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.
The semantics of timestamp-based .pyc files are unaffected by this
option.
Turn on parser debugging output (for expert only).
See also the PYTHONDEBUG environment variable.
This option requires a debug build of Python, otherwise it's ignored.
Ignore all PYTHON* environment variables, e.g.
PYTHONPATH and PYTHONHOME, that might be set.
Enter interactive mode after execution.
Using the -i option will enter interactive mode in any of the following circumstances:
Interactive mode will start even when sys.stdin does not appear to be a terminal. The
PYTHONSTARTUP file is not read.
This can be useful to inspect global variables or a stack trace when a script
raises an exception. See also PYTHONINSPECT.
Run Python in isolated mode. This also implies -E, -P
and -s options.
In isolated mode sys.path contains neither the script's directory nor
the user's site-packages directory. All PYTHON* environment
variables are ignored, too. Further restrictions may be imposed to prevent
the user from injecting malicious code.
在 3.4 版被加入.
Remove assert statements and any code conditional on the value of
__debug__. Augment the filename for compiled
(bytecode) files by adding .opt-1 before the .pyc
extension (see PEP 488). See also PYTHONOPTIMIZE.
在 3.5 版的變更: 根據 PEP 488 修改 .pyc 檔案名稱。
Do -O and also discard docstrings. Augment the filename
for compiled (bytecode) files by adding .opt-2 before the
.pyc extension (see PEP 488).
在 3.5 版的變更: 根據 PEP 488 修改 .pyc 檔案名稱。
Don't prepend a potentially unsafe path to sys.path:
python -m module command line: Don't prepend the current working
directory.
python script.py command line: Don't prepend the script's directory.
If it's a symbolic link, resolve symbolic links.
python -c code and python (REPL) command lines: Don't prepend an
empty string, which means the current working directory.
See also the PYTHONSAFEPATH environment variable, and -E
and -I (isolated) options.
在 3.11 版被加入.
Don't display the copyright and version messages even in interactive mode.
在 3.2 版被加入.
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.
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 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(n2) complexity. See http://ocert.org/advisories/ocert-2011-003.html for details.
PYTHONHASHSEED allows you to set a fixed value for the hash
seed secret.
在 3.2.3 版被加入.
在 3.7 版的變更: The option is no longer ignored.
Don't add the user site-packages directory to
sys.path.
另請參閱 PYTHONNOUSERSITE。
也參考
PEP 370 -- Per user site-packages directory
Disable the import of the module site and the site-dependent
manipulations of sys.path that it entails. Also disable these
manipulations if site is explicitly imported later (call
site.main() if you want them to be triggered).
Force the stdout and stderr streams to be unbuffered. This option has no effect on the stdin stream.
另請參閱 PYTHONUNBUFFERED。
在 3.7 版的變更: The text layer of the stdout and stderr streams now is unbuffered.
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.
在 3.10 版的變更: The site module reports the site-specific paths
and .pth files being processed.
另請參閱 PYTHONVERBOSE。
Warning control. Python's warning machinery by default prints warning
messages to 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
-Wall # Same as -Walways
-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 is the
same as -Wignore.
完整的引數形式為：
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.
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.
The module 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.
Multiple -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).
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.
See The Warnings Filter and Describing Warning Filters for more details.
Skip the first line of the source, allowing use of non-Unix forms of
#!cmd. This is intended for a DOS specific hack only.
Reserved for various implementation-specific options. CPython currently defines the following possible values:
-X faulthandler to enable faulthandler.
See also PYTHONFAULTHANDLER.
在 3.3 版被加入.
-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.
在 3.4 版被加入.
-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
for more information.
在 3.4 版被加入.
-X int_max_str_digits configures the integer string conversion
length limitation. See also
PYTHONINTMAXSTRDIGITS.
在 3.11 版被加入.
-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'. See also PYTHONPROFILEIMPORTTIME.
在 3.7 版被加入.
-X dev: enable Python Development Mode, introducing
additional runtime checks that are too expensive to be enabled by
default. See also PYTHONDEVMODE.
在 3.7 版被加入.
-X utf8 enables the Python UTF-8 Mode.
-X utf8=0 explicitly disables Python UTF-8 Mode
(even when it would otherwise activate automatically).
See also PYTHONUTF8.
在 3.7 版被加入.
-X pycache_prefix=PATH enables writing .pyc files to a parallel
tree rooted at the given directory instead of to the code tree. See also
PYTHONPYCACHEPREFIX.
在 3.8 版被加入.
-X warn_default_encoding issues a EncodingWarning when the
locale-specific default encoding is used for opening files.
See also PYTHONWARNDEFAULTENCODING.
在 3.10 版被加入.
-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.
在 3.11 版被加入.
-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. See also PYTHON_FROZEN_MODULES.
在 3.11 版被加入.
-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 對 Linux perf 分析器的支援.
在 3.12 版被加入.
-X perf_jit enables support for the Linux perf profiler with DWARF
support. When this option is provided, the perf profiler will be able
to report Python calls using DWARF information. 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 PYTHON_PERF_JIT_SUPPORT
and Python 對 Linux perf 分析器的支援.
在 3.13 版被加入.
-X cpu_count=n overrides os.cpu_count(),
os.process_cpu_count(), and multiprocessing.cpu_count().
n must be greater than or equal to 1.
This option may be useful for users who need to limit CPU resources of a
container system. See also PYTHON_CPU_COUNT.
If n is default, nothing is overridden.
在 3.13 版被加入.
-X presite=package.module specifies a module that should be
imported before the site module is executed and before the
__main__ module exists. Therefore, the imported module isn't
__main__. This can be used to execute code early during Python
initialization. Python needs to be built in debug mode
for this option to exist. See also PYTHON_PRESITE.
在 3.13 版被加入.
-X gil=0,1 forces the GIL to be disabled or enabled,
respectively. Setting to 0 is only available in builds configured with
--disable-gil. See also PYTHON_GIL and
Free-threaded CPython.
在 3.13 版被加入.
It also allows passing arbitrary values and retrieving them through the
sys._xoptions dictionary.
在 3.2 版被加入.
在 3.9 版的變更: 移除 -X showalloccount 選項。
在 3.10 版的變更: 移除 -X oldparser 選項。
The Python interpreter is configured by default to use colors to highlight output in certain situations such as when displaying tracebacks. This behavior can be controlled by setting different environment variables.
Setting the environment variable TERM to dumb will disable color.
If the FORCE_COLOR environment variable is set, then color will be
enabled regardless of the value of TERM. This is useful on CI systems which
aren’t terminals but can still display ANSI escape sequences.
If the NO_COLOR environment variable is set, Python will disable all color
in the output. This takes precedence over FORCE_COLOR.
All these environment variables are used also by other tools to control color
output. To control the color output only in the Python interpreter, the
PYTHON_COLORS environment variable can be used. This variable takes
precedence over NO_COLOR, which in turn takes precedence over
FORCE_COLOR.
These environment variables influence Python's behavior, they are processed before the command-line switches other than -E or -I. It is customary that command-line switches override environmental variables where there is a conflict.
Change the location of the standard Python libraries. By default, the
libraries are searched in prefix/lib/pythonversion and
exec_prefix/lib/pythonversion, where prefix and
exec_prefix are installation-dependent directories, both defaulting
to /usr/local.
When PYTHONHOME is set to a single directory, its value replaces
both prefix and exec_prefix. To specify different values
for these, set PYTHONHOME to 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.
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 (see 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
介面選項. The search path can be manipulated from
within a Python program as the variable sys.path.
If this is set to a non-empty string, don't prepend a potentially unsafe
path to sys.path: see the -P option for details.
在 3.11 版被加入.
If this is set to a non-empty string, it overrides the sys.platlibdir
value.
在 3.9 版被加入.
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.
引發一個附帶呼叫啟動時的檔案名稱為引數的稽核事件 cpython.run_startup。
If this is set to a non-empty string it is equivalent to specifying the
-O option. If set to an integer, it is equivalent to specifying
-O multiple times.
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.
在 3.7 版被加入.
If this is set to a non-empty string it is equivalent to specifying the
-d option. If set to an integer, it is equivalent to specifying
-d multiple times.
This environment variable requires a debug build of Python, otherwise it's ignored.
If this is set to a non-empty string it is equivalent to specifying the
-i option.
This variable can also be modified by Python code using os.environ
to force inspect mode on program termination.
引發一個不附帶引數的稽核事件 cpython.run_stdin。
在 3.12.5 版的變更: (also 3.11.10, 3.10.15, 3.9.20, and 3.8.20) Emits audit events.
在 3.13 版的變更: Uses PyREPL if possible, in which case PYTHONSTARTUP is
also executed. Emits audit events.
If this is set to a non-empty string it is equivalent to specifying the
-u option.
If this is set to a non-empty string it is equivalent to specifying the
-v option. If set to an integer, it is equivalent to specifying
-v multiple times.
If this is set, Python ignores case in import statements. This
only works on Windows and macOS.
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 option.
If this is set, Python will write .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 option.
在 3.8 版被加入.
If this variable is not set or set to random, a random value is used
to seed the hashes of str and bytes objects.
If 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.
在 3.2.3 版被加入.
If this variable is set to an integer, it is used to configure the interpreter's global integer string conversion length limitation.
在 3.11 版被加入.
If this is set before running the interpreter, it overrides the encoding used
for stdin/stdout/stderr, in the syntax encodingname:errorhandler. Both
the encodingname and the :errorhandler parts are optional and have
the same meaning as in str.encode().
For stderr, the :errorhandler part is ignored; the handler will always be
'backslashreplace'.
在 3.4 版的變更: The encodingname part is now optional.
在 3.6 版的變更: On Windows, the encoding specified by this variable is ignored for interactive
console buffers unless PYTHONLEGACYWINDOWSSTDIO is also specified.
Files and pipes redirected through the standard streams are not affected.
If this is set, Python won't add the user site-packages directory to sys.path.
也參考
PEP 370 -- Per user site-packages directory
Defines the 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.
也參考
PEP 370 -- Per user site-packages directory
If this environment variable is set, sys.argv[0] will be set to its
value instead of the value got through the C runtime. Only works on
macOS.
This is equivalent to the -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.
The simplest settings apply a particular action unconditionally to all warnings emitted by a process (even those that are otherwise ignored by default):
PYTHONWARNINGS=default # Warn once per call location
PYTHONWARNINGS=error # Convert to exceptions
PYTHONWARNINGS=always # Warn every time
PYTHONWARNINGS=all # Same as PYTHONWARNINGS=always
PYTHONWARNINGS=module # Warn once per calling module
PYTHONWARNINGS=once # Warn once per Python process
PYTHONWARNINGS=ignore # Never warn
See The Warnings Filter and Describing Warning Filters for more details.
If this environment variable is set to a non-empty string,
faulthandler.enable() is called at startup: install a handler for
SIGSEGV, SIGFPE,
SIGABRT, SIGBUS and
SIGILL signals to dump the Python traceback.
This is equivalent to -X faulthandler option.
在 3.3 版被加入.
If this environment variable is set to a non-empty string, start tracing
Python memory allocations using the tracemalloc module. The value of
the variable is the maximum number of frames stored in a traceback of a
trace. For example, PYTHONTRACEMALLOC=1 stores only the most recent
frame.
See the tracemalloc.start() function for more information.
This is equivalent to setting the -X tracemalloc option.
在 3.4 版被加入.
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 option.
在 3.7 版被加入.
If this environment variable is set to a non-empty string, enable the
debug mode of the asyncio module.
在 3.4 版被加入.
Set the Python memory allocators and/or install debug hooks.
Set the family of memory allocators used by Python:
default: use the default memory allocators.
malloc: use the malloc() function of the C library
for all domains (PYMEM_DOMAIN_RAW, PYMEM_DOMAIN_MEM,
PYMEM_DOMAIN_OBJ).
pymalloc: use the pymalloc allocator for
PYMEM_DOMAIN_MEM and PYMEM_DOMAIN_OBJ domains and use
the malloc() function for the PYMEM_DOMAIN_RAW domain.
mimalloc: use the mimalloc allocator for
PYMEM_DOMAIN_MEM and PYMEM_DOMAIN_OBJ domains and use
the malloc() function for the PYMEM_DOMAIN_RAW domain.
Install debug hooks:
debug: install debug hooks on top of the default memory
allocators.
malloc_debug: same as malloc but also install debug hooks.
pymalloc_debug: same as pymalloc but also install debug hooks.
mimalloc_debug: same as mimalloc but also install debug hooks.
在 3.6 版被加入.
在 3.7 版的變更: Added the "default" allocator.
If set to a non-empty string, Python will print statistics of the pymalloc memory allocator every time a new pymalloc object arena is created, and on shutdown.
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 support.
在 3.6 版的變更: 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 filesystem encoding and error handler mode will revert to their pre-3.6 values of 'mbcs' and 'replace', respectively. Otherwise, the new defaults 'utf-8' and 'surrogatepass' are used.
This may also be enabled at runtime with
sys._enablelegacywindowsfsencoding().
適用: Windows.
在 3.6 版被加入: 更多細節請見 PEP 529。
If set to a non-empty string, does not use the new console reader and writer. This means that Unicode characters will be encoded according to the active console code page, rather than using utf-8.
This variable is ignored if the standard streams are redirected (to files or pipes) rather than referring to console buffers.
適用: Windows.
在 3.6 版被加入.
If set to the value 0, causes the main Python command line application
to skip coercing the legacy ASCII-based C and POSIX locales to a more
capable UTF-8 based alternative.
If this variable is not set (or is set to a value other than 0), the
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:
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()).
Configuring one of these locales (either explicitly or via the above
implicit locale coercion) automatically enables the surrogateescape
error handler for sys.stdin and
sys.stdout (sys.stderr continues to use backslashreplace
as it does in any other locale). This stream handling behavior can be
overridden using PYTHONIOENCODING as usual.
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.
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 instead of UTF-8 for
system interfaces.
適用: Unix.
在 3.7 版被加入: 更多細節請見 PEP 538。
If this environment variable is set to a non-empty string, enable
Python Development Mode, introducing additional runtime
checks that are too expensive to be enabled by default.
This is equivalent to setting the -X dev option.
在 3.7 版被加入.
如果設為 1，則啟用 Python UTF-8 Mode。
如果設為 0，則停用 Python UTF-8 Mode。
Setting any other non-empty string causes an error during interpreter initialisation.
在 3.7 版被加入.
If this environment variable is set to a non-empty string, issue a
EncodingWarning when the locale-specific default encoding is used.
細節請見 選擇性加入的編碼警告。
在 3.10 版被加入.
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.
在 3.11 版被加入.
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.
If set to 0, disable Linux perf profiler support.
See also the -X perf command-line option
and Python 對 Linux perf 分析器的支援.
在 3.12 版被加入.
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
using DWARF information.
If set to 0, disable Linux perf profiler support.
See also the -X perf_jit command-line option
and Python 對 Linux perf 分析器的支援.
在 3.13 版被加入.
If this variable is set to a positive integer, it overrides the return
values of os.cpu_count() and os.process_cpu_count().
另請參閱 -X cpu_count 命令列選項。
在 3.13 版被加入.
If this variable is set to on or off, it 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
for non-debug builds (the normal case) and off for debug builds.
Note that the importlib_bootstrap and
importlib_bootstrap_external frozen modules are always used, even
if this flag is set to off.
另請參閱 -X frozen_modules 命令列選項。
在 3.13 版被加入.
If this variable is set to 1, the interpreter will colorize various kinds
of output. Setting it to 0 deactivates this behavior.
See also Controlling color.
在 3.13 版被加入.
If this variable is set to any value, the interpreter will not attempt to
load the Python-based REPL that requires curses and
readline, and will instead use the traditional parser-based
REPL.
在 3.13 版被加入.
This environment variable can be used to set the location of a
.python_history file (by default, it is .python_history in the
user's home directory).
在 3.13 版被加入.
If this variable is set to 1, the global interpreter lock (GIL) will be
forced on. Setting it to 0 forces the GIL off (needs Python configured with
the --disable-gil build option).
See also the -X gil command-line option, which takes
precedence over this variable, and Free-threaded CPython.
在 3.13 版被加入.
On builds where experimental just-in-time compilation is available, this
variable can force the JIT to be disabled (0) or enabled (1) at
interpreter startup.
在 3.13 版被加入.
If set, Python will dump objects and reference counts still alive after shutting down the interpreter.
Needs Python configured with the --with-trace-refs build option.
If set, Python will dump objects and reference counts still alive after shutting down the interpreter into a file under the path given as the value to this environment variable.
Needs Python configured with the --with-trace-refs build option.
在 3.11 版被加入.
If this variable is set to a module, that module will be imported
early in the interpreter lifecycle, before the site module is
executed, and before the __main__ module is created.
Therefore, the imported module is not treated as __main__.
This can be used to execute code early during Python initialization.
To import a submodule, use package.module as the value, like in
an import statement.
See also the -X presite command-line option,
which takes precedence over this variable.
Needs Python configured with the --with-pydebug build option.
在 3.13 版被加入.