1. Linha de comando e ambiente¶
O interpretador do CPython verifica a linha de comando e o ambiente em busca de várias configurações.
CPython implementation detail: Os esquemas de linha de comando de outras implementações podem ser diferentes. Consulte Implementações Alternativas para mais recursos.
1.1. Linha de comando¶
Ao invocar o Python, você pode especificar qualquer uma destas opções:
python [-bBdEhiIOqsSuvVWx?] [-c command | -m module-name | script | - ] [args]
O caso de uso mais comum é, obviamente, uma simples invocação de um script:
python myscript.py
1.1.1. Opções de interface¶
A interface do interpretador é semelhante à do console do UNIX, mas fornece alguns métodos adicionais de chamada:
Quando chamado com a entrada padrão conectada a um dispositivo tty, ele solicita comandos e os executa até um EOF (um caractere de fim de arquivo, você pode produzi-lo com Ctrl-D no UNIX ou Ctrl-Z, Enter no Windows) ser lido.
Quando chamado com um argumento de nome de arquivo ou com um arquivo como entrada padrão, ele lê e executa um script desse arquivo.
Quando chamado com um argumento de nome de diretório, ele lê e executa um script nomeado adequadamente desse diretório.
Quando chamado com
-c command
, ele executa as instruções Python fornecidas como command. Aqui command pode conter várias instruções separadas por novas linhas. O espaço em branco à esquerda é significativo nas instruções do Python!Quando chamado com
-m module-name
, o módulo fornecido está localizado no caminho do módulo Python e é executado como um script.
No modo não interativo, toda a entrada é analisada antes de ser executada.
Uma opção de interface termina a lista de opções consumidas pelo interpretador, todos os argumentos consecutivos terminam em sys.argv
– observe que o primeiro elemento, subscrito zero (sys.argv[0]
) , é uma string que reflete a fonte do programa.
-
-c
<command>
¶ Executa o código Python em command. command pode ser uma ou mais instruções separadas por novas linhas, com espaços em branco à esquerda significativos, como no código normal do módulo.
Se esta opção for fornecida, o primeiro elemento de
sys.argv
será"-c"
e o diretório atual será adicionado ao início desys.path
(permitindo módulos nesse diretório para ser importado como módulos de nível superior).Levanta um evento de auditoria
cpython.run_command
com argumentocommand
.
-
-m
<module-name>
¶ Procura
sys.path
pelo módulo nomeado e executa seu conteúdo como o módulo__main__
.Como o argumento é um nome de module, você não deve fornecer uma extensão de arquivo (
.py
). O nome do módulo deve ser um nome de módulo Python absoluto válido, mas a implementação nem sempre pode impor isso (por exemplo, pode permitir que você use um nome que inclua um hífen).Nomes de pacotes (incluindo pacotes de espaço de nomes) também são permitidos. Quando um nome de pacote é fornecido ao invés de um módulo normal, o interpretador irá executar
<pkg>.__main__
como o módulo principal. Esse comportamento é deliberadamente semelhante ao tratamento de diretórios e arquivos zip que são passados para o interpretador como o argumento do script.Nota
Esta opção não pode ser usada com módulos embutidos e módulos de extensão escritos em C, uma vez que eles não possuem arquivos de módulo Python. No entanto, ele ainda pode ser usado para módulos pré-compilados, mesmo se o arquivo fonte original não estiver disponível.
Se esta opção for fornecida, o primeiro elemento de
sys.argv
será o caminho completo para o arquivo do módulo (enquanto o arquivo do módulo está sendo localizado, o primeiro elemento será definido como"-m"
). Como com a opção-c
, o diretório atual será adicionado ao início desys.path
.A opção
-I
pode ser usada para executar o script em modo isolado ondesys.path
não contém nem o diretório atual nem o diretório de pacotes de sites do usuário. Todas as variáveis de ambientePYTHON*
são ignoradas também.Muitos módulos de biblioteca padrão contêm código que é chamado em sua execução como um script. Um exemplo é o módulo
timeit
:python -m timeit -s 'setup here' 'benchmarked code here' python -m timeit -h # for details
Levanta um evento de auditoria
cpython.run_module
com argumentomodule-name
.Ver também
runpy.run_module()
Funcionalidade equivalente diretamente disponível para o código Python
PEP 338 – Executando módulos como scripts
Alterado na versão 3.1: Forneça o nome do pacote para executar um submódulo
__main__
.Alterado na versão 3.4: pacotes de espaço de nomes também são suportados
-
-
Lê os comandos da entrada padrão (
sys.stdin
). Se a entrada padrão for um terminal,-i
está implícito.Se esta opção for fornecida, o primeiro elemento de
sys.argv
será"-"
e o diretório atual será adicionado ao início desys.path
.Levanta um evento de auditoria
cpython.run_stdin
com nenhum argumento.
-
<script>
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 wheresys.path
contains neither the script’s directory nor the user’s site-packages directory. AllPYTHON*
environment variables are ignored, too.Raises an auditing event
cpython.run_file
with argumentfilename
.Ver também
runpy.run_path()
Funcionalidade equivalente diretamente disponível para o código Python
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
Configuração Readline).
Ver também
Alterado na versão 3.4: Automatic enabling of tab-completion and history editing.
1.1.2. Opções genéricas¶
1.1.3. Miscellaneous options¶
-
-b
¶
Issue a warning when comparing
bytes
orbytearray
withstr
orbytes
withint
. Issue an error when the option is given twice (-bb
).
-
-B
¶
If given, Python won’t try to write
.pyc
files on the import of source modules. See alsoPYTHONDONTWRITEBYTECODE
.
-
--check-hash-based-pycs
default|always|never
¶ Control the validation behavior of hash-based
.pyc
files. See Cached bytecode invalidation. When set todefault
, checked and unchecked hash-based bytecode cache files are validated according to their default semantics. When set toalways
, all hash-based.pyc
files, whether checked or unchecked, are validated against their corresponding source file. When set tonever
, hash-based.pyc
files are not validated against their corresponding source files.The semantics of timestamp-based
.pyc
files are unaffected by this option.
-
-d
¶
Turn on parser debugging output (for expert only, depending on compilation options). See also
PYTHONDEBUG
.
-
-E
¶
Ignore all
PYTHON*
environment variables, e.g.PYTHONPATH
andPYTHONHOME
, that might be set.
-
-i
¶
When a script is passed as first argument or the
-c
option is used, enter interactive mode after executing the script or the command, even whensys.stdin
does not appear to be a terminal. ThePYTHONSTARTUP
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
.
-
-I
¶
Run Python in isolated mode. This also implies -E and -s. In isolated mode
sys.path
contains neither the script’s directory nor the user’s site-packages directory. AllPYTHON*
environment variables are ignored, too. Further restrictions may be imposed to prevent the user from injecting malicious code.Novo na versão 3.4.
-
-O
¶
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 alsoPYTHONOPTIMIZE
.Alterado na versão 3.5: Modify
.pyc
filenames according to PEP 488.
-
-OO
¶
Do
-O
and also discard docstrings. Augment the filename for compiled (bytecode) files by adding.opt-2
before the.pyc
extension (see PEP 488).Alterado na versão 3.5: Modify
.pyc
filenames according to PEP 488.
-
-q
¶
Não exibe as mensagens de copyright e de versão nem mesmo no modo interativo.
Novo na versão 3.2.
-
-R
¶
Turn on hash randomization. This option only has an effect if the
PYTHONHASHSEED
environment variable is set to0
, 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(n^2) complexity. See http://www.ocert.org/advisories/ocert-2011-003.html for details.
PYTHONHASHSEED
allows you to set a fixed value for the hash seed secret.Alterado na versão 3.7: A opção não é mais ignorada.
Novo na versão 3.2.3.
-
-s
¶
Don’t add the
user site-packages directory
tosys.path
.Ver também
PEP 370 – Per user site-packages directory
-
-S
¶
Disable the import of the module
site
and the site-dependent manipulations ofsys.path
that it entails. Also disable these manipulations ifsite
is explicitly imported later (callsite.main()
if you want them to be triggered).
-
-u
¶
Force the stdout and stderr streams to be unbuffered. This option has no effect on the stdin stream.
See also
PYTHONUNBUFFERED
.Alterado na versão 3.7: The text layer of the stdout and stderr streams now is unbuffered.
-
-v
¶
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. See alsoPYTHONVERBOSE
.
-
-W
arg
¶ Warning control. Python’s warning machinery by default prints warning messages to
sys.stderr
. A typical warning message has the following form:file:line: category: message
By default, each warning is printed once for each source line where it occurs. This option controls how often warnings are printed.
Multiple
-W
options may 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 thewarnings
module.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 (e.g.
-Wi
,-Wd
,-Wa
,-We
) and the interpreter will resolve them to the appropriate action name.See The Warnings Filter and Describing Warning Filters for more details.
-
-x
¶
Skip the first line of the source, allowing use of non-Unix forms of
#!cmd
. This is intended for a DOS specific hack only.
-
-X
¶
Reserved for various implementation-specific options. CPython currently defines the following possible values:
-X faulthandler
to enablefaulthandler
;-X oldparser
: enable the traditional LL(1) parser. See alsoPYTHONOLDPARSER
and PEP 617.-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 tracemalloc
to start tracing Python memory allocations using thetracemalloc
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 thetracemalloc.start()
for more information.-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 ispython3 -X importtime -c 'import asyncio'
. See alsoPYTHONPROFILEIMPORTTIME
.-X dev
: enable Python Development Mode, introducing additional runtime checks that are too expensive to be enabled by default.-X utf8
enables UTF-8 mode for operating system interfaces, overriding the default locale-aware mode.-X utf8=0
explicitly disables UTF-8 mode (even when it would otherwise activate automatically). SeePYTHONUTF8
for more details.-X pycache_prefix=PATH
enables writing.pyc
files to a parallel tree rooted at the given directory instead of to the code tree. See alsoPYTHONPYCACHEPREFIX
.
It also allows passing arbitrary values and retrieving them through the
sys._xoptions
dictionary.Alterado na versão 3.2: The
-X
option was added.Novo na versão 3.3: The
-X faulthandler
option.Novo na versão 3.4: The
-X showrefcount
and-X tracemalloc
options.Novo na versão 3.6: The
-X showalloccount
option.Novo na versão 3.7: The
-X importtime
,-X dev
and-X utf8
options.Novo na versão 3.8: The
-X pycache_prefix
option. The-X dev
option now logsclose()
exceptions inio.IOBase
destructor.Alterado na versão 3.9: Using
-X dev
option, check encoding and errors arguments on string encoding and decoding operations.The
-X showalloccount
option has been removed.Deprecated since version 3.9, will be removed in version 3.10: The
-X oldparser
option.
1.2. Environment variables¶
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.
-
PYTHONHOME
¶ Change the location of the standard Python libraries. By default, the libraries are searched in
prefix/lib/pythonversion
andexec_prefix/lib/pythonversion
, whereprefix
andexec_prefix
are installation-dependent directories, both defaulting to/usr/local
.When
PYTHONHOME
is set to a single directory, its value replaces bothprefix
andexec_prefix
. To specify different values for these, setPYTHONHOME
toprefix:exec_prefix
.
-
PYTHONPATH
¶ Augment the default search path for module files. The format is the same as the shell’s
PATH
: one or more directory pathnames separated byos.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
(seePYTHONHOME
above). It is always appended toPYTHONPATH
.An additional directory will be inserted in the search path in front of
PYTHONPATH
as described above under Opções de interface. The search path can be manipulated from within a Python program as the variablesys.path
.
-
PYTHONPLATLIBDIR
¶ If this is set to a non-empty string, it overrides the
sys.platlibdir
value.Novo na versão 3.9.
-
PYTHONSTARTUP
¶ 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
andsys.ps2
and the hooksys.__interactivehook__
in this file.Raises an auditing event
cpython.run_startup
with the filename as the argument when called on startup.
-
PYTHONOPTIMIZE
¶ 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.
-
PYTHONBREAKPOINT
¶ 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-inbreakpoint()
. 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 ofsys.breakpointhook()
to do nothing but return immediately.Novo na versão 3.7.
-
PYTHONDEBUG
¶ 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.
-
PYTHONOLDPARSER
¶ If this is set to a non-empty string, enable the traditional LL(1) parser.
See also the
-X
oldparser
option and PEP 617.Deprecated since version 3.9, will be removed in version 3.10.
-
PYTHONINSPECT
¶ 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.
-
PYTHONUNBUFFERED
¶ If this is set to a non-empty string it is equivalent to specifying the
-u
option.
-
PYTHONVERBOSE
¶ 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.
-
PYTHONCASEOK
¶ If this is set, Python ignores case in
import
statements. This only works on Windows and OS X.
-
PYTHONDONTWRITEBYTECODE
¶ 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.
-
PYTHONPYCACHEPREFIX
¶ 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.Novo na versão 3.8.
-
PYTHONHASHSEED
¶ 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.
Novo na versão 3.2.3.
-
PYTHONIOENCODING
¶ If this is set before running the interpreter, it overrides the encoding used for stdin/stdout/stderr, in the syntax
encodingname:errorhandler
. Both theencodingname
and the:errorhandler
parts are optional and have the same meaning as instr.encode()
.For stderr, the
:errorhandler
part is ignored; the handler will always be'backslashreplace'
.Alterado na versão 3.4: The
encodingname
part is now optional.Alterado na versão 3.6: 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.
-
PYTHONNOUSERSITE
¶ If this is set, Python won’t add the
user site-packages directory
tosys.path
.Ver também
PEP 370 – Per user site-packages directory
-
PYTHONUSERBASE
¶ Defines the
user base directory
, which is used to compute the path of theuser site-packages directory
and Distutils installation paths forpython setup.py install --user
.Ver também
PEP 370 – Per user site-packages directory
-
PYTHONEXECUTABLE
¶ 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 Mac OS X.
-
PYTHONWARNINGS
¶ 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=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.
-
PYTHONFAULTHANDLER
¶ If this environment variable is set to a non-empty string,
faulthandler.enable()
is called at startup: install a handler forSIGSEGV
,SIGFPE
,SIGABRT
,SIGBUS
andSIGILL
signals to dump the Python traceback. This is equivalent to-X
faulthandler
option.Novo na versão 3.3.
-
PYTHONTRACEMALLOC
¶ 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 thetracemalloc.start()
for more information.Novo na versão 3.4.
-
PYTHONPROFILEIMPORTTIME
¶ If this environment variable is set to a non-empty string, Python will show how long each import takes. This is exactly equivalent to setting
-X importtime
on the command line.Novo na versão 3.7.
-
PYTHONASYNCIODEBUG
¶ If this environment variable is set to a non-empty string, enable the debug mode of the
asyncio
module.Novo na versão 3.4.
-
PYTHONMALLOC
¶ 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 themalloc()
function of the C library for all domains (PYMEM_DOMAIN_RAW
,PYMEM_DOMAIN_MEM
,PYMEM_DOMAIN_OBJ
).pymalloc
: use the pymalloc allocator forPYMEM_DOMAIN_MEM
andPYMEM_DOMAIN_OBJ
domains and use themalloc()
function for thePYMEM_DOMAIN_RAW
domain.
Install debug hooks:
debug
: install debug hooks on top of the default memory allocators.malloc_debug
: same asmalloc
but also install debug hooks.pymalloc_debug
: same aspymalloc
but also install debug hooks.
See the default memory allocators and the
PyMem_SetupDebugHooks()
function (install debug hooks on Python memory allocators).Alterado na versão 3.7: Added the
"default"
allocator.Novo na versão 3.6.
-
PYTHONMALLOCSTATS
¶ 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 themalloc()
allocator of the C library, or if Python is configured withoutpymalloc
support.Alterado na versão 3.6: This variable can now also be used on Python compiled in release mode. It now has no effect if set to an empty string.
-
PYTHONLEGACYWINDOWSFSENCODING
¶ If set to a non-empty string, the default filesystem encoding and errors 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()
.Disponibilidade: Windows.
Novo na versão 3.6: Veja PEP 529 para mais detalhes.
-
PYTHONLEGACYWINDOWSSTDIO
¶ 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.
Disponibilidade: Windows.
Novo na versão 3.6.
-
PYTHONCOERCECLOCALE
¶ 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
), theLC_ALL
locale override environment variable is also not set, and the current locale reported for theLC_CTYPE
category is either the defaultC
locale, or else the explicitly ASCII-basedPOSIX
locale, then the Python CLI will attempt to configure the following locales for theLC_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 GNUreadline
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 ownlocale.getdefaultlocale()
).Configuring one of these locales (either explicitly or via the above implicit locale coercion) automatically enables the
surrogateescape
error handler forsys.stdin
andsys.stdout
(sys.stderr
continues to usebackslashreplace
as it does in any other locale). This stream handling behavior can be overridden usingPYTHONIOENCODING
as usual.For debugging purposes, setting
PYTHONCOERCECLOCALE=warn
will cause Python to emit warning messages onstderr
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 useASCII
instead ofUTF-8
for system interfaces.Availability: *nix.
Novo na versão 3.7: See PEP 538 for more details.
-
PYTHONDEVMODE
¶ 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.
Novo na versão 3.7.
-
PYTHONUTF8
¶ If set to
1
, enables the interpreter’s UTF-8 mode, whereUTF-8
is used as the text encoding for system interfaces, regardless of the current locale setting.This means that:
sys.getfilesystemencoding()
returns'UTF-8'
(the locale encoding is ignored).locale.getpreferredencoding()
returns'UTF-8'
(the locale encoding is ignored, and the function’sdo_setlocale
parameter has no effect).sys.stdin
,sys.stdout
, andsys.stderr
all use UTF-8 as their text encoding, with thesurrogateescape
error handler being enabled forsys.stdin
andsys.stdout
(sys.stderr
continues to usebackslashreplace
as it does in the default locale-aware mode)
As a consequence of the changes in those lower level APIs, other higher level APIs also exhibit different default behaviours:
Command line arguments, environment variables and filenames are decoded to text using the UTF-8 encoding.
os.fsdecode()
andos.fsencode()
use the UTF-8 encoding.open()
,io.open()
, andcodecs.open()
use the UTF-8 encoding by default. However, they still use the strict error handler by default so that attempting to open a binary file in text mode is likely to raise an exception rather than producing nonsense data.
Note that the standard stream settings in UTF-8 mode can be overridden by
PYTHONIOENCODING
(just as they can be in the default locale-aware mode).If set to
0
, the interpreter runs in its default locale-aware mode.Setting any other non-empty string causes an error during interpreter initialisation.
If this environment variable is not set at all, then the interpreter defaults to using the current locale settings, unless the current locale is identified as a legacy ASCII-based locale (as described for
PYTHONCOERCECLOCALE
), and locale coercion is either disabled or fails. In such legacy locales, the interpreter will default to enabling UTF-8 mode unless explicitly instructed not to do so.Also available as the
-X
utf8
option.Novo na versão 3.7: See PEP 540 for more details.
1.2.1. Debug-mode variables¶
Setting these variables only has an effect in a debug build of Python.
-
PYTHONTHREADDEBUG
¶ If set, Python will print threading debug info.
Need Python configured with the
--with-pydebug
build option.
-
PYTHONDUMPREFS
¶ If set, Python will dump objects and reference counts still alive after shutting down the interpreter.
Need Python configured with the
--with-trace-refs
build option.