.B \-q
]
[
+.B \-R
+]
+[
.B \-O
]
[
Do not print the version and copyright messages. These messages are
also suppressed in non-interactive mode.
.TP
+.B \-R
+Turn on hash randomization. This option only has an effect if the
+\fBPYTHONHASHSEED\fR environment variable is set to \fB0\fR, since hash
+randomization is enabled by default.
+.TP
.B \-s
Don't add user site directory to sys.path.
.TP
.BI "\-X " option
Set implementation-specific option. The following options are available:
- -X faulthandler: enable faulthandler
-
- -X showrefcount: 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
+ \fB-X cpu_count=\fIN\fR: override the return value of \fIos.cpu_count()\fR;
+ \fB-X cpu_count=default\fR cancels overriding; also \fBPYTHON_CPU_COUNT\fI
- -X tracemalloc: 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
-
- -X importtime: 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'
-
- -X dev: enable CPython's "development mode", introducing additional runtime
- checks which are too expensive to be enabled by default. It will not be
- more verbose than the default if the code is correct: new warnings are
- only emitted when an issue is detected. Effect of the developer mode:
- * Add default warning filter, as -W default
- * Install debug hooks on memory allocators: see the PyMem_SetupDebugHooks()
- C function
- * Enable the faulthandler module to dump the Python traceback on a crash
+ \fB-X dev\fR: enable CPython's "development mode", introducing additional
+ runtime checks which are too expensive to be enabled by default. It
+ will not be more verbose than the default if the code is correct: new
+ warnings are only emitted when an issue is detected. Effect of the
+ developer mode:
+ * Add default warning filter, as \fB-W default\fR
+ * Install debug hooks on memory allocators: see the
+ PyMem_SetupDebugHooks() C function
+ * Enable the faulthandler module to dump the Python traceback on a
+ crash
* Enable asyncio debug mode
* Set the dev_mode attribute of sys.flags to True
* io.IOBase destructor logs close() exceptions
- -X utf8: enable 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). See PYTHONUTF8 for more details
-
- -X pycache_prefix=PATH: enable writing .pyc files to a parallel tree rooted at the
- given directory instead of to the code tree.
-
- -X warn_default_encoding: enable opt-in EncodingWarning for 'encoding=None'
+ \fB-X importtime\fR: 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
+ \fBpython3 -X importtime -c 'import asyncio'\fR
- -X no_debug_ranges: disable 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.
+ \fB-X faulthandler\fR: enable faulthandler
- -X frozen_modules=[on|off]: whether or not frozen modules should be used.
+ \fB-X frozen_modules=\fR[\fBon\fR|\fBoff\fR]: whether or not frozen modules
+ should be used.
The default is "on" (or "off" if you are running a local build).
- -X int_max_str_digits=number: limit the size of int<->str conversions.
+ \fB-X gil=\fR[\fB0\fR|\fB1\fR]: enable (1) or disable (0) the GIL; also
+ \fBPYTHON_GIL\fR
+ Only available in builds configured with \fB--disable-gil\fR.
+
+ \fB-X int_max_str_digits=\fInumber\fR: limit the size of int<->str conversions.
This helps avoid denial of service attacks when parsing untrusted data.
The default is sys.int_info.default_max_str_digits. 0 disables.
+ \fB-X no_debug_ranges\fR: disable 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.
+
+ \fB-X perf\fR: support the Linux "perf" profiler; also \fBPYTHONPERFSUPPORT=1\fR
+
+ \fB-X perf_jit\fR: support the Linux "perf" profiler with DWARF support;
+ also \fBPYTHON_PERF_JIT_SUPPORT=1\fR
+
+ \fB-X presite=\fIMOD\fR: import this module before site; also \fBPYTHON_PRESITE\fR
+ This only works on debug builds.
+
+ \fB-X pycache_prefix=\fIPATH\fR: enable writing .pyc files to a parallel
+ tree rooted at the given directory instead of to the code tree.
+
+ \fB-X showrefcount\fR: 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
+
+ \fB-X tracemalloc\fR: 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
+
+ \fB-X utf8\fR: enable UTF-8 mode for operating system interfaces,
+ overriding the default locale-aware mode. \fB-X utf8=0\fR explicitly
+ disables UTF-8 mode (even when it would otherwise activate
+ automatically). See \fBPYTHONUTF8\fR for more details
+
+ \fB-X warn_default_encoding\fR: enable opt-in EncodingWarning for 'encoding=None'
+
.TP
.B \-x
Skip the first line of the source. This is intended for a DOS
interpreter.
.RE
.SH ENVIRONMENT VARIABLES
-.IP PYTHONSAFEPATH
-If this is set to a non-empty string, don't automatically prepend a potentially
-unsafe path to \fBsys.path\fP such as the current directory, the script's
-directory or an empty string. See also the \fB\-P\fP option.
-.IP PYTHONHOME
-Change the location of the standard Python libraries. By default, the
-libraries are searched in ${prefix}/lib/python<version> and
-${exec_prefix}/lib/python<version>, where ${prefix} and ${exec_prefix}
-are installation-dependent directories, both defaulting to
-\fI/usr/local\fP. 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}.
-.IP PYTHONPATH
-Augments the default search path for module files.
-The format is the same as the shell's $PATH: one or more directory
-pathnames separated by colons.
-Non-existent directories are silently ignored.
-The default search path is installation dependent, but generally
-begins with ${prefix}/lib/python<version> (see PYTHONHOME above).
-The default search path is always appended to $PYTHONPATH.
-If a script argument is given, the directory containing the script is
-inserted in the path in front of $PYTHONPATH.
-The search path can be manipulated from within a Python program as the
-variable
-.IR sys.path .
-.IP PYTHONPLATLIBDIR
-Override sys.platlibdir.
-.IP 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 name space 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
-.I sys.ps1
-and
-.I sys.ps2
-in this file.
-.IP PYTHONOPTIMIZE
-If this is set to a non-empty string it is equivalent to specifying
-the \fB\-O\fP option. If set to an integer, it is equivalent to
-specifying \fB\-O\fP multiple times.
+.IP PYTHONASYNCIODEBUG
+If this environment variable is set to a non-empty string, enable the debug
+mode of the asyncio module.
+.IP PYTHON_BASIC_REPL
+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.
+.IP PYTHONBREAKPOINT
+If this environment variable is set to 0, it disables the default debugger. It
+can be set to the callable of your debugger of choice.
+.IP PYTHONCOERCELOCALE
+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.
+.IP PYTHON_COLORS
+If this variable is set to 1, the interpreter will colorize various kinds of
+output. Setting it to 0 deactivates this behavior.
+.IP PYTHON_CPU_COUNT
+If this variable is set to a positive integer, it overrides the return
+values of \fIos.cpu_count\fR and \fIos.process_cpu_count\fR.
+.IP
+See also the \fB\-X cpu_count\fR option.
.IP PYTHONDEBUG
If this is set to a non-empty string it is equivalent to specifying
the \fB\-d\fP option. If set to an integer, it is equivalent to
specifying \fB\-d\fP multiple times.
+.IP PYTHONEXECUTABLE
+If this environment variable is set,
+.IB sys.argv[0]
+will be set to its value instead of the value got through the C runtime. Only
+works on Mac OS X.
+.IP PYTHONFAULTHANDLER
+If this environment variable is set to a non-empty string,
+.IR faulthandler.enable()
+is called at startup: install a handler for SIGSEGV, SIGFPE, SIGABRT, SIGBUS
+and SIGILL signals to dump the Python traceback.
+.IP
+This is equivalent to the \fB-X faulthandler\fP option.
+.IP PYTHON_FROZEN_MODULES
+If this variable is set to \fBon\fR or \fBoff\fR, it determines whether or not
+frozen modules are ignored by the import machinery. A value of \fBon\fR means
+they get imported and \fBoff\fR means they are ignored. The default is \fBon\fR
+for non-debug builds (the normal case) and \fBoff\fR for debug builds.
+.IP
+See also the \fB\-X frozen_modules\fR option.
+.IP PYTHON_GIL
+If this variable is set to 1, the global interpreter lock (GIL) will be forced
+on. Setting it to 0 forces the GIL off. Only available in builds configured
+with \fB--disable-gil\fP.
+.IP PYTHON_HISTORY
+This environment variable can be used to set the location of a history file
+(on Unix, it is \fI~/.python_history\fP by default).
+.IP
+This is equivalent to the \fB-X gil\fR option.
+.IP PYTHONNODEBUGRANGES
+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.
.IP PYTHONDONTWRITEBYTECODE
If this is set to a non-empty string it is equivalent to specifying
the \fB\-B\fP option (don't try to write
.I .pyc
files).
-.IP PYTHONINSPECT
-If this is set to a non-empty string it is equivalent to specifying
-the \fB\-i\fP option.
-.IP PYTHONIOENCODING
-If this is set before running the interpreter, it overrides the encoding used
-for stdin/stdout/stderr, in the syntax
-.IB encodingname ":" errorhandler
-The
-.IB errorhandler
-part is optional and has the same meaning as in str.encode. For stderr, the
-.IB errorhandler
- part is ignored; the handler will always be \'backslashreplace\'.
-.IP PYTHONNOUSERSITE
-If this is set to a non-empty string it is equivalent to specifying the
-\fB\-s\fP option (Don't add the user site directory to sys.path).
-.IP PYTHONUNBUFFERED
-If this is set to a non-empty string it is equivalent to specifying
-the \fB\-u\fP option.
-.IP PYTHONVERBOSE
-If this is set to a non-empty string it is equivalent to specifying
-the \fB\-v\fP option. If set to an integer, it is equivalent to
-specifying \fB\-v\fP multiple times.
-.IP PYTHONWARNINGS
-If this is set to a comma-separated string it is equivalent to
-specifying the \fB\-W\fP option for each separate value.
+.IP PYTHONDEVMODE
+If this environment variable is set to a non-empty string, enable Python's
+"development mode", introducing additional runtime checks that are too
+expensive to be enabled by default.
+.IP
+This is equivalent to the \fB\-X dev\fR option.
.IP PYTHONHASHSEED
If this variable is set to "random", a random value is used to seed the hashes
of str and bytes objects.
The integer must be a decimal number in the range [0,4294967295]. Specifying
the value 0 will disable hash randomization.
+.IP PYTHONHOME
+Change the location of the standard Python libraries. By default, the
+libraries are searched in ${prefix}/lib/python<version> and
+${exec_prefix}/lib/python<version>, where ${prefix} and ${exec_prefix}
+are installation-dependent directories, both defaulting to
+\fI/usr/local\fP. 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}.
+.IP PYTHONINSPECT
+If this is set to a non-empty string it is equivalent to specifying
+the \fB\-i\fP option.
.IP PYTHONINTMAXSTRDIGITS
Limit the maximum digit characters in an int value
when converting from a string and when converting an int back to a str.
A value of 0 disables the limit. Conversions to or from bases 2, 4, 8,
16, and 32 are never limited.
+.IP
+This is equivalent to the \fB-X int_max_str_digits=\fINUMBER\fR option.
+.IP PYTHONIOENCODING
+If this is set before running the interpreter, it overrides the encoding used
+for stdin/stdout/stderr, in the syntax
+.IB encodingname ":" errorhandler
+The
+.IB errorhandler
+part is optional and has the same meaning as in str.encode. For stderr, the
+.IB errorhandler
+part is ignored; the handler will always be \'backslashreplace\'.
.IP PYTHONMALLOC
Set the Python memory allocators and/or install debug hooks. The available
memory allocators are
environment variable is used to force the
.BR malloc (3)
allocator of the C library, or if Python is configured without pymalloc support.
-.IP PYTHONASYNCIODEBUG
-If this environment variable is set to a non-empty string, enable the debug
-mode of the asyncio module.
+.IP PYTHONNOUSERSITE
+If this is set to a non-empty string it is equivalent to specifying the
+\fB\-s\fP option (Don't add the user site directory to sys.path).
+.IP PYTHONOPTIMIZE
+If this is set to a non-empty string it is equivalent to specifying
+the \fB\-O\fP option. If set to an integer, it is equivalent to
+specifying \fB\-O\fP multiple times.
+.IP PYTHONPATH
+Augments the default search path for module files.
+The format is the same as the shell's $PATH: one or more directory
+pathnames separated by colons.
+Non-existent directories are silently ignored.
+The default search path is installation dependent, but generally
+begins with ${prefix}/lib/python<version> (see PYTHONHOME above).
+The default search path is always appended to $PYTHONPATH.
+If a script argument is given, the directory containing the script is
+inserted in the path in front of $PYTHONPATH.
+The search path can be manipulated from within a Python program as the
+variable
+.IR sys.path .
+.IP PYTHON_PERF_JIT_SUPPORT
+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.
+Setting to 0 disables.
+.IP
+See also the \fB\-X perf_jit\fR option.
+.IP PYTHONPERFSUPPORT
+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.
+Setting to 0 disables.
+.IP
+See also the \fB\-X perf\fR option.
+.IP PYTHONPLATLIBDIR
+Override sys.platlibdir.
+.IP 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
+\fB\-X importtime\fP on the command line.
+.IP PYTHONPYCACHEPREFIX
+If this is set, Python will write \fB.pyc\fR files in a mirror directory tree
+at this path, instead of in \fB__pycache__\fR directories within the source
+tree.
+.IP
+This is equivalent to specifying the \fB\-X pycache_prefix=\fIPATH\fR option.
+.IP PYTHONSAFEPATH
+If this is set to a non-empty string, don't automatically prepend a potentially
+unsafe path to \fBsys.path\fP such as the current directory, the script's
+directory or an empty string. See also the \fB\-P\fP option.
+.IP 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 name space 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
+.I sys.ps1
+and
+.I sys.ps2
+in this file.
.IP PYTHONTRACEMALLOC
If this environment variable is set to a non-empty string, start tracing
Python memory allocations using the tracemalloc module.
traceback of a trace. For example,
.IB PYTHONTRACEMALLOC=1
stores only the most recent frame.
-.IP PYTHONFAULTHANDLER
-If this environment variable is set to a non-empty string,
-.IR faulthandler.enable()
-is called at startup: install a handler for SIGSEGV, SIGFPE, SIGABRT, SIGBUS
-and SIGILL signals to dump the Python traceback.
-.IP
-This is equivalent to the \fB-X faulthandler\fP option.
-.IP PYTHONEXECUTABLE
-If this environment variable is set,
-.IB sys.argv[0]
-will be set to its value instead of the value got through the C runtime. Only
-works on Mac OS X.
+.IP PYTHONUNBUFFERED
+If this is set to a non-empty string it is equivalent to specifying
+the \fB\-u\fP option.
.IP PYTHONUSERBASE
Defines the user base directory, which is used to compute the path of the user
.IR site-packages
directory and installation paths for
.IR "python \-m pip install \-\-user" .
-.IP 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
-\fB\-X importtime\fP on the command line.
-.IP PYTHONBREAKPOINT
-If this environment variable is set to 0, it disables the default debugger. It
-can be set to the callable of your debugger of choice.
-.IP PYTHON_COLORS
-If this variable is set to 1, the interpreter will colorize various kinds of
-output. Setting it to 0 deactivates this behavior.
-.IP PYTHON_HISTORY
-This environment variable can be used to set the location of a history file
-(on Unix, it is \fI~/.python_history\fP by default).
-.IP PYTHON_GIL
-If this variable is set to 1, the global interpreter lock (GIL) will be forced
-on. Setting it to 0 forces the GIL off. Only available in builds configured
-with \fB--disable-gil\fP.
+.IP PYTHONUTF8
+If set to 1, enable the Python "UTF-8 Mode". Setting to 0 disables.
+.IP PYTHONVERBOSE
+If this is set to a non-empty string it is equivalent to specifying
+the \fB\-v\fP option. If set to an integer, it is equivalent to
+specifying \fB\-v\fP multiple times.
+.IP PYTHONWARNDEFAULTENCODING
+If this environment variable is set to a non-empty string, issue a
+\fIEncodingWarning\fR when the locale-specific default encoding is used.
+.IP PYTHONWARNINGS
+If this is set to a comma-separated string it is equivalent to
+specifying the \fB\-W\fP option for each separate value.
.SS Debug-mode variables
Setting these variables only has an effect in a debug build of Python, that is,
if Python was configured with the
.IP PYTHONDUMPREFS
If this environment variable is set, Python will dump objects and reference
counts still alive after shutting down the interpreter.
+.IP PYTHONDUMPREFSFILE
+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.
+.IP PYTHON_PRESITE
+If this variable is set to a module, that module will be imported
+early in the interpreter lifecycle, before the \fIsite\fR module is
+executed, and before the \fI__main__\fR module is created.
+This only works on debug builds.
+.IP
+This is equivalent to the \fB-X presite=\fImodule\fR option.
.SH AUTHOR
The Python Software Foundation: https://www.python.org/psf/
.SH INTERNET RESOURCES
projects / thirdparty / Python / cpython.git / commitdiff
