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sys.exec_prefix
A string giving the site-specific directory prefix where the platform-dependent Python files are installed; by default, this is also '/usr/local'. This can be set at build time with the --exec-prefix argument to the configure script. Specifically, all configuration files (e.g. the pyconfig.h header file) are installed in the directory exec_prefix/lib/pythonX.Y/config, and shared library modules are installed in exec_prefix/lib/pythonX.Y/lib-dynload, where X.Y is the version number of Python, for example 3.2. Note If a virtual environment is in effect, this value will be changed in site.py to point to the virtual environment. The value for the Python installation will still be available, via base_exec_prefix. | python.library.sys#sys.exec_prefix |
sys.exit([arg])
Exit from Python. This is implemented by raising the SystemExit exception, so cleanup actions specified by finally clauses of try statements are honored, and it is possible to intercept the exit attempt at an outer level. The optional argument arg can be an integer giving the exit status (defaulting to zero), or another type of object. If it is an integer, zero is considered “successful termination” and any nonzero value is considered “abnormal termination” by shells and the like. Most systems require it to be in the range 0–127, and produce undefined results otherwise. Some systems have a convention for assigning specific meanings to specific exit codes, but these are generally underdeveloped; Unix programs generally use 2 for command line syntax errors and 1 for all other kind of errors. If another type of object is passed, None is equivalent to passing zero, and any other object is printed to stderr and results in an exit code of 1. In particular, sys.exit("some error message") is a quick way to exit a program when an error occurs. Since exit() ultimately “only” raises an exception, it will only exit the process when called from the main thread, and the exception is not intercepted. Changed in version 3.6: If an error occurs in the cleanup after the Python interpreter has caught SystemExit (such as an error flushing buffered data in the standard streams), the exit status is changed to 120. | python.library.sys#sys.exit |
sys.flags
The named tuple flags exposes the status of command line flags. The attributes are read only.
attribute flag
debug -d
inspect -i
interactive -i
isolated -I
optimize -O or -OO
dont_write_bytecode -B
no_user_site -s
no_site -S
ignore_environment -E
verbose -v
bytes_warning -b
quiet -q
hash_randomization -R
dev_mode -X dev (Python Development Mode)
utf8_mode -X utf8 Changed in version 3.2: Added quiet attribute for the new -q flag. New in version 3.2.3: The hash_randomization attribute. Changed in version 3.3: Removed obsolete division_warning attribute. Changed in version 3.4: Added isolated attribute for -I isolated flag. Changed in version 3.7: Added the dev_mode attribute for the new Python Development Mode and the utf8_mode attribute for the new -X utf8 flag. | python.library.sys#sys.flags |
sys.float_info
A named tuple holding information about the float type. It contains low level information about the precision and internal representation. The values correspond to the various floating-point constants defined in the standard header file float.h for the ‘C’ programming language; see section 5.2.4.2.2 of the 1999 ISO/IEC C standard [C99], ‘Characteristics of floating types’, for details.
attribute float.h macro explanation
epsilon DBL_EPSILON
difference between 1.0 and the least value greater than 1.0 that is representable as a float See also math.ulp().
dig DBL_DIG maximum number of decimal digits that can be faithfully represented in a float; see below
mant_dig DBL_MANT_DIG float precision: the number of base-radix digits in the significand of a float
max DBL_MAX maximum representable positive finite float
max_exp DBL_MAX_EXP maximum integer e such that radix**(e-1) is a representable finite float
max_10_exp DBL_MAX_10_EXP maximum integer e such that 10**e is in the range of representable finite floats
min DBL_MIN
minimum representable positive normalized float Use math.ulp(0.0) to get the smallest positive denormalized representable float.
min_exp DBL_MIN_EXP minimum integer e such that radix**(e-1) is a normalized float
min_10_exp DBL_MIN_10_EXP minimum integer e such that 10**e is a normalized float
radix FLT_RADIX radix of exponent representation
rounds FLT_ROUNDS integer constant representing the rounding mode used for arithmetic operations. This reflects the value of the system FLT_ROUNDS macro at interpreter startup time. See section 5.2.4.2.2 of the C99 standard for an explanation of the possible values and their meanings. The attribute sys.float_info.dig needs further explanation. If s is any string representing a decimal number with at most sys.float_info.dig significant digits, then converting s to a float and back again will recover a string representing the same decimal value: >>> import sys
>>> sys.float_info.dig
15
>>> s = '3.14159265358979' # decimal string with 15 significant digits
>>> format(float(s), '.15g') # convert to float and back -> same value
'3.14159265358979'
But for strings with more than sys.float_info.dig significant digits, this isn’t always true: >>> s = '9876543211234567' # 16 significant digits is too many!
>>> format(float(s), '.16g') # conversion changes value
'9876543211234568' | python.library.sys#sys.float_info |
sys.float_repr_style
A string indicating how the repr() function behaves for floats. If the string has value 'short' then for a finite float x, repr(x) aims to produce a short string with the property that float(repr(x)) == x. This is the usual behaviour in Python 3.1 and later. Otherwise, float_repr_style has value 'legacy' and repr(x) behaves in the same way as it did in versions of Python prior to 3.1. New in version 3.1. | python.library.sys#sys.float_repr_style |
sys.getallocatedblocks()
Return the number of memory blocks currently allocated by the interpreter, regardless of their size. This function is mainly useful for tracking and debugging memory leaks. Because of the interpreter’s internal caches, the result can vary from call to call; you may have to call _clear_type_cache() and gc.collect() to get more predictable results. If a Python build or implementation cannot reasonably compute this information, getallocatedblocks() is allowed to return 0 instead. New in version 3.4. | python.library.sys#sys.getallocatedblocks |
sys.getandroidapilevel()
Return the build time API version of Android as an integer. Availability: Android. New in version 3.7. | python.library.sys#sys.getandroidapilevel |
sys.getdefaultencoding()
Return the name of the current default string encoding used by the Unicode implementation. | python.library.sys#sys.getdefaultencoding |
sys.getdlopenflags()
Return the current value of the flags that are used for dlopen() calls. Symbolic names for the flag values can be found in the os module (RTLD_xxx constants, e.g. os.RTLD_LAZY). Availability: Unix. | python.library.sys#sys.getdlopenflags |
sys.getfilesystemencodeerrors()
Return the name of the error mode used to convert between Unicode filenames and bytes filenames. The encoding name is returned from getfilesystemencoding(). os.fsencode() and os.fsdecode() should be used to ensure that the correct encoding and errors mode are used. New in version 3.6. | python.library.sys#sys.getfilesystemencodeerrors |
sys.getfilesystemencoding()
Return the name of the encoding used to convert between Unicode filenames and bytes filenames. For best compatibility, str should be used for filenames in all cases, although representing filenames as bytes is also supported. Functions accepting or returning filenames should support either str or bytes and internally convert to the system’s preferred representation. This encoding is always ASCII-compatible. os.fsencode() and os.fsdecode() should be used to ensure that the correct encoding and errors mode are used. In the UTF-8 mode, the encoding is utf-8 on any platform. On macOS, the encoding is 'utf-8'. On Unix, the encoding is the locale encoding. On Windows, the encoding may be 'utf-8' or 'mbcs', depending on user configuration. On Android, the encoding is 'utf-8'. On VxWorks, the encoding is 'utf-8'. Changed in version 3.2: getfilesystemencoding() result cannot be None anymore. Changed in version 3.6: Windows is no longer guaranteed to return 'mbcs'. See PEP 529 and _enablelegacywindowsfsencoding() for more information. Changed in version 3.7: Return ‘utf-8’ in the UTF-8 mode. | python.library.sys#sys.getfilesystemencoding |
sys.getprofile()
Get the profiler function as set by setprofile(). | python.library.sys#sys.getprofile |
sys.getrecursionlimit()
Return the current value of the recursion limit, the maximum depth of the Python interpreter stack. This limit prevents infinite recursion from causing an overflow of the C stack and crashing Python. It can be set by setrecursionlimit(). | python.library.sys#sys.getrecursionlimit |
sys.getrefcount(object)
Return the reference count of the object. The count returned is generally one higher than you might expect, because it includes the (temporary) reference as an argument to getrefcount(). | python.library.sys#sys.getrefcount |
sys.getsizeof(object[, default])
Return the size of an object in bytes. The object can be any type of object. All built-in objects will return correct results, but this does not have to hold true for third-party extensions as it is implementation specific. Only the memory consumption directly attributed to the object is accounted for, not the memory consumption of objects it refers to. If given, default will be returned if the object does not provide means to retrieve the size. Otherwise a TypeError will be raised. getsizeof() calls the object’s __sizeof__ method and adds an additional garbage collector overhead if the object is managed by the garbage collector. See recursive sizeof recipe for an example of using getsizeof() recursively to find the size of containers and all their contents. | python.library.sys#sys.getsizeof |
sys.getswitchinterval()
Return the interpreter’s “thread switch interval”; see setswitchinterval(). New in version 3.2. | python.library.sys#sys.getswitchinterval |
sys.gettrace()
Get the trace function as set by settrace(). CPython implementation detail: The gettrace() function is intended only for implementing debuggers, profilers, coverage tools and the like. Its behavior is part of the implementation platform, rather than part of the language definition, and thus may not be available in all Python implementations. | python.library.sys#sys.gettrace |
sys.getwindowsversion()
Return a named tuple describing the Windows version currently running. The named elements are major, minor, build, platform, service_pack, service_pack_minor, service_pack_major, suite_mask, product_type and platform_version. service_pack contains a string, platform_version a 3-tuple and all other values are integers. The components can also be accessed by name, so sys.getwindowsversion()[0] is equivalent to sys.getwindowsversion().major. For compatibility with prior versions, only the first 5 elements are retrievable by indexing. platform will be 2 (VER_PLATFORM_WIN32_NT). product_type may be one of the following values:
Constant Meaning
1 (VER_NT_WORKSTATION) The system is a workstation.
2 (VER_NT_DOMAIN_CONTROLLER) The system is a domain controller.
3 (VER_NT_SERVER) The system is a server, but not a domain controller. This function wraps the Win32 GetVersionEx() function; see the Microsoft documentation on OSVERSIONINFOEX() for more information about these fields. platform_version returns the major version, minor version and build number of the current operating system, rather than the version that is being emulated for the process. It is intended for use in logging rather than for feature detection. Note platform_version derives the version from kernel32.dll which can be of a different version than the OS version. Please use platform module for achieving accurate OS version. Availability: Windows. Changed in version 3.2: Changed to a named tuple and added service_pack_minor, service_pack_major, suite_mask, and product_type. Changed in version 3.6: Added platform_version | python.library.sys#sys.getwindowsversion |
sys.get_asyncgen_hooks()
Returns an asyncgen_hooks object, which is similar to a namedtuple of the form (firstiter, finalizer), where firstiter and finalizer are expected to be either None or functions which take an asynchronous generator iterator as an argument, and are used to schedule finalization of an asynchronous generator by an event loop. New in version 3.6: See PEP 525 for more details. Note This function has been added on a provisional basis (see PEP 411 for details.) | python.library.sys#sys.get_asyncgen_hooks |
sys.get_coroutine_origin_tracking_depth()
Get the current coroutine origin tracking depth, as set by set_coroutine_origin_tracking_depth(). New in version 3.7. Note This function has been added on a provisional basis (see PEP 411 for details.) Use it only for debugging purposes. | python.library.sys#sys.get_coroutine_origin_tracking_depth |
sys.hash_info
A named tuple giving parameters of the numeric hash implementation. For more details about hashing of numeric types, see Hashing of numeric types.
attribute explanation
width width in bits used for hash values
modulus prime modulus P used for numeric hash scheme
inf hash value returned for a positive infinity
nan hash value returned for a nan
imag multiplier used for the imaginary part of a complex number
algorithm name of the algorithm for hashing of str, bytes, and memoryview
hash_bits internal output size of the hash algorithm
seed_bits size of the seed key of the hash algorithm New in version 3.2. Changed in version 3.4: Added algorithm, hash_bits and seed_bits | python.library.sys#sys.hash_info |
sys.hexversion
The version number encoded as a single integer. This is guaranteed to increase with each version, including proper support for non-production releases. For example, to test that the Python interpreter is at least version 1.5.2, use: if sys.hexversion >= 0x010502F0:
# use some advanced feature
...
else:
# use an alternative implementation or warn the user
...
This is called hexversion since it only really looks meaningful when viewed as the result of passing it to the built-in hex() function. The named tuple sys.version_info may be used for a more human-friendly encoding of the same information. More details of hexversion can be found at API and ABI Versioning. | python.library.sys#sys.hexversion |
sys.implementation
An object containing information about the implementation of the currently running Python interpreter. The following attributes are required to exist in all Python implementations. name is the implementation’s identifier, e.g. 'cpython'. The actual string is defined by the Python implementation, but it is guaranteed to be lower case. version is a named tuple, in the same format as sys.version_info. It represents the version of the Python implementation. This has a distinct meaning from the specific version of the Python language to which the currently running interpreter conforms, which sys.version_info represents. For example, for PyPy 1.8 sys.implementation.version might be sys.version_info(1, 8, 0, 'final', 0), whereas sys.version_info would be sys.version_info(2, 7, 2, 'final', 0). For CPython they are the same value, since it is the reference implementation. hexversion is the implementation version in hexadecimal format, like sys.hexversion. cache_tag is the tag used by the import machinery in the filenames of cached modules. By convention, it would be a composite of the implementation’s name and version, like 'cpython-33'. However, a Python implementation may use some other value if appropriate. If cache_tag is set to None, it indicates that module caching should be disabled. sys.implementation may contain additional attributes specific to the Python implementation. These non-standard attributes must start with an underscore, and are not described here. Regardless of its contents, sys.implementation will not change during a run of the interpreter, nor between implementation versions. (It may change between Python language versions, however.) See PEP 421 for more information. New in version 3.3. Note The addition of new required attributes must go through the normal PEP process. See PEP 421 for more information. | python.library.sys#sys.implementation |
sys.intern(string)
Enter string in the table of “interned” strings and return the interned string – which is string itself or a copy. Interning strings is useful to gain a little performance on dictionary lookup – if the keys in a dictionary are interned, and the lookup key is interned, the key comparisons (after hashing) can be done by a pointer compare instead of a string compare. Normally, the names used in Python programs are automatically interned, and the dictionaries used to hold module, class or instance attributes have interned keys. Interned strings are not immortal; you must keep a reference to the return value of intern() around to benefit from it. | python.library.sys#sys.intern |
sys.int_info
A named tuple that holds information about Python’s internal representation of integers. The attributes are read only.
Attribute Explanation
bits_per_digit number of bits held in each digit. Python integers are stored internally in base 2**int_info.bits_per_digit
sizeof_digit size in bytes of the C type used to represent a digit New in version 3.1. | python.library.sys#sys.int_info |
sys.is_finalizing()
Return True if the Python interpreter is shutting down, False otherwise. New in version 3.5. | python.library.sys#sys.is_finalizing |
sys.last_type
sys.last_value
sys.last_traceback
These three variables are not always defined; they are set when an exception is not handled and the interpreter prints an error message and a stack traceback. Their intended use is to allow an interactive user to import a debugger module and engage in post-mortem debugging without having to re-execute the command that caused the error. (Typical use is import pdb; pdb.pm() to enter the post-mortem debugger; see pdb module for more information.) The meaning of the variables is the same as that of the return values from exc_info() above. | python.library.sys#sys.last_traceback |
sys.last_type
sys.last_value
sys.last_traceback
These three variables are not always defined; they are set when an exception is not handled and the interpreter prints an error message and a stack traceback. Their intended use is to allow an interactive user to import a debugger module and engage in post-mortem debugging without having to re-execute the command that caused the error. (Typical use is import pdb; pdb.pm() to enter the post-mortem debugger; see pdb module for more information.) The meaning of the variables is the same as that of the return values from exc_info() above. | python.library.sys#sys.last_type |
sys.last_type
sys.last_value
sys.last_traceback
These three variables are not always defined; they are set when an exception is not handled and the interpreter prints an error message and a stack traceback. Their intended use is to allow an interactive user to import a debugger module and engage in post-mortem debugging without having to re-execute the command that caused the error. (Typical use is import pdb; pdb.pm() to enter the post-mortem debugger; see pdb module for more information.) The meaning of the variables is the same as that of the return values from exc_info() above. | python.library.sys#sys.last_value |
sys.maxsize
An integer giving the maximum value a variable of type Py_ssize_t can take. It’s usually 2**31 - 1 on a 32-bit platform and 2**63 - 1 on a 64-bit platform. | python.library.sys#sys.maxsize |
sys.maxunicode
An integer giving the value of the largest Unicode code point, i.e. 1114111 (0x10FFFF in hexadecimal). Changed in version 3.3: Before PEP 393, sys.maxunicode used to be either 0xFFFF or 0x10FFFF, depending on the configuration option that specified whether Unicode characters were stored as UCS-2 or UCS-4. | python.library.sys#sys.maxunicode |
sys.meta_path
A list of meta path finder objects that have their find_spec() methods called to see if one of the objects can find the module to be imported. The find_spec() method is called with at least the absolute name of the module being imported. If the module to be imported is contained in a package, then the parent package’s __path__ attribute is passed in as a second argument. The method returns a module spec, or None if the module cannot be found. See also
importlib.abc.MetaPathFinder
The abstract base class defining the interface of finder objects on meta_path.
importlib.machinery.ModuleSpec
The concrete class which find_spec() should return instances of. Changed in version 3.4: Module specs were introduced in Python 3.4, by PEP 451. Earlier versions of Python looked for a method called find_module(). This is still called as a fallback if a meta_path entry doesn’t have a find_spec() method. | python.library.sys#sys.meta_path |
sys.modules
This is a dictionary that maps module names to modules which have already been loaded. This can be manipulated to force reloading of modules and other tricks. However, replacing the dictionary will not necessarily work as expected and deleting essential items from the dictionary may cause Python to fail. | python.library.sys#sys.modules |
sys.path
A list of strings that specifies the search path for modules. Initialized from the environment variable PYTHONPATH, plus an installation-dependent default. As initialized upon program startup, the first item of this list, path[0], is the directory containing the script that was used to invoke the Python interpreter. If the script directory is not available (e.g. if the interpreter is invoked interactively or if the script is read from standard input), path[0] is the empty string, which directs Python to search modules in the current directory first. Notice that the script directory is inserted before the entries inserted as a result of PYTHONPATH. A program is free to modify this list for its own purposes. Only strings and bytes should be added to sys.path; all other data types are ignored during import. See also Module site This describes how to use .pth files to extend sys.path. | python.library.sys#sys.path |
sys.path_hooks
A list of callables that take a path argument to try to create a finder for the path. If a finder can be created, it is to be returned by the callable, else raise ImportError. Originally specified in PEP 302. | python.library.sys#sys.path_hooks |
sys.path_importer_cache
A dictionary acting as a cache for finder objects. The keys are paths that have been passed to sys.path_hooks and the values are the finders that are found. If a path is a valid file system path but no finder is found on sys.path_hooks then None is stored. Originally specified in PEP 302. Changed in version 3.3: None is stored instead of imp.NullImporter when no finder is found. | python.library.sys#sys.path_importer_cache |
sys.platform
This string contains a platform identifier that can be used to append platform-specific components to sys.path, for instance. For Unix systems, except on Linux and AIX, this is the lowercased OS name as returned by uname -s with the first part of the version as returned by uname -r appended, e.g. 'sunos5' or 'freebsd8', at the time when Python was built. Unless you want to test for a specific system version, it is therefore recommended to use the following idiom: if sys.platform.startswith('freebsd'):
# FreeBSD-specific code here...
elif sys.platform.startswith('linux'):
# Linux-specific code here...
elif sys.platform.startswith('aix'):
# AIX-specific code here...
For other systems, the values are:
System platform value
AIX 'aix'
Linux 'linux'
Windows 'win32'
Windows/Cygwin 'cygwin'
macOS 'darwin' Changed in version 3.3: On Linux, sys.platform doesn’t contain the major version anymore. It is always 'linux', instead of 'linux2' or 'linux3'. Since older Python versions include the version number, it is recommended to always use the startswith idiom presented above. Changed in version 3.8: On AIX, sys.platform doesn’t contain the major version anymore. It is always 'aix', instead of 'aix5' or 'aix7'. Since older Python versions include the version number, it is recommended to always use the startswith idiom presented above. See also os.name has a coarser granularity. os.uname() gives system-dependent version information. The platform module provides detailed checks for the system’s identity. | python.library.sys#sys.platform |
sys.platlibdir
Name of the platform-specific library directory. It is used to build the path of standard library and the paths of installed extension modules. It is equal to "lib" on most platforms. On Fedora and SuSE, it is equal to "lib64" on 64-bit platforms which gives the following sys.path paths (where X.Y is the Python major.minor version):
/usr/lib64/pythonX.Y/: Standard library (like os.py of the os module)
/usr/lib64/pythonX.Y/lib-dynload/: C extension modules of the standard library (like the errno module, the exact filename is platform specific)
/usr/lib/pythonX.Y/site-packages/ (always use lib, not sys.platlibdir): Third-party modules
/usr/lib64/pythonX.Y/site-packages/: C extension modules of third-party packages New in version 3.9. | python.library.sys#sys.platlibdir |
sys.prefix
A string giving the site-specific directory prefix where the platform independent Python files are installed; by default, this is the string '/usr/local'. This can be set at build time with the --prefix argument to the configure script. The main collection of Python library modules is installed in the directory prefix/lib/pythonX.Y while the platform independent header files (all except pyconfig.h) are stored in prefix/include/pythonX.Y, where X.Y is the version number of Python, for example 3.2. Note If a virtual environment is in effect, this value will be changed in site.py to point to the virtual environment. The value for the Python installation will still be available, via base_prefix. | python.library.sys#sys.prefix |
sys.ps1
sys.ps2
Strings specifying the primary and secondary prompt of the interpreter. These are only defined if the interpreter is in interactive mode. Their initial values in this case are '>>> ' and '... '. If a non-string object is assigned to either variable, its str() is re-evaluated each time the interpreter prepares to read a new interactive command; this can be used to implement a dynamic prompt. | python.library.sys#sys.ps1 |
sys.ps1
sys.ps2
Strings specifying the primary and secondary prompt of the interpreter. These are only defined if the interpreter is in interactive mode. Their initial values in this case are '>>> ' and '... '. If a non-string object is assigned to either variable, its str() is re-evaluated each time the interpreter prepares to read a new interactive command; this can be used to implement a dynamic prompt. | python.library.sys#sys.ps2 |
sys.pycache_prefix
If this is set (not None), Python will write bytecode-cache .pyc files to (and read them from) a parallel directory tree rooted at this directory, rather than from __pycache__ directories in the source code tree. Any __pycache__ directories in the source code tree will be ignored and new .pyc files written within the pycache prefix. Thus if you use compileall as a pre-build step, you must ensure you run it with the same pycache prefix (if any) that you will use at runtime. A relative path is interpreted relative to the current working directory. This value is initially set based on the value of the -X pycache_prefix=PATH command-line option or the PYTHONPYCACHEPREFIX environment variable (command-line takes precedence). If neither are set, it is None. New in version 3.8. | python.library.sys#sys.pycache_prefix |
sys.setdlopenflags(n)
Set the flags used by the interpreter for dlopen() calls, such as when the interpreter loads extension modules. Among other things, this will enable a lazy resolving of symbols when importing a module, if called as sys.setdlopenflags(0). To share symbols across extension modules, call as sys.setdlopenflags(os.RTLD_GLOBAL). Symbolic names for the flag values can be found in the os module (RTLD_xxx constants, e.g. os.RTLD_LAZY). Availability: Unix. | python.library.sys#sys.setdlopenflags |
sys.setprofile(profilefunc)
Set the system’s profile function, which allows you to implement a Python source code profiler in Python. See chapter The Python Profilers for more information on the Python profiler. The system’s profile function is called similarly to the system’s trace function (see settrace()), but it is called with different events, for example it isn’t called for each executed line of code (only on call and return, but the return event is reported even when an exception has been set). The function is thread-specific, but there is no way for the profiler to know about context switches between threads, so it does not make sense to use this in the presence of multiple threads. Also, its return value is not used, so it can simply return None. Error in the profile function will cause itself unset. Profile functions should have three arguments: frame, event, and arg. frame is the current stack frame. event is a string: 'call', 'return', 'c_call', 'c_return', or 'c_exception'. arg depends on the event type. Raises an auditing event sys.setprofile with no arguments. The events have the following meaning:
'call'
A function is called (or some other code block entered). The profile function is called; arg is None.
'return'
A function (or other code block) is about to return. The profile function is called; arg is the value that will be returned, or None if the event is caused by an exception being raised.
'c_call'
A C function is about to be called. This may be an extension function or a built-in. arg is the C function object.
'c_return'
A C function has returned. arg is the C function object.
'c_exception'
A C function has raised an exception. arg is the C function object. | python.library.sys#sys.setprofile |
sys.setrecursionlimit(limit)
Set the maximum depth of the Python interpreter stack to limit. This limit prevents infinite recursion from causing an overflow of the C stack and crashing Python. The highest possible limit is platform-dependent. A user may need to set the limit higher when they have a program that requires deep recursion and a platform that supports a higher limit. This should be done with care, because a too-high limit can lead to a crash. If the new limit is too low at the current recursion depth, a RecursionError exception is raised. Changed in version 3.5.1: A RecursionError exception is now raised if the new limit is too low at the current recursion depth. | python.library.sys#sys.setrecursionlimit |
sys.setswitchinterval(interval)
Set the interpreter’s thread switch interval (in seconds). This floating-point value determines the ideal duration of the “timeslices” allocated to concurrently running Python threads. Please note that the actual value can be higher, especially if long-running internal functions or methods are used. Also, which thread becomes scheduled at the end of the interval is the operating system’s decision. The interpreter doesn’t have its own scheduler. New in version 3.2. | python.library.sys#sys.setswitchinterval |
sys.settrace(tracefunc)
Set the system’s trace function, which allows you to implement a Python source code debugger in Python. The function is thread-specific; for a debugger to support multiple threads, it must register a trace function using settrace() for each thread being debugged or use threading.settrace(). Trace functions should have three arguments: frame, event, and arg. frame is the current stack frame. event is a string: 'call', 'line', 'return', 'exception' or 'opcode'. arg depends on the event type. The trace function is invoked (with event set to 'call') whenever a new local scope is entered; it should return a reference to a local trace function to be used for the new scope, or None if the scope shouldn’t be traced. The local trace function should return a reference to itself (or to another function for further tracing in that scope), or None to turn off tracing in that scope. If there is any error occurred in the trace function, it will be unset, just like settrace(None) is called. The events have the following meaning:
'call'
A function is called (or some other code block entered). The global trace function is called; arg is None; the return value specifies the local trace function.
'line'
The interpreter is about to execute a new line of code or re-execute the condition of a loop. The local trace function is called; arg is None; the return value specifies the new local trace function. See Objects/lnotab_notes.txt for a detailed explanation of how this works. Per-line events may be disabled for a frame by setting f_trace_lines to False on that frame.
'return'
A function (or other code block) is about to return. The local trace function is called; arg is the value that will be returned, or None if the event is caused by an exception being raised. The trace function’s return value is ignored.
'exception'
An exception has occurred. The local trace function is called; arg is a tuple (exception, value, traceback); the return value specifies the new local trace function.
'opcode'
The interpreter is about to execute a new opcode (see dis for opcode details). The local trace function is called; arg is None; the return value specifies the new local trace function. Per-opcode events are not emitted by default: they must be explicitly requested by setting f_trace_opcodes to True on the frame. Note that as an exception is propagated down the chain of callers, an 'exception' event is generated at each level. For more fine-grained usage, it’s possible to set a trace function by assigning frame.f_trace = tracefunc explicitly, rather than relying on it being set indirectly via the return value from an already installed trace function. This is also required for activating the trace function on the current frame, which settrace() doesn’t do. Note that in order for this to work, a global tracing function must have been installed with settrace() in order to enable the runtime tracing machinery, but it doesn’t need to be the same tracing function (e.g. it could be a low overhead tracing function that simply returns None to disable itself immediately on each frame). For more information on code and frame objects, refer to The standard type hierarchy. Raises an auditing event sys.settrace with no arguments. CPython implementation detail: The settrace() function is intended only for implementing debuggers, profilers, coverage tools and the like. Its behavior is part of the implementation platform, rather than part of the language definition, and thus may not be available in all Python implementations. Changed in version 3.7: 'opcode' event type added; f_trace_lines and f_trace_opcodes attributes added to frames | python.library.sys#sys.settrace |
sys.set_asyncgen_hooks(firstiter, finalizer)
Accepts two optional keyword arguments which are callables that accept an asynchronous generator iterator as an argument. The firstiter callable will be called when an asynchronous generator is iterated for the first time. The finalizer will be called when an asynchronous generator is about to be garbage collected. Raises an auditing event sys.set_asyncgen_hooks_firstiter with no arguments. Raises an auditing event sys.set_asyncgen_hooks_finalizer with no arguments. Two auditing events are raised because the underlying API consists of two calls, each of which must raise its own event. New in version 3.6: See PEP 525 for more details, and for a reference example of a finalizer method see the implementation of asyncio.Loop.shutdown_asyncgens in Lib/asyncio/base_events.py Note This function has been added on a provisional basis (see PEP 411 for details.) | python.library.sys#sys.set_asyncgen_hooks |
sys.set_coroutine_origin_tracking_depth(depth)
Allows enabling or disabling coroutine origin tracking. When enabled, the cr_origin attribute on coroutine objects will contain a tuple of (filename, line number, function name) tuples describing the traceback where the coroutine object was created, with the most recent call first. When disabled, cr_origin will be None. To enable, pass a depth value greater than zero; this sets the number of frames whose information will be captured. To disable, pass set depth to zero. This setting is thread-specific. New in version 3.7. Note This function has been added on a provisional basis (see PEP 411 for details.) Use it only for debugging purposes. | python.library.sys#sys.set_coroutine_origin_tracking_depth |
sys.stdin
sys.stdout
sys.stderr
File objects used by the interpreter for standard input, output and errors:
stdin is used for all interactive input (including calls to input());
stdout is used for the output of print() and expression statements and for the prompts of input(); The interpreter’s own prompts and its error messages go to stderr. These streams are regular text files like those returned by the open() function. Their parameters are chosen as follows:
The character encoding is platform-dependent. Non-Windows platforms use the locale encoding (see locale.getpreferredencoding()). On Windows, UTF-8 is used for the console device. Non-character devices such as disk files and pipes use the system locale encoding (i.e. the ANSI codepage). Non-console character devices such as NUL (i.e. where isatty() returns True) use the value of the console input and output codepages at startup, respectively for stdin and stdout/stderr. This defaults to the system locale encoding if the process is not initially attached to a console. The special behaviour of the console can be overridden by setting the environment variable PYTHONLEGACYWINDOWSSTDIO before starting Python. In that case, the console codepages are used as for any other character device. Under all platforms, you can override the character encoding by setting the PYTHONIOENCODING environment variable before starting Python or by using the new -X utf8 command line option and PYTHONUTF8 environment variable. However, for the Windows console, this only applies when PYTHONLEGACYWINDOWSSTDIO is also set. When interactive, the stdout stream is line-buffered. Otherwise, it is block-buffered like regular text files. The stderr stream is line-buffered in both cases. You can make both streams unbuffered by passing the -u command-line option or setting the PYTHONUNBUFFERED environment variable. Changed in version 3.9: Non-interactive stderr is now line-buffered instead of fully buffered. Note To write or read binary data from/to the standard streams, use the underlying binary buffer object. For example, to write bytes to stdout, use sys.stdout.buffer.write(b'abc'). However, if you are writing a library (and do not control in which context its code will be executed), be aware that the standard streams may be replaced with file-like objects like io.StringIO which do not support the buffer attribute. | python.library.sys#sys.stderr |
sys.stdin
sys.stdout
sys.stderr
File objects used by the interpreter for standard input, output and errors:
stdin is used for all interactive input (including calls to input());
stdout is used for the output of print() and expression statements and for the prompts of input(); The interpreter’s own prompts and its error messages go to stderr. These streams are regular text files like those returned by the open() function. Their parameters are chosen as follows:
The character encoding is platform-dependent. Non-Windows platforms use the locale encoding (see locale.getpreferredencoding()). On Windows, UTF-8 is used for the console device. Non-character devices such as disk files and pipes use the system locale encoding (i.e. the ANSI codepage). Non-console character devices such as NUL (i.e. where isatty() returns True) use the value of the console input and output codepages at startup, respectively for stdin and stdout/stderr. This defaults to the system locale encoding if the process is not initially attached to a console. The special behaviour of the console can be overridden by setting the environment variable PYTHONLEGACYWINDOWSSTDIO before starting Python. In that case, the console codepages are used as for any other character device. Under all platforms, you can override the character encoding by setting the PYTHONIOENCODING environment variable before starting Python or by using the new -X utf8 command line option and PYTHONUTF8 environment variable. However, for the Windows console, this only applies when PYTHONLEGACYWINDOWSSTDIO is also set. When interactive, the stdout stream is line-buffered. Otherwise, it is block-buffered like regular text files. The stderr stream is line-buffered in both cases. You can make both streams unbuffered by passing the -u command-line option or setting the PYTHONUNBUFFERED environment variable. Changed in version 3.9: Non-interactive stderr is now line-buffered instead of fully buffered. Note To write or read binary data from/to the standard streams, use the underlying binary buffer object. For example, to write bytes to stdout, use sys.stdout.buffer.write(b'abc'). However, if you are writing a library (and do not control in which context its code will be executed), be aware that the standard streams may be replaced with file-like objects like io.StringIO which do not support the buffer attribute. | python.library.sys#sys.stdin |
sys.stdin
sys.stdout
sys.stderr
File objects used by the interpreter for standard input, output and errors:
stdin is used for all interactive input (including calls to input());
stdout is used for the output of print() and expression statements and for the prompts of input(); The interpreter’s own prompts and its error messages go to stderr. These streams are regular text files like those returned by the open() function. Their parameters are chosen as follows:
The character encoding is platform-dependent. Non-Windows platforms use the locale encoding (see locale.getpreferredencoding()). On Windows, UTF-8 is used for the console device. Non-character devices such as disk files and pipes use the system locale encoding (i.e. the ANSI codepage). Non-console character devices such as NUL (i.e. where isatty() returns True) use the value of the console input and output codepages at startup, respectively for stdin and stdout/stderr. This defaults to the system locale encoding if the process is not initially attached to a console. The special behaviour of the console can be overridden by setting the environment variable PYTHONLEGACYWINDOWSSTDIO before starting Python. In that case, the console codepages are used as for any other character device. Under all platforms, you can override the character encoding by setting the PYTHONIOENCODING environment variable before starting Python or by using the new -X utf8 command line option and PYTHONUTF8 environment variable. However, for the Windows console, this only applies when PYTHONLEGACYWINDOWSSTDIO is also set. When interactive, the stdout stream is line-buffered. Otherwise, it is block-buffered like regular text files. The stderr stream is line-buffered in both cases. You can make both streams unbuffered by passing the -u command-line option or setting the PYTHONUNBUFFERED environment variable. Changed in version 3.9: Non-interactive stderr is now line-buffered instead of fully buffered. Note To write or read binary data from/to the standard streams, use the underlying binary buffer object. For example, to write bytes to stdout, use sys.stdout.buffer.write(b'abc'). However, if you are writing a library (and do not control in which context its code will be executed), be aware that the standard streams may be replaced with file-like objects like io.StringIO which do not support the buffer attribute. | python.library.sys#sys.stdout |
sys.thread_info
A named tuple holding information about the thread implementation.
Attribute Explanation
name
Name of the thread implementation:
'nt': Windows threads
'pthread': POSIX threads
'solaris': Solaris threads
lock
Name of the lock implementation:
'semaphore': a lock uses a semaphore
'mutex+cond': a lock uses a mutex and a condition variable
None if this information is unknown
version Name and version of the thread library. It is a string, or None if this information is unknown. New in version 3.3. | python.library.sys#sys.thread_info |
sys.tracebacklimit
When this variable is set to an integer value, it determines the maximum number of levels of traceback information printed when an unhandled exception occurs. The default is 1000. When set to 0 or less, all traceback information is suppressed and only the exception type and value are printed. | python.library.sys#sys.tracebacklimit |
sys.unraisablehook(unraisable, /)
Handle an unraisable exception. Called when an exception has occurred but there is no way for Python to handle it. For example, when a destructor raises an exception or during garbage collection (gc.collect()). The unraisable argument has the following attributes:
exc_type: Exception type.
exc_value: Exception value, can be None.
exc_traceback: Exception traceback, can be None.
err_msg: Error message, can be None.
object: Object causing the exception, can be None. The default hook formats err_msg and object as: f'{err_msg}: {object!r}'; use “Exception ignored in” error message if err_msg is None. sys.unraisablehook() can be overridden to control how unraisable exceptions are handled. Storing exc_value using a custom hook can create a reference cycle. It should be cleared explicitly to break the reference cycle when the exception is no longer needed. Storing object using a custom hook can resurrect it if it is set to an object which is being finalized. Avoid storing object after the custom hook completes to avoid resurrecting objects. See also excepthook() which handles uncaught exceptions.
Raise an auditing event sys.unraisablehook with arguments hook, unraisable when an exception that cannot be handled occurs. The unraisable object is the same as what will be passed to the hook. If no hook has been set, hook may be None. New in version 3.8. | python.library.sys#sys.unraisablehook |
sys.version
A string containing the version number of the Python interpreter plus additional information on the build number and compiler used. This string is displayed when the interactive interpreter is started. Do not extract version information out of it, rather, use version_info and the functions provided by the platform module. | python.library.sys#sys.version |
sys.version_info
A tuple containing the five components of the version number: major, minor, micro, releaselevel, and serial. All values except releaselevel are integers; the release level is 'alpha', 'beta', 'candidate', or 'final'. The version_info value corresponding to the Python version 2.0 is (2, 0, 0, 'final', 0). The components can also be accessed by name, so sys.version_info[0] is equivalent to sys.version_info.major and so on. Changed in version 3.1: Added named component attributes. | python.library.sys#sys.version_info |
sys.warnoptions
This is an implementation detail of the warnings framework; do not modify this value. Refer to the warnings module for more information on the warnings framework. | python.library.sys#sys.warnoptions |
sys.winver
The version number used to form registry keys on Windows platforms. This is stored as string resource 1000 in the Python DLL. The value is normally the first three characters of version. It is provided in the sys module for informational purposes; modifying this value has no effect on the registry keys used by Python. Availability: Windows. | python.library.sys#sys.winver |
sys._clear_type_cache()
Clear the internal type cache. The type cache is used to speed up attribute and method lookups. Use the function only to drop unnecessary references during reference leak debugging. This function should be used for internal and specialized purposes only. | python.library.sys#sys._clear_type_cache |
sys._current_frames()
Return a dictionary mapping each thread’s identifier to the topmost stack frame currently active in that thread at the time the function is called. Note that functions in the traceback module can build the call stack given such a frame. This is most useful for debugging deadlock: this function does not require the deadlocked threads’ cooperation, and such threads’ call stacks are frozen for as long as they remain deadlocked. The frame returned for a non-deadlocked thread may bear no relationship to that thread’s current activity by the time calling code examines the frame. This function should be used for internal and specialized purposes only. Raises an auditing event sys._current_frames with no arguments. | python.library.sys#sys._current_frames |
sys._debugmallocstats()
Print low-level information to stderr about the state of CPython’s memory allocator. If Python is configured –with-pydebug, it also performs some expensive internal consistency checks. New in version 3.3. CPython implementation detail: This function is specific to CPython. The exact output format is not defined here, and may change. | python.library.sys#sys._debugmallocstats |
sys._enablelegacywindowsfsencoding()
Changes the default filesystem encoding and errors mode to ‘mbcs’ and ‘replace’ respectively, for consistency with versions of Python prior to 3.6. This is equivalent to defining the PYTHONLEGACYWINDOWSFSENCODING environment variable before launching Python. Availability: Windows. New in version 3.6: See PEP 529 for more details. | python.library.sys#sys._enablelegacywindowsfsencoding |
sys._getframe([depth])
Return a frame object from the call stack. If optional integer depth is given, return the frame object that many calls below the top of the stack. If that is deeper than the call stack, ValueError is raised. The default for depth is zero, returning the frame at the top of the call stack. Raises an auditing event sys._getframe with no arguments. CPython implementation detail: This function should be used for internal and specialized purposes only. It is not guaranteed to exist in all implementations of Python. | python.library.sys#sys._getframe |
sys._xoptions
A dictionary of the various implementation-specific flags passed through the -X command-line option. Option names are either mapped to their values, if given explicitly, or to True. Example: $ ./python -Xa=b -Xc
Python 3.2a3+ (py3k, Oct 16 2010, 20:14:50)
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> sys._xoptions
{'a': 'b', 'c': True}
CPython implementation detail: This is a CPython-specific way of accessing options passed through -X. Other implementations may export them through other means, or not at all. New in version 3.2. | python.library.sys#sys._xoptions |
sys.__breakpointhook__
sys.__displayhook__
sys.__excepthook__
sys.__unraisablehook__
These objects contain the original values of breakpointhook, displayhook, excepthook, and unraisablehook at the start of the program. They are saved so that breakpointhook, displayhook and excepthook, unraisablehook can be restored in case they happen to get replaced with broken or alternative objects. New in version 3.7: __breakpointhook__ New in version 3.8: __unraisablehook__ | python.library.sys#sys.__breakpointhook__ |
sys.__breakpointhook__
sys.__displayhook__
sys.__excepthook__
sys.__unraisablehook__
These objects contain the original values of breakpointhook, displayhook, excepthook, and unraisablehook at the start of the program. They are saved so that breakpointhook, displayhook and excepthook, unraisablehook can be restored in case they happen to get replaced with broken or alternative objects. New in version 3.7: __breakpointhook__ New in version 3.8: __unraisablehook__ | python.library.sys#sys.__displayhook__ |
sys.__breakpointhook__
sys.__displayhook__
sys.__excepthook__
sys.__unraisablehook__
These objects contain the original values of breakpointhook, displayhook, excepthook, and unraisablehook at the start of the program. They are saved so that breakpointhook, displayhook and excepthook, unraisablehook can be restored in case they happen to get replaced with broken or alternative objects. New in version 3.7: __breakpointhook__ New in version 3.8: __unraisablehook__ | python.library.sys#sys.__excepthook__ |
sys.__interactivehook__
When this attribute exists, its value is automatically called (with no arguments) when the interpreter is launched in interactive mode. This is done after the PYTHONSTARTUP file is read, so that you can set this hook there. The site module sets this.
Raises an auditing event cpython.run_interactivehook with the hook object as the argument when the hook is called on startup. New in version 3.4. | python.library.sys#sys.__interactivehook__ |
sys.__stdin__
sys.__stdout__
sys.__stderr__
These objects contain the original values of stdin, stderr and stdout at the start of the program. They are used during finalization, and could be useful to print to the actual standard stream no matter if the sys.std* object has been redirected. It can also be used to restore the actual files to known working file objects in case they have been overwritten with a broken object. However, the preferred way to do this is to explicitly save the previous stream before replacing it, and restore the saved object. Note Under some conditions stdin, stdout and stderr as well as the original values __stdin__, __stdout__ and __stderr__ can be None. It is usually the case for Windows GUI apps that aren’t connected to a console and Python apps started with pythonw. | python.library.sys#sys.__stderr__ |
sys.__stdin__
sys.__stdout__
sys.__stderr__
These objects contain the original values of stdin, stderr and stdout at the start of the program. They are used during finalization, and could be useful to print to the actual standard stream no matter if the sys.std* object has been redirected. It can also be used to restore the actual files to known working file objects in case they have been overwritten with a broken object. However, the preferred way to do this is to explicitly save the previous stream before replacing it, and restore the saved object. Note Under some conditions stdin, stdout and stderr as well as the original values __stdin__, __stdout__ and __stderr__ can be None. It is usually the case for Windows GUI apps that aren’t connected to a console and Python apps started with pythonw. | python.library.sys#sys.__stdin__ |
sys.__stdin__
sys.__stdout__
sys.__stderr__
These objects contain the original values of stdin, stderr and stdout at the start of the program. They are used during finalization, and could be useful to print to the actual standard stream no matter if the sys.std* object has been redirected. It can also be used to restore the actual files to known working file objects in case they have been overwritten with a broken object. However, the preferred way to do this is to explicitly save the previous stream before replacing it, and restore the saved object. Note Under some conditions stdin, stdout and stderr as well as the original values __stdin__, __stdout__ and __stderr__ can be None. It is usually the case for Windows GUI apps that aren’t connected to a console and Python apps started with pythonw. | python.library.sys#sys.__stdout__ |
sys.__breakpointhook__
sys.__displayhook__
sys.__excepthook__
sys.__unraisablehook__
These objects contain the original values of breakpointhook, displayhook, excepthook, and unraisablehook at the start of the program. They are saved so that breakpointhook, displayhook and excepthook, unraisablehook can be restored in case they happen to get replaced with broken or alternative objects. New in version 3.7: __breakpointhook__ New in version 3.8: __unraisablehook__ | python.library.sys#sys.__unraisablehook__ |
sysconfig — Provide access to Python’s configuration information New in version 3.2. Source code: Lib/sysconfig.py The sysconfig module provides access to Python’s configuration information like the list of installation paths and the configuration variables relevant for the current platform. Configuration variables A Python distribution contains a Makefile and a pyconfig.h header file that are necessary to build both the Python binary itself and third-party C extensions compiled using distutils. sysconfig puts all variables found in these files in a dictionary that can be accessed using get_config_vars() or get_config_var(). Notice that on Windows, it’s a much smaller set.
sysconfig.get_config_vars(*args)
With no arguments, return a dictionary of all configuration variables relevant for the current platform. With arguments, return a list of values that result from looking up each argument in the configuration variable dictionary. For each argument, if the value is not found, return None.
sysconfig.get_config_var(name)
Return the value of a single variable name. Equivalent to get_config_vars().get(name). If name is not found, return None.
Example of usage: >>> import sysconfig
>>> sysconfig.get_config_var('Py_ENABLE_SHARED')
0
>>> sysconfig.get_config_var('LIBDIR')
'/usr/local/lib'
>>> sysconfig.get_config_vars('AR', 'CXX')
['ar', 'g++']
Installation paths Python uses an installation scheme that differs depending on the platform and on the installation options. These schemes are stored in sysconfig under unique identifiers based on the value returned by os.name. Every new component that is installed using distutils or a Distutils-based system will follow the same scheme to copy its file in the right places. Python currently supports seven schemes:
posix_prefix: scheme for POSIX platforms like Linux or Mac OS X. This is the default scheme used when Python or a component is installed.
posix_home: scheme for POSIX platforms used when a home option is used upon installation. This scheme is used when a component is installed through Distutils with a specific home prefix.
posix_user: scheme for POSIX platforms used when a component is installed through Distutils and the user option is used. This scheme defines paths located under the user home directory.
nt: scheme for NT platforms like Windows.
nt_user: scheme for NT platforms, when the user option is used. Each scheme is itself composed of a series of paths and each path has a unique identifier. Python currently uses eight paths:
stdlib: directory containing the standard Python library files that are not platform-specific.
platstdlib: directory containing the standard Python library files that are platform-specific.
platlib: directory for site-specific, platform-specific files.
purelib: directory for site-specific, non-platform-specific files.
include: directory for non-platform-specific header files.
platinclude: directory for platform-specific header files.
scripts: directory for script files.
data: directory for data files. sysconfig provides some functions to determine these paths.
sysconfig.get_scheme_names()
Return a tuple containing all schemes currently supported in sysconfig.
sysconfig.get_path_names()
Return a tuple containing all path names currently supported in sysconfig.
sysconfig.get_path(name[, scheme[, vars[, expand]]])
Return an installation path corresponding to the path name, from the install scheme named scheme. name has to be a value from the list returned by get_path_names(). sysconfig stores installation paths corresponding to each path name, for each platform, with variables to be expanded. For instance the stdlib path for the nt scheme is: {base}/Lib. get_path() will use the variables returned by get_config_vars() to expand the path. All variables have default values for each platform so one may call this function and get the default value. If scheme is provided, it must be a value from the list returned by get_scheme_names(). Otherwise, the default scheme for the current platform is used. If vars is provided, it must be a dictionary of variables that will update the dictionary return by get_config_vars(). If expand is set to False, the path will not be expanded using the variables. If name is not found, return None.
sysconfig.get_paths([scheme[, vars[, expand]]])
Return a dictionary containing all installation paths corresponding to an installation scheme. See get_path() for more information. If scheme is not provided, will use the default scheme for the current platform. If vars is provided, it must be a dictionary of variables that will update the dictionary used to expand the paths. If expand is set to false, the paths will not be expanded. If scheme is not an existing scheme, get_paths() will raise a KeyError.
Other functions
sysconfig.get_python_version()
Return the MAJOR.MINOR Python version number as a string. Similar to '%d.%d' % sys.version_info[:2].
sysconfig.get_platform()
Return a string that identifies the current platform. This is used mainly to distinguish platform-specific build directories and platform-specific built distributions. Typically includes the OS name and version and the architecture (as supplied by ‘os.uname()’), although the exact information included depends on the OS; e.g., on Linux, the kernel version isn’t particularly important. Examples of returned values: linux-i586 linux-alpha (?) solaris-2.6-sun4u Windows will return one of: win-amd64 (64bit Windows on AMD64, aka x86_64, Intel64, and EM64T) win32 (all others - specifically, sys.platform is returned) Mac OS X can return: macosx-10.6-ppc macosx-10.4-ppc64 macosx-10.3-i386 macosx-10.4-fat For other non-POSIX platforms, currently just returns sys.platform.
sysconfig.is_python_build()
Return True if the running Python interpreter was built from source and is being run from its built location, and not from a location resulting from e.g. running make install or installing via a binary installer.
sysconfig.parse_config_h(fp[, vars])
Parse a config.h-style file. fp is a file-like object pointing to the config.h-like file. A dictionary containing name/value pairs is returned. If an optional dictionary is passed in as the second argument, it is used instead of a new dictionary, and updated with the values read in the file.
sysconfig.get_config_h_filename()
Return the path of pyconfig.h.
sysconfig.get_makefile_filename()
Return the path of Makefile.
Using sysconfig as a script You can use sysconfig as a script with Python’s -m option: $ python -m sysconfig
Platform: "macosx-10.4-i386"
Python version: "3.2"
Current installation scheme: "posix_prefix"
Paths:
data = "/usr/local"
include = "/Users/tarek/Dev/svn.python.org/py3k/Include"
platinclude = "."
platlib = "/usr/local/lib/python3.2/site-packages"
platstdlib = "/usr/local/lib/python3.2"
purelib = "/usr/local/lib/python3.2/site-packages"
scripts = "/usr/local/bin"
stdlib = "/usr/local/lib/python3.2"
Variables:
AC_APPLE_UNIVERSAL_BUILD = "0"
AIX_GENUINE_CPLUSPLUS = "0"
AR = "ar"
ARFLAGS = "rc"
...
This call will print in the standard output the information returned by get_platform(), get_python_version(), get_path() and get_config_vars(). | python.library.sysconfig |
sysconfig.get_config_h_filename()
Return the path of pyconfig.h. | python.library.sysconfig#sysconfig.get_config_h_filename |
sysconfig.get_config_var(name)
Return the value of a single variable name. Equivalent to get_config_vars().get(name). If name is not found, return None. | python.library.sysconfig#sysconfig.get_config_var |
sysconfig.get_config_vars(*args)
With no arguments, return a dictionary of all configuration variables relevant for the current platform. With arguments, return a list of values that result from looking up each argument in the configuration variable dictionary. For each argument, if the value is not found, return None. | python.library.sysconfig#sysconfig.get_config_vars |
sysconfig.get_makefile_filename()
Return the path of Makefile. | python.library.sysconfig#sysconfig.get_makefile_filename |
sysconfig.get_path(name[, scheme[, vars[, expand]]])
Return an installation path corresponding to the path name, from the install scheme named scheme. name has to be a value from the list returned by get_path_names(). sysconfig stores installation paths corresponding to each path name, for each platform, with variables to be expanded. For instance the stdlib path for the nt scheme is: {base}/Lib. get_path() will use the variables returned by get_config_vars() to expand the path. All variables have default values for each platform so one may call this function and get the default value. If scheme is provided, it must be a value from the list returned by get_scheme_names(). Otherwise, the default scheme for the current platform is used. If vars is provided, it must be a dictionary of variables that will update the dictionary return by get_config_vars(). If expand is set to False, the path will not be expanded using the variables. If name is not found, return None. | python.library.sysconfig#sysconfig.get_path |
sysconfig.get_paths([scheme[, vars[, expand]]])
Return a dictionary containing all installation paths corresponding to an installation scheme. See get_path() for more information. If scheme is not provided, will use the default scheme for the current platform. If vars is provided, it must be a dictionary of variables that will update the dictionary used to expand the paths. If expand is set to false, the paths will not be expanded. If scheme is not an existing scheme, get_paths() will raise a KeyError. | python.library.sysconfig#sysconfig.get_paths |
sysconfig.get_path_names()
Return a tuple containing all path names currently supported in sysconfig. | python.library.sysconfig#sysconfig.get_path_names |
sysconfig.get_platform()
Return a string that identifies the current platform. This is used mainly to distinguish platform-specific build directories and platform-specific built distributions. Typically includes the OS name and version and the architecture (as supplied by ‘os.uname()’), although the exact information included depends on the OS; e.g., on Linux, the kernel version isn’t particularly important. Examples of returned values: linux-i586 linux-alpha (?) solaris-2.6-sun4u Windows will return one of: win-amd64 (64bit Windows on AMD64, aka x86_64, Intel64, and EM64T) win32 (all others - specifically, sys.platform is returned) Mac OS X can return: macosx-10.6-ppc macosx-10.4-ppc64 macosx-10.3-i386 macosx-10.4-fat For other non-POSIX platforms, currently just returns sys.platform. | python.library.sysconfig#sysconfig.get_platform |
sysconfig.get_python_version()
Return the MAJOR.MINOR Python version number as a string. Similar to '%d.%d' % sys.version_info[:2]. | python.library.sysconfig#sysconfig.get_python_version |
sysconfig.get_scheme_names()
Return a tuple containing all schemes currently supported in sysconfig. | python.library.sysconfig#sysconfig.get_scheme_names |
sysconfig.is_python_build()
Return True if the running Python interpreter was built from source and is being run from its built location, and not from a location resulting from e.g. running make install or installing via a binary installer. | python.library.sysconfig#sysconfig.is_python_build |
sysconfig.parse_config_h(fp[, vars])
Parse a config.h-style file. fp is a file-like object pointing to the config.h-like file. A dictionary containing name/value pairs is returned. If an optional dictionary is passed in as the second argument, it is used instead of a new dictionary, and updated with the values read in the file. | python.library.sysconfig#sysconfig.parse_config_h |
syslog — Unix syslog library routines This module provides an interface to the Unix syslog library routines. Refer to the Unix manual pages for a detailed description of the syslog facility. This module wraps the system syslog family of routines. A pure Python library that can speak to a syslog server is available in the logging.handlers module as SysLogHandler. The module defines the following functions:
syslog.syslog(message)
syslog.syslog(priority, message)
Send the string message to the system logger. A trailing newline is added if necessary. Each message is tagged with a priority composed of a facility and a level. The optional priority argument, which defaults to LOG_INFO, determines the message priority. If the facility is not encoded in priority using logical-or (LOG_INFO | LOG_USER), the value given in the openlog() call is used. If openlog() has not been called prior to the call to syslog(), openlog() will be called with no arguments. Raises an auditing event syslog.syslog with arguments priority, message.
syslog.openlog([ident[, logoption[, facility]]])
Logging options of subsequent syslog() calls can be set by calling openlog(). syslog() will call openlog() with no arguments if the log is not currently open. The optional ident keyword argument is a string which is prepended to every message, and defaults to sys.argv[0] with leading path components stripped. The optional logoption keyword argument (default is 0) is a bit field – see below for possible values to combine. The optional facility keyword argument (default is LOG_USER) sets the default facility for messages which do not have a facility explicitly encoded. Raises an auditing event syslog.openlog with arguments ident, logoption, facility. Changed in version 3.2: In previous versions, keyword arguments were not allowed, and ident was required. The default for ident was dependent on the system libraries, and often was python instead of the name of the Python program file.
syslog.closelog()
Reset the syslog module values and call the system library closelog(). This causes the module to behave as it does when initially imported. For example, openlog() will be called on the first syslog() call (if openlog() hasn’t already been called), and ident and other openlog() parameters are reset to defaults. Raises an auditing event syslog.closelog with no arguments.
syslog.setlogmask(maskpri)
Set the priority mask to maskpri and return the previous mask value. Calls to syslog() with a priority level not set in maskpri are ignored. The default is to log all priorities. The function LOG_MASK(pri) calculates the mask for the individual priority pri. The function LOG_UPTO(pri) calculates the mask for all priorities up to and including pri. Raises an auditing event syslog.setlogmask with argument maskpri.
The module defines the following constants: Priority levels (high to low):
LOG_EMERG, LOG_ALERT, LOG_CRIT, LOG_ERR, LOG_WARNING, LOG_NOTICE, LOG_INFO, LOG_DEBUG. Facilities:
LOG_KERN, LOG_USER, LOG_MAIL, LOG_DAEMON, LOG_AUTH, LOG_LPR, LOG_NEWS, LOG_UUCP, LOG_CRON, LOG_SYSLOG, LOG_LOCAL0 to LOG_LOCAL7, and, if defined in <syslog.h>, LOG_AUTHPRIV. Log options:
LOG_PID, LOG_CONS, LOG_NDELAY, and, if defined in <syslog.h>, LOG_ODELAY, LOG_NOWAIT, and LOG_PERROR. Examples Simple example A simple set of examples: import syslog
syslog.syslog('Processing started')
if error:
syslog.syslog(syslog.LOG_ERR, 'Processing started')
An example of setting some log options, these would include the process ID in logged messages, and write the messages to the destination facility used for mail logging: syslog.openlog(logoption=syslog.LOG_PID, facility=syslog.LOG_MAIL)
syslog.syslog('E-mail processing initiated...') | python.library.syslog |
syslog.closelog()
Reset the syslog module values and call the system library closelog(). This causes the module to behave as it does when initially imported. For example, openlog() will be called on the first syslog() call (if openlog() hasn’t already been called), and ident and other openlog() parameters are reset to defaults. Raises an auditing event syslog.closelog with no arguments. | python.library.syslog#syslog.closelog |
syslog.openlog([ident[, logoption[, facility]]])
Logging options of subsequent syslog() calls can be set by calling openlog(). syslog() will call openlog() with no arguments if the log is not currently open. The optional ident keyword argument is a string which is prepended to every message, and defaults to sys.argv[0] with leading path components stripped. The optional logoption keyword argument (default is 0) is a bit field – see below for possible values to combine. The optional facility keyword argument (default is LOG_USER) sets the default facility for messages which do not have a facility explicitly encoded. Raises an auditing event syslog.openlog with arguments ident, logoption, facility. Changed in version 3.2: In previous versions, keyword arguments were not allowed, and ident was required. The default for ident was dependent on the system libraries, and often was python instead of the name of the Python program file. | python.library.syslog#syslog.openlog |
syslog.setlogmask(maskpri)
Set the priority mask to maskpri and return the previous mask value. Calls to syslog() with a priority level not set in maskpri are ignored. The default is to log all priorities. The function LOG_MASK(pri) calculates the mask for the individual priority pri. The function LOG_UPTO(pri) calculates the mask for all priorities up to and including pri. Raises an auditing event syslog.setlogmask with argument maskpri. | python.library.syslog#syslog.setlogmask |
syslog.syslog(message)
syslog.syslog(priority, message)
Send the string message to the system logger. A trailing newline is added if necessary. Each message is tagged with a priority composed of a facility and a level. The optional priority argument, which defaults to LOG_INFO, determines the message priority. If the facility is not encoded in priority using logical-or (LOG_INFO | LOG_USER), the value given in the openlog() call is used. If openlog() has not been called prior to the call to syslog(), openlog() will be called with no arguments. Raises an auditing event syslog.syslog with arguments priority, message. | python.library.syslog#syslog.syslog |
exception SystemError
Raised when the interpreter finds an internal error, but the situation does not look so serious to cause it to abandon all hope. The associated value is a string indicating what went wrong (in low-level terms). You should report this to the author or maintainer of your Python interpreter. Be sure to report the version of the Python interpreter (sys.version; it is also printed at the start of an interactive Python session), the exact error message (the exception’s associated value) and if possible the source of the program that triggered the error. | python.library.exceptions#SystemError |
exception SystemExit
This exception is raised by the sys.exit() function. It inherits from BaseException instead of Exception so that it is not accidentally caught by code that catches Exception. This allows the exception to properly propagate up and cause the interpreter to exit. When it is not handled, the Python interpreter exits; no stack traceback is printed. The constructor accepts the same optional argument passed to sys.exit(). If the value is an integer, it specifies the system exit status (passed to C’s exit() function); if it is None, the exit status is zero; if it has another type (such as a string), the object’s value is printed and the exit status is one. A call to sys.exit() is translated into an exception so that clean-up handlers (finally clauses of try statements) can be executed, and so that a debugger can execute a script without running the risk of losing control. The os._exit() function can be used if it is absolutely positively necessary to exit immediately (for example, in the child process after a call to os.fork()).
code
The exit status or error message that is passed to the constructor. (Defaults to None.) | python.library.exceptions#SystemExit |
code
The exit status or error message that is passed to the constructor. (Defaults to None.) | python.library.exceptions#SystemExit.code |
exception TabError
Raised when indentation contains an inconsistent use of tabs and spaces. This is a subclass of IndentationError. | python.library.exceptions#TabError |
tabnanny — Detection of ambiguous indentation Source code: Lib/tabnanny.py For the time being this module is intended to be called as a script. However it is possible to import it into an IDE and use the function check() described below. Note The API provided by this module is likely to change in future releases; such changes may not be backward compatible.
tabnanny.check(file_or_dir)
If file_or_dir is a directory and not a symbolic link, then recursively descend the directory tree named by file_or_dir, checking all .py files along the way. If file_or_dir is an ordinary Python source file, it is checked for whitespace related problems. The diagnostic messages are written to standard output using the print() function.
tabnanny.verbose
Flag indicating whether to print verbose messages. This is incremented by the -v option if called as a script.
tabnanny.filename_only
Flag indicating whether to print only the filenames of files containing whitespace related problems. This is set to true by the -q option if called as a script.
exception tabnanny.NannyNag
Raised by process_tokens() if detecting an ambiguous indent. Captured and handled in check().
tabnanny.process_tokens(tokens)
This function is used by check() to process tokens generated by the tokenize module.
See also
Module tokenize
Lexical scanner for Python source code. | python.library.tabnanny |
tabnanny.check(file_or_dir)
If file_or_dir is a directory and not a symbolic link, then recursively descend the directory tree named by file_or_dir, checking all .py files along the way. If file_or_dir is an ordinary Python source file, it is checked for whitespace related problems. The diagnostic messages are written to standard output using the print() function. | python.library.tabnanny#tabnanny.check |
tabnanny.filename_only
Flag indicating whether to print only the filenames of files containing whitespace related problems. This is set to true by the -q option if called as a script. | python.library.tabnanny#tabnanny.filename_only |
exception tabnanny.NannyNag
Raised by process_tokens() if detecting an ambiguous indent. Captured and handled in check(). | python.library.tabnanny#tabnanny.NannyNag |
tabnanny.process_tokens(tokens)
This function is used by check() to process tokens generated by the tokenize module. | python.library.tabnanny#tabnanny.process_tokens |
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