# sys - pydoc - phpman Help on built-in module sys: ## NAME sys ## MODULE REFERENCE The following documentation is automatically generated from the Python source files. It may be incomplete, incorrect or include features that are considered implementation detail and may vary between Python implementations. When in doubt, consult the module reference at the location listed above. ## DESCRIPTION This module provides access to some objects used or maintained by the interpreter and to functions that interact strongly with the interpreter. Dynamic objects: argv -- command line arguments; argv[0] is the script pathname if known path -- module search path; path[0] is the script directory, else '' modules -- dictionary of loaded modules displayhook -- called to show results in an interactive session excepthook -- called to handle any uncaught exception other than SystemExit To customize printing in an interactive session or to install a custom top-level exception handler, assign other functions to replace these. stdin -- standard input file object; used by input() stdout -- standard output file object; used by print() stderr -- standard error object; used for error messages By assigning other file objects (or objects that behave like files) to these, it is possible to redirect all of the interpreter's I/O. last_type -- type of last uncaught exception last_value -- value of last uncaught exception last_traceback -- traceback of last uncaught exception These three are only available in an interactive session after a traceback has been printed. Static objects: builtin_module_names -- tuple of module names built into this interpreter copyright -- copyright notice pertaining to this interpreter exec_prefix -- prefix used to find the machine-specific Python library executable -- absolute path of the executable binary of the Python interpreter float_info -- a named tuple with information about the float implementation. float_repr_style -- string indicating the style of repr() output for floats hash_info -- a named tuple with information about the hash algorithm. hexversion -- version information encoded as a single integer implementation -- Python implementation information. int_info -- a named tuple with information about the int implementation. maxsize -- the largest supported length of containers. maxunicode -- the value of the largest Unicode code point platform -- platform identifier prefix -- prefix used to find the Python library thread_info -- a named tuple with information about the thread implementation. version -- the version of this interpreter as a string version_info -- version information as a named tuple __stdin__ -- the original stdin; don't touch! __stdout__ -- the original stdout; don't touch! __stderr__ -- the original stderr; don't touch! __displayhook__ -- the original displayhook; don't touch! __excepthook__ -- the original excepthook; don't touch! Functions: ### displayhook ### excepthook ### exc_info ### exit ### getdlopenflags ### getprofile ### getrefcount ### getrecursionlimit ### getsizeof ### gettrace ### setdlopenflags ### setprofile ### setrecursionlimit ### settrace ## FUNCTIONS __breakpointhook__ = breakpointhook(...) breakpointhook(*args, **kws) This hook function is called by built-in breakpoint(). __displayhook__ = displayhook(object, /) Print an object to sys.stdout and also save it in builtins._ __excepthook__ = excepthook(exctype, value, traceback, /) Handle an exception by displaying it with a traceback on sys.stderr. __unraisablehook__ = unraisablehook(unraisable, /) Handle an unraisable exception. 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. ### addaudithook Adds a new audit hook callback. ### audit audit(event, *args) Passes the event to any audit hooks that are attached. ### breakpointhook breakpointhook(*args, **kws) This hook function is called by built-in breakpoint(). ### call_tracing Call func(*args), while tracing is enabled. The tracing state is saved, and restored afterwards. This is intended to be called from a debugger from a checkpoint, to recursively debug some other code. ### displayhook Print an object to sys.stdout and also save it in builtins._ ### exc_info Return current exception information: (type, value, traceback). Return information about the most recent exception caught by an except clause in the current stack frame or in an older stack frame. ### exit Exit the interpreter by raising SystemExit(status). If the status is omitted or None, it defaults to zero (i.e., success). If the status is an integer, it will be used as the system exit status. If it is another kind of object, it will be printed and the system exit status will be one (i.e., failure). ### get_asyncgen_hooks Return the installed asynchronous generators hooks. This returns a namedtuple of the form (firstiter, finalizer). ### get_coroutine_origin_tracking_depth Check status of origin tracking for coroutine objects in this thread. ### get_int_max_str_digits Return the maximum string digits limit for non-binary int<->str conversions. ### getallocatedblocks Return the number of memory blocks currently allocated. ### getdefaultencoding Return the current default encoding used by the Unicode implementation. ### getdlopenflags Return the current value of the flags that are used for dlopen calls. The flag constants are defined in the os module. ### getfilesystemencodeerrors Return the error mode used Unicode to OS filename conversion. ### getfilesystemencoding Return the encoding used to convert Unicode filenames to OS filenames. ### getprofile Return the profiling function set with sys.setprofile. See the profiler chapter in the library manual. ### getrecursionlimit Return the current value of the recursion limit. The recursion limit is the maximum depth of the Python interpreter stack. This limit prevents infinite recursion from causing an overflow of the C stack and crashing Python. ### getrefcount Return the reference count of object. The count returned is generally one higher than you might expect, because it includes the (temporary) reference as an argument to getrefcount(). ### getsizeof getsizeof(object [, default]) -> int Return the size of object in bytes. ### getswitchinterval Return the current thread switch interval; see sys.setswitchinterval(). ### gettrace Return the global debug tracing function set with sys.settrace. See the debugger chapter in the library manual. ### intern ``Intern'' the given string. This enters the string in the (global) table of interned strings whose purpose is to speed up dictionary lookups. Return the string itself or the previously interned string object with the same value. ### is_finalizing Return True if Python is exiting. ### set_asyncgen_hooks set_asyncgen_hooks(* [, firstiter] [, finalizer]) Set a finalizer for async generators objects. ### set_coroutine_origin_tracking_depth Enable or disable origin tracking for coroutine objects in this thread. Coroutine objects will track 'depth' frames of traceback information about where they came from, available in their cr_origin attribute. Set a depth of 0 to disable. ### set_int_max_str_digits Set the maximum string digits limit for non-binary int<->str conversions. ### setdlopenflags Set the flags used by the interpreter for dlopen calls. This is used, for example, 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)](https://www.chedong.com/phpMan.php/man/sys.setdlopenflags/0/markdown). To share symbols across extension modules, call as sys.setdlopenflags(os.RTLD_GLOBAL). Symbolic names for the flag modules can be found in the os module (RTLD_xxx constants, e.g. os.RTLD_LAZY). ### setprofile setprofile(function) Set the profiling function. It will be called on each function call and return. See the profiler chapter in the library manual. ### setrecursionlimit Set the maximum depth of the Python interpreter stack to n. This limit prevents infinite recursion from causing an overflow of the C stack and crashing Python. The highest possible limit is platform- dependent. ### setswitchinterval Set the ideal thread switching delay inside the Python interpreter. The actual frequency of switching threads can be lower if the interpreter executes long sequences of uninterruptible code (this is implementation-specific and workload-dependent). The parameter must represent the desired switching delay in seconds A typical value is 0.005 (5 milliseconds). ### settrace settrace(function) Set the global debug tracing function. It will be called on each function call. See the debugger chapter in the library manual. ### unraisablehook Handle an unraisable exception. 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. ## DATA __stderr__ = <_io.TextIOWrapper name='' mode='w' encoding='utf... __stdin__ = <_io.TextIOWrapper name='' mode='r' encoding='utf-8... __stdout__ = <_io.TextIOWrapper name='' mode='w' encoding='utf... abiflags = '' api_version = 1013 argv = ['/usr/bin/pydoc3', 'sys'] base_exec_prefix = '/usr' base_prefix = '/usr' builtin_module_names = ('_abc', '_ast', '_bisect', '_blake2', '_codecs... byteorder = 'little' copyright = 'Copyright (c) 2001-2023 Python Software Foundati...ematis... dont_write_bytecode = False exec_prefix = '/usr' executable = '/usr/bin/python3.10' flags = sys.flags(debug=0, inspect=0, interactive=0, opt..., warn_defa... float_info = sys.float_info(max=1.7976931348623157e+308, max_...epsilo... float_repr_style = 'short' hash_info = sys.hash_info(width=64, modulus=2305843009213693...iphash2... hexversion = 50990320 implementation = namespace(name='cpython', cache_tag='cpython-310...xv... int_info = sys.int_info(bits_per_digit=30, sizeof_digit=4, ..._str_dig... maxsize = 9223372036854775807 maxunicode = 1114111 meta_path = [, , '_a... orig_argv = ['/usr/bin/python3.10', '/usr/bin/pydoc3', 'sys'] path = ['/home/chedong/chedong.com', '/usr/lib/python310.zip', '/usr/l... path_hooks = [, stdin = <_io.TextIOWrapper name='' mode='r' encoding='utf-8'> stdlib_module_names = frozenset({'__future__', '_abc', '_aix_support',... stdout = <_io.TextIOWrapper name='' mode='w' encoding='utf-8'> thread_info = sys.thread_info(name='pthread', lock='semaphore', versio... version = '3.10.12 (main, Mar 3 2026, 11:56:32) [GCC 11.4.0]' version_info = sys.version_info(major=3, minor=10, micro=12, releasele... warnoptions = [] ## FILE (built-in)