Chapter 1. Command line and environment 10 Python Setup and Usage, Release 3.9.5 If$_{PYTHONHASHSEED}$ is set to an integer value, it is used as a fixed seed for generating the hash() of the types covered by the hash randomization. Its purpose is to allow repeatable hashing, such as for selftests for the interpreter itself, or to allow a cluster of python processes to share hash values. The integer must be a decimal number in the range [0,4294967295]. Specifying the value 0 will disable hash randomization. New in version 3.2.3. If this is set before running the interpreter, it overrides the encoding used for stdin/stdout/stderr, in the syn- tax$_{encodingname:errorhandler}$ . Both the$_{encodingname}$and the$_{:errorhandler}$parts are optional and have the same meaning as in str.encode() . For stderr, the$_{:errorhandler}$part is ignored; the handler will always be$_{'backslashreplace'}$ . Changed in version 3.4: The encodingname part is now optional. Changed in version 3.6: On Windows, the encoding specified by this variable is ignored for interactive console buffers unless PYTHONLEGACYWINDOWSSTDIO is also specified. Files and pipes redirected through the standard streams are not affected. If this is set, Python won’t add the$_{user site-packages directory}$ to$_{sys.path}$ . See also: PEP 370 – Per user site-packages directory Defines the$_{user base directory}$, which is used to compute the path of the$_{user site-packages}$ directory and Distutils installation paths for$_{python setup.py install --user}$ . See also: PEP 370 – Per user site-packages directory If this environment variable is set,$_{sys.argv[0]}$ will be set to its value instead of the value got through the C runtime. Only works on Mac OS X. This is equivalent to the$_{-W}$option. If set to a comma separated string, it is equivalent to specifying$_{-W}$multiple times, with filters later in the list taking precedence over those earlier in the list. The simplest settings apply a particular action unconditionally to all warnings emitted by a process (even those that are otherwise ignored by default): PYTHONWARNINGS =default # Warn once per call location PYTHONWARNINGS =error # Convert to exceptions PYTHONWARNINGS =always # Warn every time PYTHONWARNINGS =module # Warn once per calling module PYTHONWARNINGS =once # Warn once per Python process PYTHONWARNINGS =ignore # Never warn See warning-filter and describing-warning-filters for more details. If this environment variable is set to a non-empty string,$_{faulthandler.enable()}$ is called at startup: install a handler for SIGSEGV , SIGFPE , SIGABRT , SIGBUS and SIGILL signals to dump the Python traceback. This is equivalent to$_{-X}$$_{faulthandler}$ option. New in version 3.3. If this environment variable is set to a non-empty string, start tracing Python memory allocations using the PYTHONTRACEMALLOC PYTHONFAULTHANDLER PYTHONWARNINGS PYTHONEXECUTABLE PYTHONUSERBASE PYTHONNOUSERSITE PYTHONIOENCODING