PYTHON(1)

👑 PYTHON(1) 👑

ok bestie, welcome to the manual page for Python — specifically the vtkPython 3.9.0+ situation, a.k.a. the VTK-Wrapper for Python. It lives in the User Commands section of the manual, and it's genuinely iconic. Sit down, grab a strawberry 🍓, and let's get into it.

🌸 NAME 🌸

Python — manual page for vtkPython 3.9.0+ : VTK-Wrapper for Python

✨ DESCRIPTION ✨

okay so here's the whole vibe, the entire layout, the moment:

usage: /usr/bin/../lib/x86_64-linux-gnu/vtkpython [option] ... [-c cmd |
-m mod | file | -] [arg] ...

That's the shape of it. Options, arguments, and (yes) the corresponding environment variables. Let's go through every single one, no skipping, periodt. 💅

• -b — issue warnings about str(bytes_instance), str(bytearray_instance) and comparing bytes/bytearray with str. And if you're feeling extra, -bb issues errors instead. 💀
• -B — don't write .pyc files on import; also works via PYTHONDONTWRITEBYTECODE=x
• -c cmd — program passed in as string (this terminates the option list, so be careful bestie)
• -d — debug output from parser; also PYTHONDEBUG=x
• -E — ignore PYTHON* environment variables (such as PYTHONPATH)
• -h — print this help message and exit (also --help)
• -i — inspect interactively after running script; forces a prompt even if stdin does not appear to be a terminal; also PYTHONINSPECT=x
• -I — isolate Python from the user's environment (implies -E and -s)
• -m mod — run library module as a script (terminates the option list)
• -O — remove assert and __debug__-dependent statements; add .opt-1 before the .pyc extension; also PYTHONOPTIMIZE=x
• -OO — do the -O changes and also discard docstrings; add .opt-2 before the .pyc extension
• -q — don't print version and copyright messages on interactive startup
• -s — don't add the user site directory to sys.path; also PYTHONNOUSERSITE
• -S — don't imply import site on initialization
• -u — force the stdout and stderr streams to be unbuffered; this option has no effect on stdin; also PYTHONUNBUFFERED=x
• -v — verbose (trace import statements); also PYTHONVERBOSE=x. You can supply it multiple times to increase verbosity 🌈
• -V — print the Python version number and exit (also --version). When given twice, print more information about the build
• -W arg — warning control; arg is action:message:category:module:lineno; also PYTHONWARNINGS=arg
• -x — skip first line of source, allowing use of non-Unix forms of #!cmd
• -X opt — set an implementation-specific option. The following options are available:
  • -X faulthandler: enable faulthandler
  • -X oldparser: enable the traditional LL(1) parser; also PYTHONOLDPARSER
  • -X showrefcount: output the total reference count and number of used memory blocks when the program finishes or after each statement in the interactive interpreter. This only works on debug builds
  • -X tracemalloc: start tracing Python memory allocations using the tracemalloc module. By default, only the most recent frame is stored in a traceback of a trace. Use -X tracemalloc=NFRAME to start tracing with a traceback limit of NFRAME frames
  • -X importtime: show how long each import takes. It shows module name, cumulative time (including nested imports) and self time (excluding nested imports). Note that its output may be broken in multi-threaded application. Typical usage is python3 -X importtime -c 'import asyncio'
  • -X dev: enable CPython's "development mode", introducing additional runtime checks which are too expensive to be enabled by default. Effect of the developer mode:
    • Add default warning filter, as -W default
    • Install debug hooks on memory allocators: see the PyMem_SetupDebugHooks() C function
    • Enable the faulthandler module to dump the Python traceback on a crash
    • Enable asyncio debug mode
    • Set the dev_mode attribute of sys.flags to True
    • io.IOBase destructor logs close() exceptions
  • -X utf8: enable UTF-8 mode for operating system interfaces, overriding the default locale-aware mode. -X utf8=0 explicitly disables UTF-8 mode (even when it would otherwise activate automatically)
  • -X pycache_prefix=PATH: enable writing .pyc files to a parallel tree rooted at the given directory instead of to the code tree
• --check-hash-based-pycs always|default|never — control how Python invalidates hash-based .pyc files
• file — program read from script file
• - — program read from stdin (default; interactive mode if a tty)
• arg ... — arguments passed to program in sys.argv[1:]

🦋 Other environment variables 🦋

these ones live outside the flags, they're just vibing in your shell 🌈

• PYTHONSTARTUP: file executed on interactive startup (no default)
• PYTHONPATH: ':'-separated list of directories prefixed to the default module search path. The result is sys.path.
• PYTHONHOME: alternate <prefix> directory (or <prefix>:<exec_prefix>). The default module search path uses <prefix>/lib/pythonX.X.
• PYTHONPLATLIBDIR: override sys.platlibdir.
• PYTHONCASEOK: ignore case in 'import' statements (Windows).
• PYTHONUTF8: if set to 1, enable the UTF-8 mode.
• PYTHONIOENCODING: Encoding[:errors] used for stdin/stdout/stderr.
• PYTHONFAULTHANDLER: dump the Python traceback on fatal errors.
• PYTHONHASHSEED: if this variable is set to 'random', a random value is used to seed the hashes of str and bytes objects. It can also be set to an integer in the range [0,4294967295] to get hash values with a predictable seed.
• PYTHONMALLOC: set the Python memory allocators and/or install debug hooks on Python memory allocators. Use PYTHONMALLOC=debug to install debug hooks.
• PYTHONCOERCECLOCALE: if this variable is set to 0, it disables the locale coercion behavior. Use PYTHONCOERCECLOCALE=warn to request display of locale coercion and locale compatibility warnings on stderr.
• PYTHONBREAKPOINT: if this variable is set to 0, it disables the default debugger. It can be set to the callable of your debugger of choice.
• PYTHONDEVMODE: enable the development mode.
• PYTHONPYCACHEPREFIX: root directory for bytecode cache (pyc) files.

🎀 SEE ALSO 🎀

The full documentation for Python is maintained as a Texinfo manual. If the info and Python programs are properly installed at your site, the command

info Python

should give you access to the complete manual. go get that lore bestie 🫶

and that's the whole page!! mwah 💖 this was Python 3.9.0+ from November 2020, filed under PYTHON(1) — slay, no cap, you ate this manual ✨👑