Some environment variables are missing from `--help-env`

[devdanzin]

Documentation

While looking for ways to control the new REPL, I found that PYTHON_BASIC_REPL influences it, but is not present in the output of --help-env.

Here's a list of environment variables that are present in the documentation but missing from --help-env in initconfig.c:

• PYTHONASYNCIODEBUG
• PYTHONDUMPREFS
• PYTHONDUMPREFSFILE
• PYTHONEXECUTABLE
• PYTHONLEGACYWINDOWSFSENCODING
• PYTHONLEGACYWINDOWSSTDIO
• PYTHONMALLOCSTATS
• PYTHONUSERBASE
• PYTHON_BASIC_REPL
• PYTHON_PERF_JIT_SUPPORT

The environment variable PYTHONSTATS is present in initconfig.c but missing from the docs.

Here's the part of initconfig.c with the content of --help-env:

cpython/Python/initconfig.c

Lines 234 to 301 in d25954d

	/* Envvars that don't have equivalent command-line options are listed first */
	static const char usage_envvars[] =
	"Environment variables that change behavior:\n"
	"PYTHONSTARTUP : file executed on interactive startup (no default)\n"
	"PYTHONPATH : '%lc'-separated list of directories prefixed to the\n"
	" default module search path. The result is sys.path.\n"
	"PYTHONHOME : alternate <prefix> directory (or <prefix>%lc<exec_prefix>).\n"
	" The default module search path uses %s.\n"
	"PYTHONPLATLIBDIR: override sys.platlibdir\n"
	"PYTHONCASEOK : ignore case in 'import' statements (Windows)\n"
	"PYTHONIOENCODING: encoding[:errors] used for stdin/stdout/stderr\n"
	"PYTHONHASHSEED : if this variable is set to 'random', a random value is used\n"
	" to seed the hashes of str and bytes objects. It can also be\n"
	" set to an integer in the range [0,4294967295] to get hash\n"
	" values with a predictable seed.\n"
	"PYTHONMALLOC : set the Python memory allocators and/or install debug hooks\n"
	" on Python memory allocators. Use PYTHONMALLOC=debug to\n"
	" install debug hooks.\n"
	"PYTHONCOERCECLOCALE: if this variable is set to 0, it disables the locale\n"
	" coercion behavior. Use PYTHONCOERCECLOCALE=warn to request\n"
	" display of locale coercion and locale compatibility warnings\n"
	" on stderr.\n"
	"PYTHONBREAKPOINT: if this variable is set to 0, it disables the default\n"
	" debugger. It can be set to the callable of your debugger of\n"
	" choice.\n"
	"PYTHON_COLORS : if this variable is set to 1, the interpreter will colorize\n"
	" various kinds of output. Setting it to 0 deactivates\n"
	" this behavior.\n"
	"PYTHON_HISTORY : the location of a .python_history file.\n"
	"\n"
	"These variables have equivalent command-line options (see --help for details):\n"
	"PYTHON_CPU_COUNT: override the return value of os.cpu_count() (-X cpu_count)\n"
	"PYTHONDEBUG : enable parser debug mode (-d)\n"
	"PYTHONDEVMODE : enable Python Development Mode (-X dev)\n"
	"PYTHONDONTWRITEBYTECODE: don't write .pyc files (-B)\n"
	"PYTHONFAULTHANDLER: dump the Python traceback on fatal errors (-X faulthandler)\n"
	"PYTHON_FROZEN_MODULES: whether to use frozen modules; the default is \"on\"\n"
	" for installed Python and \"off\" for a local build\n"
	" (-X frozen_modules)\n"
	#ifdef Py_GIL_DISABLED
	"PYTHON_GIL : when set to 0, disables the GIL (-X gil)\n"
	#endif
	"PYTHONINSPECT : inspect interactively after running script (-i)\n"
	"PYTHONINTMAXSTRDIGITS: limit the size of int<->str conversions;\n"
	" 0 disables the limit (-X int_max_str_digits=N)\n"
	"PYTHONNODEBUGRANGES: don't include extra location information in code objects\n"
	" (-X no_debug_ranges)\n"
	"PYTHONNOUSERSITE: disable user site directory (-s)\n"
	"PYTHONOPTIMIZE : enable level 1 optimizations (-O)\n"
	"PYTHONPERFSUPPORT: support the Linux \"perf\" profiler (-X perf)\n"
	#ifdef Py_DEBUG
	"PYTHON_PRESITE: import this module before site (-X presite)\n"
	#endif
	"PYTHONPROFILEIMPORTTIME: show how long each import takes (-X importtime)\n"
	"PYTHONPYCACHEPREFIX: root directory for bytecode cache (pyc) files\n"
	" (-X pycache_prefix)\n"
	"PYTHONSAFEPATH : don't prepend a potentially unsafe path to sys.path.\n"
	#ifdef Py_STATS
	"PYTHONSTATS : turns on statistics gathering (-X pystats)\n"
	#endif
	"PYTHONTRACEMALLOC: trace Python memory allocations (-X tracemalloc)\n"
	"PYTHONUNBUFFERED: disable stdout/stderr buffering (-u)\n"
	"PYTHONUTF8 : control the UTF-8 mode (-X utf8)\n"
	"PYTHONVERBOSE : trace import statements (-v)\n"
	"PYTHONWARNDEFAULTENCODING: enable opt-in EncodingWarning for 'encoding=None'\n"
	" (-X warn_default_encoding)\n"
	"PYTHONWARNINGS : warning control (-W)\n"
	;

I did a search to figure out if these are intentionally missing, but wasn't able to find out.

Linked PRs

• gh-119574: Add some missing environment variables to '--help-env'. #120006