पायथन में एन्वायरनमेंट वेरिएबल्स का उपयोग: os.environ, os.environb और क्रॉस-प्लेटफ़ॉर्म विचार

import os

# Distinguish absent from empty
value = os.environ.get("APP_MODE")
if value is None:
    print("variable not set")
else:
    print("value:", repr(value))

import os

os.environ["APP_MODE"] = "production"  # calls setenv
os.environ.pop("APP_MODE", None)       # calls unsetenv if present

import os

if os.supports_bytes_environ:
    os.environb[b"RAW_KEY"] = b"\xff\xfe"
    print(os.environ["RAW_KEY"])  # decoded via fsencode/fsdecode

import os, sys

print("filesystem encoding:", sys.getfilesystemencoding())
print("utf8 mode:", sys.flags.utf8_mode)

# Raw bytes access (Unix only)
if os.supports_bytes_environ:
    raw = os.getenvb(b"LANG")
    print("LANG bytes:", raw)

import os

# After external modification of the process environment:
os.reload_environ()  # Python 3.14+
print(os.environ.get("EXTERNALLY_SET_VAR"))

import os

try:
    os.environ["BAD_KEY"] = "value\ud800"  # lone surrogate
except UnicodeEncodeError as e:
    print("encoding error:", e)

import os

print("os.name:", os.name)
print("supports_bytes_environ:", os.supports_bytes_environ)
print("exec paths:", os.get_exec_path())

import os

child_env = dict(os.environ)
child_env["APP_MODE"] = "production"
# spawnvpe replaces the child environment entirely
status = os.spawnvpe(os.P_WAIT, "cp", ["cp", "index.html", "/dev/null"], child_env)
print("exit status:", status)