RefreshNotes: C Communication with the environment Functions

Communication with the environment Functions:

abort	_Noreturn void abort(void);
exit	_Noreturn void exit(int status);
quick_exit(C11)	_Noreturn void quick_exit(int status);
_Exit(C99)	_Noreturn void _Exit(int status);
atexit	int atexit(void (*func)(void));
at_quick_exit(C11)	int at_quick_exit(void (*func)(void));
system	int system(const char *string);
getenv	char getenv( const* char *name );
getenv_s(C11)	errno_t getenv_s( size_t *restrict len, char *restrict value, rsize_t valuesz, const char *restrict name );