getenv

getenv, getenv_s

Defined in header <stdlib.h>
char *getenv( const char *name );
(1)
errno_t getenv_s( size_t *restrict len, char *restrict value,
                  rsize_t valuesz, const char *restrict name );
(2) (since C11)
1) Searches for an environmental variable with name name in the host-specified environment list and returns a pointer to the string that is associated with the matched environment variable. The set of environmental variables and methods of altering it are implementation-defined. <