This is the standard C library getenv() function from stdlib.h. It gets the value of a specified environment variable.
char *getenv(const char *name);
The default implementation returns NULL, indicating that no environment information is available.
If you re-implement getenv(), ARM recommends that you re-implement it in such a way that it searches some form of environment list for the input string, name . The set of environment names and the method for altering the environment list are implementation-defined. getenv() does not depend on any other function, and no other function depends on getenv().
A function closely associated with getenv() is _getenv_init(). _getenv_init() is called during startup if it is defined, to enable a user re-implementation of getenv() to initialize itself.
The return value is a pointer to a string associated with the matched list member. The array pointed to must not be modified by the program, but might be overwritten by a subsequent call to getenv().