getenv(3)

NAME
     getenv - value for environment name

SYNOPSIS
     #include <stdlib.h>

     char *getenv(const char *name)

DESCRIPTION
     Getenv searches the environment list (see environ(7)) for a string of the
     form  name=value  and  returns  a  pointer  to the string value if such a
     string is present, otherwise getenv returns the null pointer.

SEE ALSO
     environ(7), execve(2).