C - Environment variables access
================================

Public domain
********************************************************************************
    
    #include <stdio.h>
    #include <stdlib.h>
    
    int main ()
    {
      char *test = getenv ("TEST");
      if (test == NULL)
        printf ("TEST environment variable is not set because getenv returned NULL");
      else
        printf ("TEST environment variable is set and equal to: %s", test);
      return 0;
    }
    
********************************************************************************
### Output
    
    $ ./a.out 
    TEST environment variable is not set because getenv returned NULL
    
    $ TEST=1
    
    $ ./a.out 
    TEST environment variable is not set because getenv returned NULL
    
    $ echo $TEST 
    1
    
    $ export TEST
    
    $ ./a.out 
    TEST environment variable is set and equal to: 1
    
    $ unset TEST  
    
    $ ./a.out 
    TEST environment variable is not set because getenv returned NULL
    
    $ export TEST=""
    
    $ ./a.out 
    TEST environment variable is set and equal to: 
    
********************************************************************************
_BY: Pejman Moghadam_  
_TAG: c, getenv, environment_  
_DATE: 2011-06-02 16:59:40_