getenv, setenv, putenv, unsetenv test

#include <stdio.h>
#define __USE_XOPEN
#define __USE_XOPEN2K
#include <stdlib.h>


int
main ()
{

  printf ("HOME : %s\n", getenv ("HOME"));


  printf ("PATH : %s\n", getenv ("PATH"));


  const char *str = getenv ("SOME_VARIABLE");

  printf ("SOME_VARIABLE : %s\n", str != NULL ? str : "NULL");

  putenv ("SOME_VARIABLE=10");

  printf ("SOME_VARIABLE : %s\n", getenv ("SOME_VARIABLE"));

  unsetenv ("SOME_VARIABLE");



  setenv ("SOME_VARIABLE", "20", 1);

  printf ("SOME_VARIABLE : %s\n", getenv ("SOME_VARIABLE"));

  unsetenv ("SOME_VARIABLE");

  return (0);
}