text: #include <stdio.h>
  #include <stdlib.h>
  #include <unistd.h>
  
  extern char **environ;
  
  static void fun1()
  {
  	printf("fun1\n");
  }
  
  static void fun2()
  {
  	printf("fun2\n");
  }
  
  static void fun3()
  {
  	printf("fun3\n");
  }
  
  static void test()
  {
  	printf("test()");
  	exit(0);
  }
  int main()
  {
  	for (int i = 0; environ[i] != NULL; i++)
  		puts(environ[i]);
  	atexit(fun1);
  	atexit(fun2);
  	atexit(fun3);
  	
  
  	test();
  	printf("main()");
  	exit(EXIT_SUCCESS);
  }
  