__attribute__((destructor[(priority)]))

where priority is an optional integer value denoting the priority. A destructor with a high integer value runs before a destructor with a low value. A destructor with a priority runs before a destructor without a priority.

Priority values up to and including 100 are reserved for internal use. If you use these values, the compiler gives a warning. Priority values above 100 are not reserved.

int my_destructor(void) __attribute__((destructor));

int my_destructor(void) /* This function is called after main() */
{                       /* completes or after exit() is called. */
   ...
   return 0;
}