#include <sys/time.h>

int getitimer(int which, struct itimerval *curr_value);
int setitimer(int which, const struct itimerval *new_value,
                 struct itimerval *old_value);

setitimer()
   The function setitimer() arms or disarms the timer specified by  which,
   by setting the timer to the value specified by new_value.  If old_value
   is non-NULL, the buffer it points to is used  to  return  the  previous
   value  of  the  timer

RETURN VALUE
   On  success,  zero is returned.  On error, -1 is returned, and errno is set appropriately.