| UALARM(3) | Library Functions Manual | UALARM(3) | 
ualarm —
#include <unistd.h>
useconds_t
  
  ualarm(useconds_t
    microseconds, useconds_t
    interval);
The ualarm() function waits a count of
    microseconds before asserting the terminating signal
    SIGALRM. System activity or time used in processing
    the call may cause a slight delay.
If the interval argument is non-zero, the
    SIGALRM signal will be sent to the process every
    interval microseconds after the timer expires (e.g.
    after microseconds microseconds have passed).
ualarm()
  returns the amount of time left on the clock. The maximum number of
  microseconds allowed is 2147483647. If there is an error
  setting the timer, ualarm() returns ((useconds_t) -1).
ualarm() function conforms to IEEE
  Std 1003.1-2001 (“POSIX.1”). However, the later
  IEEE Std 1003.1-2008 (“POSIX.1”)
  revision removed the function from the specification.
ualarm() function appeared in
  4.3BSD.
| May 2, 2011 | NetBSD 9.4 |