Standard C Library (libc, -lc)

SYNOPSIS

     #include <unistd.h>

     int
     usleep(useconds_t microseconds);

DESCRIPTION

     The usleep() function suspends execution of the calling thread until
     either microseconds microseconds have elapsed or a signal is delivered to
     the thread and its action is to invoke a signal-catching function or to
     terminate the thread or process.  The actual time slept may be longer,
     due to system latencies and possible limitations in the timer resolution
     of the hardware.

     This function is implemented using nanosleep(2) by pausing for
     microseconds microseconds or until a signal occurs.  Consequently, in
     this implementation, sleeping has no effect on the state of process
     timers, and there is no special handling for SIGALRM.

RETURN VALUES

     The usleep() function returns the value 0 if successful; otherwise the
     value -1 is returned and the global variable errno is set to indicate the
     error.

ERRORS

     The usleep() function will fail if:

     [EINTR]            A signal was delivered to the process and its action
                        was to invoke a signal-catching function.

SEE ALSO

     nanosleep(2), sleep(3)

HISTORY

     The usleep() function appeared in 4.3BSD.

BSD                            February 13, 1998                           BSD