usleep(3C)

NAME
     usleep - suspend execution for an interval

SYNOPSIS
     #include <unistd.h>

     int usleep (useconds_t seconds);

DESCRIPTION
     The usleep() function suspends the current thread from execution for the
     number of microseconds specified by the seconds argument.  Because of
     other activity, or because of the time spent in processing the call, the
     actual suspension time may be longer than the amount of time specified.

     The seconds argument must be less than 1,000,000.  If the value of
     seconds is 0, the call has no effect.

     The usleep() function uses the high resolution sleep function:
     nanosleep() to suspend execution of a thread.

DIAGNOSTICS
     Upon successful completion, a 0 value is returned.  Otherwise, -1 is
     returned and errno is set to indicate the error.  If the time interval
     specified is 1,000,000 or more microseconds, errno is set to EINVAL and
     -1 is returned from usleep().

SEE ALSO
     nanosleep(2).