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USLEEP(3)		    Library Functions Manual		     USLEEP(3)

NAME
       usleep  --  suspend  thread  execution  for an interval measured	in mi-
       croseconds

LIBRARY
       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	process.  System activity may lengthen the sleep by an
       indeterminate amount.

       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	calling	thread and its
			  action was to	invoke a signal-catching function.

SEE ALSO
       nanosleep(2), sleep(3)

HISTORY
       The usleep() function appeared in 4.3BSD.

FreeBSD	14.3		       February	11, 2021		     USLEEP(3)

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<https://man.freebsd.org/cgi/man.cgi?query=usleep&sektion=3&manpath=FreeBSD+14.3-RELEASE+and+Ports>

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