gen/FreeBSD/usleep.3

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  28 .\"     @(#)usleep.3    8.1 (Berkeley) 6/4/93
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  31 .Dd February 13, 1998
  32 .Dt USLEEP 3
  33 .Os
  34 .Sh NAME
  35 .Nm usleep
  36 .Nd suspend thread execution for an interval measured in microseconds
  37 .Sh LIBRARY
  38 .Lb libc
  39 .Sh SYNOPSIS
  40 .In unistd.h
  41 .Ft int
  42 .Fn usleep "useconds_t microseconds"
  43 .Sh DESCRIPTION
  44 The
  45 .Fn usleep
  46 function suspends execution of the calling thread until either
  47 .Fa microseconds
  48 microseconds have elapsed or a signal is delivered to the thread and its
  49 action is to invoke a signal-catching function or to terminate the
  50 process.
  51 System activity or limitations may lengthen the sleep by an indeterminate amount.
  52 .Pp
  53 This function is implemented using
  54 .Xr nanosleep 2
  55 by pausing for
  56 .Fa microseconds
  57 microseconds or until a signal occurs.
  58 Consequently, in this implementation,
  59 sleeping has no effect on the state of process timers,
  60 and there is no special handling for SIGALRM.
  61 Also, this implementation does not put a limit on the value of
  62 .Fa microseconds
  63 (other than that limited by the size of the
  64 .Ft useconds_t
  65 type); some other platforms require it to be less than one million.
  66 .Sh NOTE
  67 The
  68 .Fn usleep
  69 function is obsolescent.
  70 Use
  71 .Xr nanosleep 2
  72 instead.
  73 .Sh RETURN VALUES
  74 .Rv -std usleep
  75 .Sh ERRORS
  76 The
  77 .Fn usleep
  78 function
  79 will fail if:
  80 .Bl -tag -width Er
  81 .It Bq Er EINTR
  82 A signal was delivered to the process and its
  83 action was to invoke a signal-catching function.
  84 .El
  85 .Sh SEE ALSO
  86 .Xr nanosleep 2 ,
  87 .Xr sleep 3
  88 .Sh HISTORY
  89 The
  90 .Fn usleep
  91 function appeared in
  92 .Bx 4.3 .