gen/FreeBSD/usleep.3

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  28 .\"     @(#)usleep.3    8.1 (Berkeley) 6/4/93
  29 .\" $FreeBSD: src/lib/libc/gen/usleep.3,v 1.19 2007/01/09 00:27:56 imp Exp $
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  31 .Dd February 13, 1998
  32 .Dt USLEEP 3
  33 .Os
  34 .Sh NAME
  35 .Nm usleep
  36 .Nd suspend process 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 process until either
  47 .Fa microseconds
  48 microseconds have elapsed or a signal is delivered to the process and its
  49 action is to invoke a signal-catching function or to terminate the
  50 process.
  51 System activity 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 .Sh RETURN VALUES
  62 .Rv -std usleep
  63 .Sh ERRORS
  64 The
  65 .Fn usleep
  66 function
  67 will fail if:
  68 .Bl -tag -width Er
  69 .It Bq Er EINTR
  70 A signal was delivered to the process and its
  71 action was to invoke a signal-catching function.
  72 .El
  73 .Sh SEE ALSO
  74 .Xr nanosleep 2 ,
  75 .Xr sleep 3
  76 .Sh HISTORY
  77 The
  78 .Fn usleep
  79 function appeared in
  80 .Bx 4.3 .