gen/FreeBSD/sleep.3

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  28 .\"     @(#)sleep.3     8.1 (Berkeley) 6/4/93
  29 .\" $FreeBSD: src/lib/libc/gen/sleep.3,v 1.17 2007/01/09 00:27:55 imp Exp $
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  31 .Dd February 13, 1998
  32 .Dt SLEEP 3
  33 .Os
  34 .Sh NAME
  35 .Nm sleep
  36 .Nd suspend thread execution for an interval measured in seconds
  37 .Sh LIBRARY
  38 .Lb libc
  39 .Sh SYNOPSIS
  40 .In unistd.h
  41 .Ft unsigned int
  42 .Fn sleep "unsigned int seconds"
  43 .Sh DESCRIPTION
  44 The
  45 .Fn sleep
  46 function suspends execution of the calling thread until either
  47 .Fa seconds
  48 seconds 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 thread or 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 seconds
  57 seconds 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 If the
  63 .Fn sleep
  64 function returns because the requested time has elapsed, the value
  65 returned will be zero.
  66 If the
  67 .Fn sleep
  68 function returns due to the delivery of a signal, the value returned
  69 will be the unslept amount (the requested time minus the time actually
  70 slept) in seconds.
  71 .Sh SEE ALSO
  72 .Xr nanosleep 2 ,
  73 .Xr usleep 3
  74 .Sh STANDARDS
  75 The
  76 .Fn sleep
  77 function conforms to
  78 .St -p1003.1-90 .
  79 .Sh HISTORY
  80 A
  81 .Fn sleep
  82 function appeared in
  83 .At v7 .