gen/sleep.3

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  32 .\"     @(#)sleep.3     8.1 (Berkeley) 6/4/93
  33 .\" $FreeBSD: src/lib/libc/gen/sleep.3,v 1.16 2004/07/02 23:52:10 ru Exp $
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  35 .Dd February 13, 1998
  36 .Dt SLEEP 3
  37 .Os
  38 .Sh NAME
  39 .Nm sleep
  40 .Nd suspend thread execution for an interval measured in seconds
  41 .Sh LIBRARY
  42 .Lb libc
  43 .Sh SYNOPSIS
  44 .In unistd.h
  45 .Ft unsigned int
  46 .Fn sleep "unsigned int seconds"
  47 .Sh DESCRIPTION
  48 The
  49 .Fn sleep
  50 function suspends execution of the calling thread until either
  51 .Fa seconds
  52 seconds have elapsed or a signal is delivered to the thread and its
  53 action is to invoke a signal-catching function or to terminate the
  54 thread or process.
  55 System activity may lengthen the sleep by an indeterminate amount.
  56 .Pp
  57 This function is implemented using
  58 .Xr nanosleep 2
  59 by pausing for
  60 .Fa seconds
  61 seconds or until a signal occurs.
  62 Consequently, in this implementation,
  63 sleeping has no effect on the state of process timers,
  64 and there is no special handling for SIGALRM.
  65 .Sh RETURN VALUES
  66 If the
  67 .Fn sleep
  68 function returns because the requested time has elapsed, the value
  69 returned will be zero.
  70 If the
  71 .Fn sleep
  72 function returns due to the delivery of a signal, the value returned
  73 will be the unslept amount (the requested time minus the time actually
  74 slept) in seconds.
  75 .Sh SEE ALSO
  76 .Xr nanosleep 2 ,
  77 .Xr usleep 3
  78 .Sh STANDARDS
  79 The
  80 .Fn sleep
  81 function conforms to
  82 .St -p1003.1-90 .
  83 .Sh HISTORY
  84 A
  85 .Fn sleep
  86 function appeared in
  87 .At v7 .