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   8 .Dd "Jul 20, 2014"
   9 .Dt USLEEP 3C
  10 .Os
  11 .Sh NAME
  12 .Nm usleep
  13 .Nd suspend execution for interval in microseconds
  14 .Sh SYNOPSIS
  15 .In unistd.h
  16 .Ft int
  17 .Fn usleep "useconds_t useconds"
  18 .Sh DESCRIPTION
  19 The
  20 .Fn usleep
  21 function suspends the caller from execution for the number
  22 of microseconds specified by the
  23 .Fa useconds
  24 argument. The actual suspension
  25 time might be less than requested because any caught signal will terminate
  26 .Fn usleep
  27 following execution of that signal's catching routine. The
  28 suspension time might be longer than requested by an arbitrary amount because
  29 of the scheduling of other activity in the system.
  30 .Lp
  31 If the value of
  32 .Fa useconds
  33 is 0, then the call has no effect.
  34 .Lp
  35 The use of the
  36 usleep
  37 function has no effect on the action or blockage
  38 of any signal. In a multithreaded process, only the invoking thread is
  39 suspended from execution.
  40 .Sh RETURN VALUES
  41 On completion,
  42 .Fn usleep
  43 returns 0. There are no error returns.
  44 .Sh ERRORS
  45 No errors are returned.
  46 .Sh USAGE
  47 The
  48 .Fn usleep
  49 function is included for its historical usage and is Obsolete.  The
  50 .Xr nanosleep 3C
  51 function is preferred over this function.
  52 .Sh INTERFACE STABILITY
  53 .Sy Obsolete Standard .
  54 .Sh MT-LEVEL
  55 .Sy Safe .
  56 .Sh SEE ALSO
  57 .Xr nanosleep 3C ,
  58 .Xr sleep 3C ,
  59 .Xr standards 5
  60 .Sh STANDARDS
  61 The
  62 .Fn usleep
  63 function was introduced in
  64 .Bx 4.3 ,
  65 and then standardized in
  66 .St -xpg4.2 .
  67 It was subsequently obsoleted in
  68 .St -p1003.1-2001 ,
  69 and removed from
  70 .St -p1003.1-2008 .