sleep.3

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)sleep.3	2.2	8/10/87
.TH sleep 3 
.SH Name
sleep \- suspend execution for interval
.SH Syntax
.nf
.B unsigned
.B sleep(seconds)
.B unsigned seconds;
.fi
.SH Description
.NXR "sleep subroutine (standard C)"
.NXR "process" "suspending"
The current process is suspended from execution for the number
of seconds specified by the argument.
The actual suspension time may be up to 1 second less than
that requested, because scheduled wakeups occur at fixed 1-second intervals,
and an arbitrary amount longer because of other activity
in the system.
.PP
The routine is implemented by setting an interval timer
and pausing until it occurs.
The previous state of this timer is saved and restored.
If the sleep time exceeds the time to the expiration of the
previous timer,
the process sleeps only until the signal would have occurred, and the
signal is sent 1 second later.
.SH Return Values
The value returned by 
.PN sleep
is the unslept amount(the requested time minus the time actually slept). This
return value may be non-zero in cases where the caller had an alarm set to go
off earlier than the end of the requested time, or where 
.PN sleep
was interrupted due to a caught signal(see ENVIRONMENT below).
.SH Environment
.PP
POSIX
.br
SYSTEM_FIVE
.br
When your program is compiled in POSIX or System V mode, the 
.PN sleep
will be terminated by any caught signal. The 
.PN sleep
function will return following execution of the signal's catching routine.
.SH See Also
setitimer(2), sigpause(2)