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.\"     @(#)sleep.3	8.1 (Berkeley) 6/4/93
.\"
.Dd May 17, 2010
.Dt NANOSLEEP 2
.Os
.Sh NAME
.Nm nanosleep
.Nd high resolution sleep
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In time.h
.Ft int
.Fn nanosleep "const struct timespec *rqtp" "struct timespec *rmtp"
.Sh DESCRIPTION
The
.Fn nanosleep
suspends execution of the calling process until either the number of
seconds and nanoseconds specified by
.Fa rqtp
have elapsed or a signal is delivered to the calling process and its
action is to invoke a signal catching function or to terminate the
process.
The suspension time may be longer than requested due to the
scheduling of other activity by the system.
The
.Em struct timespec
is described in
.Xr timespec 3 .
.Sh RETURN VALUES
If the
.Fn nanosleep
function returns because the requested time has elapsed, the value
returned will be zero.
.Pp
If the
.Fn nanosleep
function returns due to the delivery of a signal, the value returned
will be the \-1, and the global variable
.Va errno
will be set to indicate the interruption.
If
.Fa rmtp
is
.Pf non- Dv NULL ,
the timespec structure it references is updated to contain the
unslept amount (the request time minus the time actually slept).
.Sh ERRORS
If any of the following conditions occur, the
.Nm
function shall return \-1 and set
.Va errno
to the corresponding value.
.Bl -tag -width Er
.It Bq Er EFAULT
Either
.Fa rqtp
or
.Fa rmtp
points to memory that is not a valid part of the process
address space.
.It Bq Er EINTR
.Nm
was interrupted by the delivery of a signal.
.It Bq Er EINVAL
.Fa rqtp
specified a nanosecond value less than zero or greater than 1000 million.
.It Bq Er ENOSYS
.Nm
is not supported by this implementation.
.El
.Sh SEE ALSO
.Xr sleep 3 ,
.Xr timespec 3
.Sh STANDARDS
The
.Fn nanosleep
function conforms to
.St -p1003.1b-93 .