nanosleep

SYNOPSIS
       #include <time.h>

       int nanosleep(const struct timespec *rqtp, struct timespec *rmtp);


DESCRIPTION
       The nanosleep() function shall cause the current thread to be suspended
       from execution until either the time interval  specified  by  the  rqtp
       argument  has  elapsed  or a signal is delivered to the calling thread,
       and its action is to invoke a signal-catching function or to  terminate
       the  process.  The suspension time may be longer than requested because
       the argument value is rounded up to an integer multiple  of  the  sleep
       resolution  or  because of the scheduling of other activity by the sys-
       tem. But, except for the case of being interrupted  by  a  signal,  the
       suspension  time  shall not be less than the time specified by rqtp, as
       measured by the system clock CLOCK_REALTIME.

       The use of the nanosleep() function has no  effect  on  the  action  or
       blockage of any signal.

RETURN VALUE
       If  the  nanosleep()  function  returns  because the requested time has
       elapsed, its return value shall be zero.

       If the nanosleep() function returns because it has been interrupted  by
       a  signal,  it shall return a value of -1 and set errno to indicate the
       interruption. If the rmtp argument is non-NULL, the timespec  structure
       referenced  by it is updated to contain the amount of time remaining in
       the interval (the requested time minus the time actually slept). If the
       rmtp argument is NULL, the remaining time is not returned.

       If  nanosleep()  fails,  it shall return a value of -1 and set errno to
       indicate the error.

ERRORS
       The nanosleep() function shall fail if:

       EINTR  The nanosleep() function was interrupted by a signal.

       EINVAL The rqtp argument specified a nanosecond value less than zero or
              greater than or equal to 1000 million.


       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       signal  number.  This  volume  of  IEEE Std 1003.1-2001  requires  that
       nanosleep() be non-intrusive of the signals function.

       The nanosleep() function shall return a value of 0 on success and -1 on
       failure  or if interrupted. This latter case is different from sleep().
       This was done because the remaining time is returned  via  an  argument
       structure pointer, rmtp, instead of as the return value.

FUTURE DIRECTIONS
       None.

SEE ALSO
       sleep() , the Base Definitions volume of IEEE Std 1003.1-2001, <time.h>

COPYRIGHT
       Portions  of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE and
       The  Open Group Standard, the original IEEE and The Open Group Standard
       is the referee document. The original Standard can be  obtained  online
       at http://www.opengroup.org/unix/online.html .



IEEE/The Open Group                  2003                         NANOSLEEP(P)