PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

NANOSLEEP(3P)             POSIX Programmer's Manual            NANOSLEEP(3P)

PROLOG         top

       This manual page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior), or
       the interface may not be implemented on Linux.

NAME         top

       nanosleep — high resolution sleep

SYNOPSIS         top

       #include <time.h>

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

DESCRIPTION         top

       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 system. 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         top

       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). The rqtp and rmtp arguments may point to the same object. 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         top

       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         top

       None.

APPLICATION USAGE         top

       None.

RATIONALE         top

       It is common to suspend execution of a thread for an interval in
       order to poll the status of a non-interrupting function. A large
       number of actual needs can be met with a simple extension to sleep()
       that provides finer resolution.

       In the POSIX.1‐1990 standard and SVR4, it is possible to implement
       such a routine, but the frequency of wakeup is limited by the
       resolution of the alarm() and sleep() functions. In 4.3 BSD, it is
       possible to write such a routine using no static storage and
       reserving no system facilities. Although it is possible to write a
       function with similar functionality to sleep() using the remainder of
       the timer_*() functions, such a function requires the use of signals
       and the reservation of some signal number. This volume of
       POSIX.1‐2008 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         top

       None.

SEE ALSO         top

       clock_nanosleep(3p), sleep(3p)

       The Base Definitions volume of POSIX.1‐2008, time.h(0p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) 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.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the
       source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                 2013                       NANOSLEEP(3P)

Pages that refer to this page: time.h(0p)clock_getres(3p)clock_nanosleep(3p)sleep(3p)