posix_fadvise(3p) — Linux manual page

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

PROLOG

       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

       posix_fadvise — file advisory information (ADVANCED REALTIME)

SYNOPSIS

       #include <fcntl.h>

       int posix_fadvise(int fd, off_t offset, off_t len, int advice);

DESCRIPTION

       The posix_fadvise() function shall advise the implementation on
       the expected behavior of the application with respect to the data
       in the file associated with the open file descriptor, fd,
       starting at offset and continuing for len bytes. The specified
       range need not currently exist in the file. If len is zero, all
       data following offset is specified. The implementation may use
       this information to optimize handling of the specified data. The
       posix_fadvise() function shall have no effect on the semantics of
       other operations on the specified data, although it may affect
       the performance of other operations.

       The advice to be applied to the data is specified by the advice
       parameter and may be one of the following values:

       POSIX_FADV_NORMAL
             Specifies that the application has no advice to give on its
             behavior with respect to the specified data. It is the
             default characteristic if no advice is given for an open
             file.

       POSIX_FADV_SEQUENTIAL
             Specifies that the application expects to access the
             specified data sequentially from lower offsets to higher
             offsets.

       POSIX_FADV_RANDOM
             Specifies that the application expects to access the
             specified data in a random order.

       POSIX_FADV_WILLNEED
             Specifies that the application expects to access the
             specified data in the near future.

       POSIX_FADV_DONTNEED
             Specifies that the application expects that it will not
             access the specified data in the near future.

       POSIX_FADV_NOREUSE
             Specifies that the application expects to access the
             specified data once and then not reuse it thereafter.

       These values are defined in <fcntl.h>.

RETURN VALUE

       Upon successful completion, posix_fadvise() shall return zero;
       otherwise, an error number shall be returned to indicate the
       error.

ERRORS

       The posix_fadvise() function shall fail if:

       EBADF  The fd argument is not a valid file descriptor.

       EINVAL The value of advice is invalid, or the value of len is
              less than zero.

       ESPIPE The fd argument is associated with a pipe or FIFO.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       The posix_fadvise() function is part of the Advisory Information
       option and need not be provided on all implementations.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       posix_madvise(3p)

       The Base Definitions volume of POSIX.1‐2017, fcntl.h(0p)

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 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 .

       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               2017                 POSIX_FADVISE(3P)

Pages that refer to this page: fcntl.h(0p), posix_madvise(3p)

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