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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, size_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.

       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(), the Base Definitions volume of IEEE Std 1003.1-2001, <fcntl.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 orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003				POSIX_FADVISE(3P)
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