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 correspond-
       ing 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  charac-
	      teristic 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 Technol-
       ogy -- 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							 POSIX_FADVISE(3P)