bionic (3) posix_fadvise.3posix.gz

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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()

       The Base Definitions volume of POSIX.1‐2008, <fcntl.h>


       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 .