1POSIX_FADVISE(P)           POSIX Programmer's Manual          POSIX_FADVISE(P)
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NAME

6       posix_fadvise - file advisory information (ADVANCED REALTIME)
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SYNOPSIS

9       #include <fcntl.h>
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11       int posix_fadvise(int fd, off_t offset, size_t len, int advice);
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DESCRIPTION

15       The  posix_fadvise()  function  shall  advise the implementation on the
16       expected behavior of the application with respect to the  data  in  the
17       file  associated  with the open file descriptor, fd, starting at offset
18       and continuing for len bytes. The specified range  need  not  currently
19       exist  in the file. If len is zero, all data following offset is speci‐
20       fied. The implementation may use this information to optimize  handling
21       of  the  specified  data.  The  posix_fadvise()  function shall have no
22       effect on the semantics of other  operations  on  the  specified  data,
23       although it may affect the performance of other operations.
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25       The advice to be applied to the data is specified by the advice parame‐
26       ter and may be one of the following values:
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28       POSIX_FADV_NORMAL
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30              Specifies that the application has no  advice  to  give  on  its
31              behavior  with  respect to the specified data. It is the default
32              characteristic if no advice is given for an open file.
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34       POSIX_FADV_SEQUENTIAL
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36              Specifies that the application expects to access  the  specified
37              data sequentially from lower offsets to higher offsets.
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39       POSIX_FADV_RANDOM
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41              Specifies  that  the application expects to access the specified
42              data in a random order.
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44       POSIX_FADV_WILLNEED
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46              Specifies that the application expects to access  the  specified
47              data in the near future.
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49       POSIX_FADV_DONTNEED
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51              Specifies  that  the application expects that it will not access
52              the specified data in the near future.
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54       POSIX_FADV_NOREUSE
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56              Specifies that the application expects to access  the  specified
57              data once and then not reuse it thereafter.
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60       These values are defined in <fcntl.h>.
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RETURN VALUE

63       Upon  successful  completion, posix_fadvise() shall return zero; other‐
64       wise, an error number shall be returned to indicate the error.
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ERRORS

67       The posix_fadvise() function shall fail if:
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69       EBADF  The fd argument is not a valid file descriptor.
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71       EINVAL The value of advice is invalid.
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73       ESPIPE The fd argument is associated with a pipe or FIFO.
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76       The following sections are informative.
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EXAMPLES

79       None.
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APPLICATION USAGE

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

86       None.
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FUTURE DIRECTIONS

89       None.
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SEE ALSO

92       posix_madvise()  , the Base Definitions volume of IEEE Std 1003.1-2001,
93       <fcntl.h>
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96       Portions of this text are reprinted and reproduced in  electronic  form
97       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
98       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
99       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
100       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
101       event of any discrepancy between this version and the original IEEE and
102       The Open Group Standard, the original IEEE and The Open Group  Standard
103       is  the  referee document. The original Standard can be obtained online
104       at http://www.opengroup.org/unix/online.html .
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108IEEE/The Open Group                  2003                     POSIX_FADVISE(P)
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