1POSIX_FADVISE(3P)          POSIX Programmer's Manual         POSIX_FADVISE(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

13       posix_fadvise — file advisory information (ADVANCED REALTIME)
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SYNOPSIS

16       #include <fcntl.h>
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18       int posix_fadvise(int fd, off_t offset, off_t len, int advice);
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DESCRIPTION

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

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

66       The posix_fadvise() function shall fail if:
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68       EBADF  The fd argument is not a valid file descriptor.
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70       EINVAL The value of advice is invalid, or the value of len is less than
71              zero.
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73       ESPIPE The fd argument is associated with a pipe or FIFO.
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75       The following sections are informative.
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EXAMPLES

78       None.
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APPLICATION USAGE

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

85       None.
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FUTURE DIRECTIONS

88       None.
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SEE ALSO

91       posix_madvise()
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93       The Base Definitions volume of POSIX.1‐2008, <fcntl.h>
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96       Portions  of  this text are reprinted and reproduced in electronic form
97       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
98       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
99       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
100       cal  and  Electronics  Engineers,  Inc  and  The  Open Group.  (This is
101       POSIX.1-2008 with the 2013 Technical Corrigendum  1  applied.)  In  the
102       event of any discrepancy between this version and the original IEEE and
103       The Open Group Standard, the original IEEE and The Open Group  Standard
104       is  the  referee document. The original Standard can be obtained online
105       at http://www.unix.org/online.html .
106
107       Any typographical or formatting errors that appear  in  this  page  are
108       most likely to have been introduced during the conversion of the source
109       files to man page format. To report such errors,  see  https://www.ker
110       nel.org/doc/man-pages/reporting_bugs.html .
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114IEEE/The Open Group                  2013                    POSIX_FADVISE(3P)
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