posix_fadvise.2 (2010 09)

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posix_fadvise(2) posix_fadvise(2)

NAME

posix_fadvise(), posix_fadvise64() - ﬁle advisory information

SYNOPSIS

#include <sys/fcntl.h>

int posix_fadvise(

int fd,

off_t offset,

off_t len,

int advice

);

int posix_fadvise64(

int fd,

off_t offset,

off_t len,

int advice

);

Parameters

fd The open ﬁle descriptor to which the fadvise operation applies.

offset The begining of the speciﬁed range as a positive, byte offset.

len The length of the speciﬁed range in bytes.

advice Speciﬁes advice to be applied to range.

DESCRIPTION

The

posix_fadvise()

function is used to advise the system about the expected behavior of the appli-

cation 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.

It should be noted that the effect of all hints is cumulative for a given ﬁle object. All hints will be

removed on processing the last close of the ﬁle object.

The

posix_fadvise64()

function may be used for large ﬁle access by a 32-bit application built with

_FILE_OFFSET_BITS

set to 64.

The advice parameter is used to convey the hint to be applied to the data 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 range of

data sequentially from the lower offsets to higher offsets.

POSIX_FADV_RANDOM Speciﬁes that the application will expect to access the speciﬁed

speciﬁed range of data in a random order.

POSIX_FADV_WILLNEED Speciﬁes that the application will expect to access the speciﬁed range

of data in the near future.

POSIX_FADV_DONTNEED Speciﬁes that the application will expect that it will not access the

speciﬁed range of data in the near future.

POSIX_FADV_NOREUSE Speciﬁes that the application will expect to access the speciﬁed range

of data once and then not reuse it thereafter.

These values will be deﬁned in

<sys/fcntl.h>.

RETURN VALUE

0 Successful completion.

-1 Failure. errno is set to indicate the error.

HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1

Summary of content (2 pages)

PAGE 1
posix_fadvise(2) posix_fadvise(2) NAME posix_fadvise(), posix_fadvise64() - file advisory information SYNOPSIS #include int posix_fadvise( int fd , off_t offset , off_t len , int advice ); int posix_fadvise64( int fd , off_t offset , off_t len , int advice ); Parameters fd The open file descriptor to which the fadvise operation applies. offset The begining of the specified range as a positive, byte offset. len The length of the specified range in bytes.
PAGE 2
posix_fadvise(2) posix_fadvise(2) ERRORS If the posix_fadvise() service fails, errno is set to one of the following values: [EBADF] The fd argument is not a valid file descriptor. [ESPIPE] The fd argument is associated with a pipe or FIFO. [ENOTTY] The posix_fadvise operation is not supported by the underlying file system. [EINVAL] The value of advice or one of the other input values has been found to be invalid. [ENOSYS] A designated hint is not supported by the underlying file object.