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.TH FDATASYNC 3C "Feb 5, 2008"
.SH NAME
fdatasync \- synchronize a file's data
.SH SYNOPSIS
.LP
.nf
#include <unistd.h>

\fBint\fR \fBfdatasync\fR(\fBint\fR \fIfildes\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBfdatasync()\fR function forces all currently queued I/O operations
associated with the file indicated by file descriptor \fIfildes\fR to the
synchronized I/O completion state.
.sp
.LP
The functionality is as described for \fBfsync\fR(3C) (with the symbol
\fB_XOPEN_REALTIME\fR defined), with the exception that all I/O operations are
completed as defined for synchronised I/O data integrity completion.
.SH RETURN VALUES
.sp
.LP
If successful, the \fBfdatasync()\fR function returns \fB0\fR. Otherwise, the
function returns \fB\(mi1\fR and sets \fBerrno\fR to indicate the error. If the
\fBfdatasync()\fR function fails, outstanding I/O operations are not guaranteed
to have been completed.
.SH ERRORS
.sp
.LP
The  \fBfdatasync()\fR function will fail if:
.sp
.ne 2
.na
\fB\fBEBADF\fR\fR
.ad
.RS 10n
The \fIfildes\fR argument is not a valid file descriptor open for writing.
.RE

.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
The system does not support synchronized I/O for this file.
.RE

.sp
.ne 2
.na
\fB\fBENOSYS\fR\fR
.ad
.RS 10n
The function \fBfdatasync()\fR is not supported by the system.
.RE

.sp
.LP
In the event that any of the queued I/O operations fail, \fBfdatasync()\fR
returns the error conditions defined for \fBread\fR(2) and \fBwrite\fR(2).
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Committed
_
MT-Level	Async-Signal-Safe
_
Standard	See \fBstandards\fR(5).
.TE

.SH SEE ALSO
.sp
.LP
\fBfcntl\fR(2), \fBopen\fR(2), \fBread\fR(2), \fBwrite\fR(2), \fBfsync\fR(3C),
\fBaio_fsync\fR(3C), \fBfcntl.h\fR(3HEAD), \fBattributes\fR(5),
\fBstandards\fR(5)