The Open Group Base Specifications Issue 7, 2018 edition
IEEE Std 1003.1-2017 (Revision of IEEE Std 1003.1-2008)
Copyright © 2001-2018 IEEE and The Open Group

NAME

fdatasync - synchronize the data of a file (REALTIME)

SYNOPSIS

[SIO] [Option Start] #include <unistd.h>

int fdatasync(int
fildes); [Option End]

DESCRIPTION

The fdatasync() function shall force all currently queued I/O operations associated with the file indicated by file descriptor fildes to the synchronized I/O completion state.

The functionality shall be equivalent to fsync() with the symbol _POSIX_SYNCHRONIZED_IO defined, with the exception that all I/O operations shall be completed as defined for synchronized I/O data integrity completion.

RETURN VALUE

If successful, the fdatasync() function shall return the value 0; otherwise, the function shall return the value -1 and set errno to indicate the error. If the fdatasync() function fails, outstanding I/O operations are not guaranteed to have been completed.

ERRORS

The fdatasync() function shall fail if:

[EBADF]
The fildes argument is not a valid file descriptor.
[EINVAL]
This implementation does not support synchronized I/O for this file.

In the event that any of the queued I/O operations fail, fdatasync() shall return the error conditions defined for read() and write().


The following sections are informative.

EXAMPLES

None.

APPLICATION USAGE

Note that even if the file descriptor is not open for writing, if there are any pending write requests on the underlying file, then that I/O will be completed prior to the return of fdatasync().

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

aio_fsync, fcntl, fsync, open, read, write

XBD <unistd.h>

CHANGE HISTORY

First released in Issue 5. Included for alignment with the POSIX Realtime Extension.

Issue 6

The [ENOSYS] error condition has been removed as stubs need not be provided if an implementation does not support the Synchronized Input and Output option.

The fdatasync() function is marked as part of the Synchronized Input and Output option.

Issue 7

POSIX.1-2008, Technical Corrigendum 2, XSH/TC2-2008/0110 [501] is applied.

End of informative text.

 

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