Flushes data all the way to the disk.

    Format

      #include  <unistd.h>

      int fsync  (int fd);

1 - Argument

 fd

    A file descriptor corresponding to an open file.

2 - Description

    The fsync function behaves much like the fflush function. The
    primary difference between the two is that fsync flushes data
    all the way to the disk while fflush flushes data only as far as
    the underlying RMS buffers. Also, with fflush, you can flush all
    buffers at once; with fsync you cannot.

3 - Return Values

    0                  Indicates successful completion.
    -1                 Indicates an error.