Flush out-of-date disk buffers
fdflush is a band-aid for floppy (or other) drives with bad disk-change sensing. fdflush makes the system believe the disk-change switch has been triggered forcing the system to discard the buffered data.
If you have one of these slightly-broken disk drives, you'll have to run fdflush every time you change a disk.
fdflush is useful for computers which might be sleeping when you change floppies or other removable media.
The command "floppycontrol -f" does the same thing, but the fdutils package is significantly larger; it only uses the floppy-specific flush ioctl.
The command "blockdev --flushbufs" only uses the generic flush ioctl.