Unmounting a drive

After mounting drive 4, is there a command to unmount? Thx

I know there is “Umount”. But I don’t see it in the cmds directory.

Hmmmm, what would unmounting it mean? If you mean that the drive is no longer accessable, this would not be hard to do by mounting something else in it’s place. A simple way to do this might be to mount it as a floppy.

mount disk 4 d=1

I don’t know if that would actually work, but you could try it.

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We want to make it inaccessible after it is used to backup drive 3. So the script would mount 4, do the backup, then unmount. Don’t understand why there is no UMOUNT.

A good question. Consider what happens in Posix (QNX4, 6 and 7). A driver that finds a drive creates an entry in /dev. Then the user can mount the device into the file system. Unmounting just removes the access to the drive but the device still exists.

QNX 2 was much more rudamentary. It was written around the same time that MSDOS appeared. Drivers were not independent processes the way they are in future QNX releases. Instead they were more like a shared library that only the fsys process could use. When a driver was started, any drive found was given a number, e.g. 4. Now mounting was required. You could immediately access the drive as 4:/ if the drive had a qnx 2 files system on it. You could mount another driver in its place by using the same number. This actually caused the system to lose a chunk of memory that could only be restored with a reboot. This is also a way to unmount the drive, although it is fairly awkward.

If there was an important reason to provide a nice clean “unmount” function that would make the drive unavailable, I would go about it as follows. I would take an existing driver code and evicerate it, returning an error for both reads and writes. This driver would take up very little ram as there would be no functionality in it. I’m probably the only person on earth who still has both the equipment, knowledge and any inclindation to do such a thing.

That worked, Thank you M

Just curious, what worked? Did you create a code empty driver that returned an error so you could mount it in place or something else?

Mount disk 4 d=1 … .