Looking for QNX4 file reader


I have a Compact Flash card that is formatted QNX4. I’m looking for a utility that will allow files to be read on a Windows machine.

I’d be happy with a windows executable or C code that I could compile myself.

Anybody know where I can find such a beast?

Thank you.



I don’t know of any such software. When QNX moved from QNX 2 to QNX 4 the same issue came up with the QNX 2 file system. At that time I wrote some simple read only code that did was you describe. The QNX 4 file system isn’t well documented, however with some trial and error, it should not be a very difficult task. Under QNX 6 the file /usr/include/sys/fs_qnx4.h describes most of the structures you need to look at.

It’s also possible that someone has done something like this for Linux, so I’d check out that avenue first.

No guarantees, but you can give this experimental binary a try. It is for XP or win7 Professional only. Your security rights must be equivalent to administrator! The program requests a windows “drive” number you get by loading ‘disk management’ utility.


No “driver” is installed - the program reads raw disk structures in the manner suggested in previous reply by maschoen.

I’ve downloaded q4rw.exe, but it’s not clear how to use it.

Here’s part of its help message:

Usage: q4rw -dir | -tree [-vv]

    list files and directories recursively from
    an unmounted QNX4 filesystem

    hdNbr         - a zero-based drive number [\\.\PhysicalDrive<hdNbr>]
    ptblIndx      - a partition slot number [0..3]

\.\PhysicalDrive is something I’ve not seen before.

I’ve determined that from the command line one must double the backslashes. However trying hdNbr values (from 0 through 9) and ptbIndex values (from 0 to 3) just gave me 40 (10 * 4) copies of the help messages.

Any suggestions?

I’m guessing here. You have a windows system. It has disks. I think traditionally A: and B: are floppy drives.
Call them 1 and 2. That makes C: 3. You must have another disk in the system that has QNX on it. Probably D: 4 is a CD-ROM, although it could be QNX image. That means E: 5 might be the QNX disk. So

C> q4rw \5\ 0 -dir

to see the root directory?

Give it a try.

The program requests a windows “drive” number you get by loading ‘disk management’ utility.

Disk management assigns a “drive number” to each disk. That is the number you need.

Computer/Manage/Storage/Disk Management. The boot drive is usually 0 and contains C:

Within each drive are 4 primary partitions… 0…3. Specify the partition slot number after the drive number to q4rw.

I guess an example is required. Suppose you have you qnx4 filesystem on a usb harddrive and it is the first partition on the harddrive. Normally windows will assign the second drive as drive “1” - remember the bootdrive is “0”. So the command line to show the filenames on the disk would be

q4fs 1 0 -dir

The help does not actually say to include the text “\.\PhysicalDrive” … just , ‘1’ in this case. But to open a “raw” disk and read the partition table, the program will use the name “\.\PhysicalDrive1”.

You can use QNX 6 to view and read QNX 4 files.

I have a QNX4 CF disk liked you. I read files in this CF disk in a Windows machine as follow:

  • In Windows, install VMware
  • Install QNX 6 in VMware (recommend you should install ver 6.3.2 or later, it can mount USB devices automatically)
  • mount QNX4 CF disk in QNX6 with Card Reader (via USB cable)
  • use Photon File Manager in QNX6, you can view and read files in QNX4.

This is my solution.