Here's how I transfer files between my FreeDOS virtual machine and my
Linux desktop system.
![Files in a folder][1]
I run Linux as my primary operating system, and I boot FreeDOS in a virtual machine. Most of the time, I use QEMU as my PC emulator, but sometimes I'll run other experiments with GNOME Boxes (which uses QEMU as a back-end virtual machine) or with VirtualBox.
I like to play classic DOS games, and sometimes I'll bring up a favorite DOS application. I teach a Management Information Systems (MIS) class where I talk about the history of computing, and I'll sometimes record a demonstration using FreeDOS and a legacy DOS application, such as As-Easy-As (my favorite DOS spreadsheet—once released as "shareware" but now available[for free from TRIUS, Inc][2]).
But using FreeDOS this way means I need to transfer files between my FreeDOS virtual machine and my Linux desktop system. Let me show you how I do that.
### Accessing the image with guestmount
I used to access my virtual disk image by calculating the offset to the first DOS partition, then calling the Linux`mount`command with the right mixof options to match that offset. This was always error-prone and not very flexible. Fortunately, there's an easier way to do it. The`guestmount`program from the[libguestfs-tools][3]package lets you access or_mount_the virtual disk image from Linux. You can install `libguestfs-tools` using this command on Fedora:
```
`$ yum install libguestfs-tools libguestfs`
```
Using`guestmount`is not as easy as double-clicking the file from the GNOME file manager, but the command line isn't too difficult to use. The basic usage of`guestmount`is:
```
`$ guestmount -a image -m device mountpoint`
```
In this usage,_image_is the virtual disk image to use. On my system, I created my QEMU virtual disk image with the`qemu-img`command. The g`uestmount`program can read this disk image format, as well as the QCOW2 image format used by GNOME Boxes, or the VDI image format used in VirtualBox.
The_device_option indicates the partition on the virtual disk. Imagine using this virtual disk as a real hard drive. You would access the first partition as`/dev/sda1`, the second partition as`/dev/sda2`, and so on. That's the syntax for`guestmount`. By default, FreeDOS 1.3 RC4 creates one partition on an empty drive, so access that partition as`/dev/sda1`.
And_mountpoint_is the location to "mount" the DOS filesystem on your local Linux system. I'll usually create a temporary directory to work with. You only need the mount point while you're accessing the virtual disk.
Putting that all together, I use this set of commands to access my FreeDOS virtual disk image from Linux:
```
$ mkdir /tmp/freedos
$ guestmount -a freedos.img -m /dev/sda1 /tmp/freedos
```
After that, I can access my FreeDOS files via the`/tmp/freedos`directory, using normal tools on Linux. I might use`ls /tmp/freedos`at the command line, or open the`/tmp/freedos`mount point using the desktop file manager.
Using GNOME file manager to access the virtual disk
(Jim Hall, [CC-BY SA 4.0][5])
For example, to copy several C source files from my Linux`projects`directory into`C:\SRC`on the virtual disk image, so I can use the files under FreeDOS later, I can use the Linux`cp`command:
```
`$ cp /home/jhall/projects/*.c /tmp/freedos/SRC`
```
The files and directories on the virtual drive are technically_case insensitive_, so you can refer to them using uppercase or lowercase letters. However, I find it more natural to type DOS files and directories using all uppercase.
You should always_unmount_the virtual disk image before you use it again in your virtual machine. If you leave the image mounted while you run QEMU or VirtualBox, you risk messing up your files.
The companion command to`guestmount`is`guestunmount`, to unmount the disk image. Just give the mount point that you wish to unmount:
```
`$ guestunmount /tmp/freedos`
```
Note that this command is spelled slightly differently from the Linux`umount`system command.
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/files_documents_paper_folder.png?itok=eIJWac15 (Files in a folder)
