> Windows does a similar thing, except it uses \\?\PhysicalDisk0 as the
> name. And this "file" exists if and only if disk 0 is actually plugged in.

Yes, I use the \\?\{<drive_guid>} syntax to make sure my backups always 
get written to the correct drive (with several hard drives and USB 
storage devices connected I am never sure if the drive letters will be 
repeatable).

> Linux now uses a system called UDev. Instead of the OS installer running
> mknod to generate device nodes for every device that could ever be
> plugged in, the actual /dev folder is empty. The UDev software then
> dynamically creates the appropriate device node when I device is plugged
> in, and deletes it when the device is unplugged again. In this way, only
> nodes for devices that actually exist show up.
>
> This is all very useful. But file redirection is such that if you
> redirect to an existing file, it is overwritten (the behaviour we want
> for our disk image), but if the file does /not/ exist, it gets created.
> And /dev isn't special; it's just a normal folder. The name /dev/sda is
> also not special; it's just a regular file.

I only have one annoyance left with my linux setup, I have the external 
USB drive connected most of the time to it and it always appears as 
/media/EXTERNAL (EXTERNAL is the drive name). However, if I boot it up 
*without* the drive connected once, it will never appear again unless I 
manually create the folder /media/EXTERNAL and reboot. I don't know 
enough about what goes on behind the scenes to prevent this happening.

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