[X-Unix] So what is a dmg file?

[Dan Frakes]

Lotas Smartman <tiernanotoole at mac.com> wrote:
> actually a dmg file is something like a windows exe or a mac .app file.
> its a runnable file. it auto mounts an image, and sometimes
> uncompresses it too, and then you can use it. think of it as a self
> extracting zip file, without the extracting. or a virtual cdrom drive.

This isn't accurate. A dmg is simply a file format -- it contains no
executable code. In Jaguar and earlier, the mounting of a .dmg file is
handled by Disk Copy. In Panther, it's handled by
/System/Library/CoreServices/DiskImageMounter.

The disk images that appear to "mount automatically" are simply being
handled by a helper, just like a StuffIt or zip file. Those that appear to
"decompress and disappear" are actually just "Internet-enabled" images --
these images have a flag set that tells Disk Copy/DiskImageMounter to handle
them differently than other disk images files.


-- 
---------------------------
<http://www.danfrakes.com/>
---------------------------