A little known capability of Mac OS X disk image system allows remote mounting of most disk images directly from "http://" URLs. However, this feature is not available in Disk Copy, so one must resort to the Terminal for mounting remote disk images. There are several reasons why one may want to mount a disk image remotely. Firstly, it allows selective downloads of just the interesting files from a disk image. This can be a real time-saver if you are on a modem trying to download just a few files from a huge disk image. Secondly, it avoids cluttering the hard drive with disk image files.
To mount a disk image remotely, enter the following command in Terminal:
% hdiutil mount "http://url.com/diskimage.dmg"For example:
% hdiutil mount "http://a1568.g.akamai.net/7/1568/NOTE: Shown on multiple lines for narrower reading; type on one line with no additional spaces in order to use the command. That command will mount the disk image containing the 45 MB large combo update to 10.1.5. Useful if you only need to retrieve a file or two using Pacifier. The feature is documented in the manual page for hdid, the command line program that is used by hdiutil to do the actual mounting.
1388/061-0008.20020604/download.info.apple.com/Apple_Support_Area/
Apple_Software_Updates/Mac_OS_X/downloads/061-0008.20020604/
MacOSXUpdateCombo.10.1.5.dmg.bin"
Mac OS X Hints
http://hints.macworld.com/article.php?story=2002071601585470