Random Thoughts

Today I start a new series of blog posts directed at Mac users called OS X Tip. These will, as the name implies, offer tips that OS X users might find quite useful. I’ll compile a series of the handy tips and shortcuts you can use to make your OS X life more productive.

Today’s tip was something I found about just a few days ago. I had downloaded a .dmg file and needed to extract something from it inside Windows. Having my Windows 7 Boot Camp image running on VMware Fusion (more on this on a later blog post), I decided to mount the .dmg using VMware’s Choose Disk image option. Alas, I couldn’t: VMware doesn’t let you mount .dmg images! What to do now, what to do now?

I knew VMware could mount .iso files, so I searched around the Internet for a way to change .dmg files to .iso; gladly, I found what I was looking for and I’d love to share it.

I’ll demonstrate with a file in the Desktop, so, to make things easier for you, make sure you have your file in your own Desktop. Fire up Terminal.app and type

hdiutil convert ~/Desktop/filename.dmg -format UDTO -o ~/Desktop/filename.iso

Here’s a rundown of what we wrote:

• hdiutil  —  a command used to manipulate disk images (attach, verify, burn, etc)
• convert — what we want hdiutil to do; in this case it’s convert an image file
• ~/Desktop/filename.dmg — this is where our original image is located. The tilde is simply a time-saver that tells Terminal to look in the current user’s user folder (in my case, it would be /Users/ramcosca). Notice it ends with the file format .dmg!
• -format — this tells Terminal “Hey, convert the file I just mentioned to the file format I’m about to tell you!”
• UDTO — this is the specified format we will change it to. In this case, it’s a DVD/CD-R master for export.
• -o — telling Terminal “What comes after this command is the output file.”
• ~/Desktop/filename.iso — this is the location of the output file we wanted. Notice how it ends in .iso this time around.

Now, Terminal will work it’s magic and convert the file for you. It should look something like this:

Of course, this will vary from disk image to disk image. It depends on the content of the image, the size, the different parts for different OSs, etc.

Let me know in the comments if this tip helped you out. Also, if you have any questions you’d like me to answer, please do so in the comments!