Wednesday, August 27, 2008

Make a Bootable USB from a DMG

Here's the simplest process I have seen...

  • Mount a bootable DMG image so it appears in /Volumes (eg. /Volumes/SomeAppDisk)

  • Mount a USB Key you don't mind erasing (eg. /Volumes/USBToBeWiped ) (should happen just by sticking it in the machine)

  • From a terminal type
    sudo asr --restore --source /Volumes/SomeAppDisk --target /Volumes/USBToBeWiped --erase

  • wait ....10....20....30....40....50....60....70....80....90....100

Note: --erase will cause the usb key to be wiped AND is what 'bless'es the device so it becomes bootable.

There you go..


MacPhreak said...

You need to mention or people need to know a few things. You cannot use the Install MAc OSX from the install disc or use the startup disc. The only way it will boot is using the "Option" on startup. Other than that it works great. In fact i just used it on my External Firewire drive

David said...

Does this work with .iso files as well?

Nigel said...

Sorry David, not to my knowledge. No.

dkliman said...

@david I did use disk utility to save an iso file as a DMG, and the rest worked fine.

Here's the instructions:

Storage Toronto said...

Thanks, this is probably the simplest method i have seen so far. I was a little confused at first before i realized that i had to have the USB drive mounted for this to work.

Nigel said...

A good technique for iso's is mentioned here


dd if=/path/to/file.iso of=/dev/sdb

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