Making a Bootable USB Stick on an Apple Mac OS X from an ISO

This quick how-to will show you how to make a bootable USB stick from a downloaded ISO file using an Apple Mac OS X.

Note: this procedure requires an .img file that you will be required to create from the .iso file you download.

TIP: Drag and Drop a file from Finder to Terminal to ‘paste’ the full path without typing and risking type errors.

  1. Download the desired file
  2. Open the Terminal (in /Applications/Utilities/ or query Terminal in Spotlight)
  3. Convert the .iso file to .img using the convert option of hdiutil:
    hdiutil convert -format UDRW -o /path/to/target.img /path/to/source.iso)
  4. Note: OS X tends to put the .dmg ending on the output file automatically.
    Rename the file by typing:
    mv /path/to/target.img.dmg /path/to/target.img
  5. Run diskutil list to get the current list of devices
  6. Insert your flash media
  7. Run diskutil list again and determine the device node assigned to your flash media (e.g. /dev/disk2)
  8. Run diskutil unmountDisk /dev/diskN (replace N with the disk number from the last command; in the previous example, N would be 2)
  9. Execute sudo dd if=/path/to/downloaded.img of=/dev/rdiskN bs=1m (replace /path/to/downloaded.img with the path where the image file is located; for example, ./ubuntu.img or ./ubuntu.dmg).
    • Using /dev/rdisk instead of /dev/disk may be faster.
    • If you see the error dd: Invalid number '1m', you are using GNU dd. Use the same command but replace bs=1m with bs=1M.
    • If you see the error dd: /dev/diskN: Resource busy, make sure the disk is not in use. Start the ‘Disk Utility.app’ and unmount (don’t eject) the drive.
  10. Run diskutil eject /dev/diskN and remove your flash media when the command completes
  11. Now the USB stick is ready. Boot the device that you want from the USB stick.
This entry was posted in Mac by djlaube. Bookmark the permalink.

About djlaube

I have over 16+ years of experience helping small to enterprise businesses nationwide design and then implement enterprise storage, backup and recovery, disaster recovery and system virtualization solutions including private cloud, public cloud and hybrid cloud infrastructures. I hold numerous storage and virtualization certifications. I have supported 18-25 sales reps at any one time as a presales engineer, involved in all stages of the sales cycle. I have consistently been a top producer in all of my roles. I have personally delivered over 300+ complex enterprise solution implementations from multiple vendors (including VMware, EMC, Dell, Symantec and HP). I am an expert in solution design and architecture and have designed over 250+ complex solutions for customers of all sizes (SMB to Fortune 100).

3 thoughts on “Making a Bootable USB Stick on an Apple Mac OS X from an ISO

  1. No need for that

    ——

    Run diskutil list to get the current list of devices

    Insert your flash media

    Run diskutil list again and determine the device node assigned to your flash media (e.g. /dev/disk2)

    —-

    Go to disk util with the media mounted right click on the left hand list
    and select “information”. Check the “disk identifier” entry.

    Great guide.

  2. It just doesn’t work wasted another 2 hours. Amazed that there is not a simple solution to make a bootable USB, been through 5 of these schemes and they fail. Comments support the idea that they do not work. I assume the lack of comments here is due to the author deleting any post that is not glowing

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