Make A Bootable USB/SD Card On Mac OS X

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Many of us want to dual boot our PC or make a bootable disk, usb or sd card for performing a fresh installation of OS on our PC. But how to make a bootable usb or sd card. Well on Mac, it can be done via an application such as UNetbootin (my personal favourite) or using Terminal. I prefer the Terminal method. But I would advise beginners to use UNetbootin.

This tutorial will focus on Terminal. Just make sure you follow the steps properly or else the USB or SD Card can be malfunctioned through this method. So write down all the commands meticulously.


  1. Connect a USB or SD Card.
  2. Open Disk Utility, either through Spotlight or Launchpad or Finder.
  3. Select the USB or SD Card in left sidebar and click on Erase.
  4. Now select the format as MS DOS FAT from drop down menu. Give a name to your USB/SD Card. Naming is optional. Then click on the Erase button below.
  5. Format USB/SD Card on Mac OS X

    Format USB/SD Card on Mac OS X

  6. Next step is to open Terminal. Again use Finder or Spotlight or Launchpad to open it.
  7. Go to the location where your image file is located. Like lets say desktop for example. So I will type in cd Desktop
  8. Now we will find all the disk drives connected to the Mac. So type sudo diskutil list
  9. It is important that you find which is the USB or SD Card. This can be done by observing the size of the USB or SD Card.
  10. List of Drives Connected to Mac

    List of Drives Connected to Mac

  11. Another important thing to note down is the Identifier. This will be required to unmount the drive as well as make it bootable. In my case the identifier is /dev/disk2. Also note down the sub identifiers that is the identifiers of partitions. I have only one partition, hence the sub identifier is /dev/disk2s1. Make sure you have only 1 partition or else you can find yourself in some serious trouble with the USB/SD Card.
  12. To unmount the main drive we will type sudo umount disk2 or sudo umount /dev/disk2. Instead of disk2, type your identifier.
  13. Now its time to unmount the sub partitions. For this we will type sudo diskutil umount disk2s1 or sudo diskutil umount /dev/disk2s1. Instead of disk2s1, type your identifier.
  14. Unmounting Drives On Mac

    Unmounting Drives On Mac

  15. We are through with 90% of the procedure. Its time to make the USB or SD Card bootable. For this we need to use the dd command. Once again, make sure you type in the command precisely or else you will find your USB or SD Card malfunctioned.

sudo dd bs=4m of=/dev/disk2

bs specifies the block size. if specifies the file to be placed in the drive. of specifies the drive where the file has to be placed.

The DD Command

The DD Command

Once this command is typed, press enter and wait for few minutes. The only indication that the process is still going on is the scintillating LED on the USB. This can take around 15-20 minutes. So be patient.

That’s it. Once the process completes, eject the USB/SD Card and you can use it to boot an OS. To boot on Mac make sure you hold and press the Option key when Mac restarts. Enjoy.


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