Apr 08

Struggles with creating Linux Live USB on Mac OSX

SO I've been trying to create a bootable live USB of some linux distro on the Mac and failed consistently. That is - until I found a magical solution!

I tried

  • dd-ing the .iso file onto the USB stick after unmounting, (and optionally partitioning to "Free Space" with Disk Utility)
  • Formatting to FAT32, then copying from .iso
  • Using UNetBootin for Mac OS X, that basically copies stuff and then adds its own bootloader "GUI"

Nothing worked. I kept getting "Missing Operating System" or just failures on boot...

Until I found a post by this guy Christofer, who published a very important piece of information that got me through the problem:
I needed to write the MBR to the USB after formatting to FAT32 because UNetBootin (or anything else) did not do that...

Basically the procedure is simple:
1. Format to FAT32 with Disk Utility

Make sure you select the Master Boot Record


2. Use fdisk to write the MBR to partition #1
Make sure you first unmount the partition using DiskUtil (or command line: diskutil umount /dev/disk1s1)

fdisk -e /dev/rdisk1
f 1

(it may complain a bit, but should work, just keep going)

3. get syslinux and upload the MBR binary
I had to use "/dev/disk1" instead of "/dev/rdisk1" to make it work.

dd conv=notrunc bs=440 count=1 if=mbr.bin of=/dev/disk1

You should see

1+0 records in
1+0 records out
440 bytes transferred in 0.000622 secs (707628 bytes/sec)

I've found the mbr.bin in the latest syslinux download under



4. Use UNetBootin as usual

That worked for me...