I'd like to follow up on my recent Create Bootable USB from ISO post for MacOS: seems I have missed an important point. This post shows you how to burn ISO to USB in MacOS.
Specifically, I tested my procedure using Macbook and VirtualBox/Parallels VMs but the same bootable USB stick would for some reason not boot on a standard physical PC.
ISO to USB
After a bit more research, I realise now that the following step missing: unlike other operating systems, in MacOS you must convert an ISO image into a different image format, UDRW. If you don't, your resulting USB stick will not boot (but still have all the valid files).
Convert ISO into bootable image
We convert ISO image into UDRW format using the excellent hdutil command. I only need cd /Volumes/Stuff/dist command because that's where I keep my ISO images.
In this example, I'm converting a CentOS 7 bootable DVD ISO:
greys@maverick:/ $ cd /Volumes/Stuff/dist $ ls -al CentOS* -rw-r--r--@ 1 greys staff 4521459712 13 Apr 2018 CentOS-7-x86_64-DVD-1708.iso $ hdiutil convert -format UDRW -o centos CentOS-7-x86_64-DVD-1708.iso Reading Master Boot Record (MBR : 0)… Reading CentOS 7 x86_64 (Apple_ISO : 1)… Reading (Type EF : 2)… Reading CentOS 7 x86_64 (Apple_ISO : 3… ............................................................. Elapsed Time: 10m 15.681s Speed: 7.0Mbytes/sec Savings: 0.0% created: /Volume/Stuff/dist/centos.dmg $ ls -al centos.dmg -rw-r--r-- 1 greys staff 4520542208 2 Jan 17:54 centos.dmg
Burn image to make bootable USB stick in MacOS
As in the original bootable USB from ISO procedure for Mac, we'll use dd command:
As you remember, dd command needs 3 parameters for our scenario:
- if – specifying the image we'd like to burn
- of – specifying the destination device, a USB disk /dev/disk9 in our case
- bs – a large enough block size, 1m (means 1 MegaByte)
here's how we use dd to burn centos.dmg:
$ sudo dd if=./centos.dmg of=/dev/disk9 bs=1m 4311+1 records in 4311+1 records out 4520542208 bytes transferred in 1486.155206 secs (3041770 bytes/sec)
That's it! The USB stick is ready, you can use it with a VM or physical desktop – it will definitely boot now!
pS: I'll update the original ISO to bootable USB on Mac page as well.