How to burn an ISO to a USB stick

Here is how to write a ISO file to a USB stick so you can boot from it.

  1. Run the diskutil command to get a list of disk.
    Be very careful to make sure you select the correct disk. Here its easy its the only one that is 8.0GB in size.
    NOTE: I have removed the others disks from the list to make the post shorter.
malcolms-macbook-pro:~ malcolm$ diskutil list
/dev/disk3 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *8.0 GB     disk3
   1:               Windows_NTFS Untitled                8.0 GB     disk3s1

2. Next, you need to unmount the disk

malcolms-macbook-pro:~ malcolm$ sudo diskutil unmountDisk /dev/disk3
Volume Untitled on disk3 unmounted

3. Then, find the ISO file.

malcolms-macbook-pro:~ malcolm$ cd Downloads/
malcolms-macbook-pro:Downloads malcolm$ ls -l
total 5408568
-rw-r--r--@  1 malcolm  staff  601817088 21 Jun 17:51 FreeBSD-11.0-RELEASE-i386-disc1.iso
-rwx------@  1 malcolm  staff  643112960 17 Jun 18:37 FreeBSD-11.0-RELEASE-i386-memstick.img
-rw-r--r--@  1 malcolm  staff  575899648 21 Jun 17:07 FreeNAS-11.0-RELEASE.iso
-rwx------@  1 malcolm  staff  539889664  4 May 18:27 FreeNAS-9.10.2-U3.iso

4. Then write the ISO file to the USB “disk” using the DD command.
Again, make double sure you are using the correct disk. I have used disk 3 here, your’s may be different.
Also, note the addition r in the disk name, its not required, but does make it faster.

malcolms-macbook-pro:Downloads malcolm$ sudo dd if=FreeNAS-11.0-RELEASE.iso of=/dev/rdisk3 bs=1m
549+1 records in
549+1 records out
575899648 bytes transferred in 69.073390 secs (8337504 bytes/sec)

5. Next eject the disk.

malcolms-macbook-pro:Downloads malcolm$ diskutil eject /dev/disk3
Disk /dev/disk3 ejected
malcolms-macbook-pro:Downloads malcolm$ 

6. All Done.

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