linux 🐧

Creating boot USB sticks/microcards on macOS

A real quick-and-dirty way.

1º. Get an operating system image

You gotta get a *.img file somehow. Most distributions distribute them as compacted versions (tar, gzip, xz, etc.).

If all you've got is a *.iso file, convert it to *.img using hdiutil:

hdiutil convert -format UDRW -o /output.img /path/to/your/file.iso

2º. Prepare your removable

Format your removable as FAT32.

3º. Now, find the physical address of your removable

Plug your removable into your macOS system and run:

diskutil list

You'll see something like this:

/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *100.0 GB   disk0
   1:                        EFI EFI                      79.0 MB   disk0s1
   2:          Apple_CoreStorage HD                       99.0 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3

/dev/disk1 (internal, virtual):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS HD                      +98.0 GB   disk1
                                 Logical Volume on disk0s2
                                 A1B2C3D4-E5F6-G7H8-J9K1-0L11M12N13P1
                                 Unencrypted

/dev/disk2 (external, physical):
  #:                       TYPE NAME                    SIZE       IDENTIFIER
  0:     FDisk_partition_scheme                        *2.0 GB     disk2
  1:                 DOS_FAT_32 SD                      2.0 GB     disk2s1

Now figure out which one is the physical address of your removable disk.

TL;DR: diskutil list lists all your disks, both physical and virtual. You'll have to figure out which physical disk is your removable, but you can generally check it through the storage capacities (in the example, it's a microsd capable of 2GB storage).

4º. Copy the raw data to your disk

After identifying the physical address of your removable, run:

diskutil unmountDisk <your removable disk address>

According to the example above, it would be:

# diskutil unmountDisk /dev/disk2

Then use dd to copy the contents your ``*.img` file into your disk:

sudo dd if=path/to/your/file.img if=<your-removable-disk> bs=1ms

💡 Use GNU dd to get progress reporting

The dd binary that ships in macOS does not report progress, but the GNU's does. You can install it through Homebrew's pkg coreutils (brew install coreutils).

GNU's dd will then be available in your $PATH as gdd.

With GNU dd in place, you can run it just like you would do in dd, with an additional option, status=progress:

gdd bs=1M status=progress if=./your-image.img of=/dev/disk2

Additional resources: