30
Connect the SD card reader with the SD card inside.
Run
df -h
again and look for the new device that wasn't listed last time.
Record the device name of the filesystem's partition, for example
/dev/disk3s1
.
Unmount the partition so that you will be allowed to overwrite the disk:
sudo diskutil unmount /dev/disk3s1
(or open Disk Utility and unmount the partition of the SD card (do not eject it,
or you will have to reconnect it)
Using the device name of the partition, work out the raw device name for the
entire disk by omitting the final "s1" and replacing "disk" with "rdisk". This is
very important as you will lose all data on the hard drive if you provide the
wrong device name. Make sure the device name is the name of the whole SD
card as described above, not just a partition of it (for example, rdisk3, not
rdisk3s1). Similarly, you might have another SD drive name/number like
rdisk2 or rdisk4; you can check again by using the
df -h
command both
before and after you insert your SD card reader into your Mac. For example,
/dev/disk3s1
becomes
/dev/rdisk3
.
In the terminal, write the image to the card with this command, using the raw
disk device name from above. Read the above step carefully to be sure you
use the correct rdisk number here:
sudo dd bs=1m if=image.img of=/dev/rdisk3
If the above command reports an error (
dd: bs: illegal numeric value
),
please change
bs=1m
to
bs=1M
.
If the above command reports an error
dd: /dev/rdisk3: Permission
denied
then that is because the partition table of the SD card is being
protected against being overwritten by MacOS. Erase the SD card's partition
table using this command:
sudo diskutil partitionDisk /dev/disk3 1 MBR "Free Space"
"%noformat%" 100%
That command will also set the permissions on the device to allow writing.
Now try the
dd
command again.
