from beebalm.com
macOS Instructions
Backup Raspberry Pi SD Card
1. Insert the SD card in your Mac using a USB or built-in card reader. Now open a Terminal window, and enter the command diskutil list. Try to identify the device ID of your SD card. For example, mine shows up as /dev/disk3.
2. Unmount your SD card:
diskutil unmountDisk /dev/disk3Here, replace disk3 with the name of your SD card that you identified in step 1.
3. Use the dd command to write the image to your hard disk. For example:
sudo dd if=/dev/disk3 of=~/raspbian_backup.img
Here, the if parameter (input file) specifies the file to clone. In my case, it is /dev/disk3, which is my SD card’s device name. Replace it with the device name of yours. The of parameter (output file) specifies the file name to write to. I chose raspbian_backup.img in my home directory.
Note: Be careful, and double check the parameters before executing the ddcommand, as entering the wrong parameters here can potentially destroy the data on your drives.
You will not see any output from the command until after the cloning is complete, and that might take a while, depending on the size of your SD card. You can then remove the SD card and use it in your Pi. Once you are ready to restore the backed up image, follow the instructions below:
Restore Raspberry Pi SD Card
1. Insert the SD card in your Mac. Open a Terminal window, and unmount it using the following command:
diskutil unmountDisk /dev/disk3Here, replace disk3 with the name of your SD that you identified in step 1 of the previous section.
2. Use the dd command to write the image file to the SD card:
sudo dd if=~/raspbian_backup.img of=/dev/disk3
This is like the command we used to make a clone, but reversed. This time, the input file if is the backup image, while the output file of is the SD card device.
Again, verify, and double-verify the parameters here, as entering the wrong command here will cause permanent data loss.
Once the write is complete, you will see a confirmation from dd. You can then remove the card from your Mac, and insert it back in the Raspberry Pi.
How to Shrink the Cloned Raspberry Pi Image (Linux-only)
As mentioned at the starting of the article, these methods create an image file that is equal to the total capacity of the SD card. For example, cloning an SD card with a capacity of 32GB will create an image file of 32 GB, even if only 5 GB is actually in use on the card. This is fine if you only have one or two such images, but any more than that (especially if you use an SSD) will cause you to run out of space.
To work around this limitation, we will use PiShrink, a script that automatically shrinks a Pi image that will then automatically resize to the max size of the SD card on boot. This also makes copying the image back onto the SD card much faster.
Unfortunately, this tool is only available on Linux. If you do not have Linux installed, you can install the latest version of Ubuntu or Linux Mint in a virtual machine, and run this script there. Here is how to use it:
1. Download the PiShrink script, and make it executable. In a Terminal, enter the following two commands:
wget https://raw.githubusercontent.com/Drewsif/PiShrink/master/pishrink.sh chmod +x ./pishrink.sh
2. Run the script, followed by the name of the image that you want to shrink.
sudo ./pishrink.sh ./raspbian_backup.img
3. The image will then be shrunk. Once done, you can write the shrunk image file to the SD card as mentioned in the methods listed above. For example, on Linux:
sudo dd if=~/raspbian_backup.img of=/dev/sdb