How to make an Image of my Solid State Drive I have installed macOS, Linux and Windows to my MacBook Air. It was hard installing a triple boot system because each of issues with their boot loaders, but now everything works fine.

I want to save the image of my SSD to an external hard drive. How can I do that?
You can use the program dd to create a disk imgage of an entire disk (including hidden boot partitions etc.)
I use a GParted live CD (linux) to boot from so the disk I want to clone is not in use.

Once booted I go first go to GParted to get the deviceid (/dev/sda or something like that).
Then I open terminal to use dd. Be careful dd will erase your disk if you use "of=/dev/sdX" with the disk you want to copy.

To create an uncompressed img I use: (do not forget to change the drive letter!)

dd bs=4M if=/dev/sdb of=/mnt/bla/image1-`date +%d%m%y`.img


but you can also zip 

dd bs=4M if=/dev/sdb | gzip &gt; /mnt/Raspberry/test_dd/image1-`date +%d%m%y`.img.gz


"if=" is the source file or disk
"of=" is the destination
if no "of=" is used it will stream it to std. out with you can pipe thru (|)