Because I have installed a bunch of things for a larger project on my Raspberry Pi 3 Model B, I would like to backup the entire (bootable) SD card on my Mac.
I tried to insert the SD card into my Mac and subsequently copy the whole SD card image using
sudo dd bs=4m if=/dev/sdb of=raspbian.img, as specified in: https://www.raspberrypi.org/documentation/linux/filesystem/backup.md
However, when I plug the SD card into my Mac (running the latest OS), it tells me it cannot read the medium and gives me 3 options: Initialize... | Ignore | Eject.
I tried clicking "Ignore" and ran the command
sudo dd bs=4m if=/dev/sdb of=raspbian.img, while I replaced the if path correctly (using "disk2" instead). It then tells me that there is an input/output error.
The SD card is booting up my Raspberry Pi completely ok, however, so I do not think it is corrupted.
Is it safe to let my Mac "Initialize..." the SD card and will this help me to back it up?
How can I back up the SD card in this scenario without losing the current state of it?
Help on this would be very much appreciated.