Save critical ext2/ext3/ext4 filesystem metadata to a file. More information: https://manned.org/e2image.
e2image /dev/sdXN path/to/image_file
stdout
:e2image /dev/sdXN -
e2image -I /dev/sdXN path/to/image_file
e2image -r /dev/sdXN path/to/image_file
e2image -Q /dev/sdXN path/to/image_file