So, you have a disk image file, and you want to make some partition modifications to prep it before copying to a new hard drive or SSD of a similar but slightly different size. How do you do that? It’s actually very easy, if I just give your the commands.
sudo losetup -P /dev/loop0 disk1.img
sudo gparted /dev/loop0
So, what does this mean? First of all, gparted can take a device
file, so even though it won’t iterate loop device files by default,
you can ask it to operate on loop device files specifically. Second,
you can specify the -P option to force the kernel to create
partition device files for each partition in the loop-mounted disk
image. I should have known this one earlier, this is a much easier
way to loop-mount partitions from a disk image file.
partprobe can be used to refresh the partition table and partition
device files for physical drives, but it doesn’t work for loop
devices.
20200918/DuckDuckGo gparted loop device
20200918/https://superuser.com/questions/103508/do-ntfsresize-and-gparted-work-on-a-disk-image-mounted-through-the-loop-device#103544
20200918/DuckDuckGo mknod loop device
20200918/https://unix.stackexchange.com/questions/98742/how-to-add-more-dev-loop-devices-on-fedora-19#198637
20200918/https://stackoverflow.com/questions/1419489/how-to-mount-one-partition-from-an-image-file-that-contains-multiple-partitions
20200918/DuckDuckGo make disk image file appear as multiple partitions
20200918/DuckDuckGo linux make disk image file appear as multiple partitions
20200918/https://unix.stackexchange.com/questions/342463/how-to-mount-multiple-partitions-from-disk-image-simultaneously
20200918/DuckDuckGo kernel rescan partition table loop device
20200918/https://www.cyberciti.biz/tips/re-read-the-partition-table-without-rebooting-linux-system.html