Re: mounting a FAT32 disk image?
Is the image just a "partition" on the SD, or the entire SD? You can sudo mount an image of a CD/DVD or partition or filesystem in a file, using -o loop option, but I do not know if that works for an image of an entire drive. In a terminal see man mount then type /loop and keep hitting n until you get to THE LOOP DEVICE.
But unless you reformatted an SD card or dd'd a CD image to it, the default filesystem type would usually be -t vfat, not -t iso9660.
The most common place to mount something in Ubuntu is to sudo mkdir a mount point in /media (or you could create the mount point in /mnt). I added /media/vdisk as a mount point for manually loop mounted image files.
Example of loop mounting the persistent data file (casper-rw) of bootable live/install iso on USB stick:
I was not sure how to mount an entire boot drive image (a slim lxde Debian ARM image to boot a Raspberry Pi from SD, containing /boot and / partitions). But I set up a similar Debian system with lxde in VirtualBox and used VirtualBox to add the Raspian image as another hard drive. Then I used /etc/fstab in the VBox Debian to mount the /boot and / partitions of the image to see what was on them.
efflandt@XPS8100-1204:~$ ls /media
efflandt@XPS8100-1204:~$ ls -a /media/vdisk
efflandt@XPS8100-1204:~$ ls /media/SONY8GB
autorun.inf casper dists install md5sum.txt pool README.diskdefines wubi.exe
boot casper-rw efi ldlinux.sys pics preseed syslinux
efflandt@XPS8100-1204:~$ sudo mount -t ext3 /media/SONY8GB/casper-rw /media/vdisk -o loop
efflandt@XPS8100-1204:~$ ls /media/vdisk
boot cdrom etc home lib lost+found media mnt rofs target tmp usr var
i5 650 3.2 GHz, 8 GB, nvidia GTX 1060, 32" 1080p & assorted older computers