How to mount partitioned disk image files
Mounting unpartitioned disk image files in Linux is easy. You just execute ‘mount -o loop disk.img /mnt’ right?
Well, if your disk image file happens to contain partitions its a little bit trickier. Here is what you need to do:
First you attach the disk image to the first available loopback device
Next, we get a listing of the partition table it contains:
Disk /dev/loop0: 4294 MB, 4294967296 bytes
133 heads, 62 sectors/track, 1017 cylinders, total 8388608 sectors
Units = sectors of 1 * 512 = 512 bytes
Device Boot Start End Blocks Id System
/dev/loop0p1 62 7998619 3999279 83 Linux
/dev/loop0p2 7998620 8386181 193781 82 Linux swap / Solaris
Now for the juicy part. You attach one the partitions contained in the disk image to yet another loopback device by specifying the offset of the partition.
The -o option to losetup tells it the number of bytes to skip at the beginning of the file. To get that number, you multiply the number of bytes per unit (in this case, 512) by the ‘Start” value of the parititon (in this case, 62). So our -o value will be 31744.
Loop device is /dev/loop2
Looks good so far. Now mount it.
Thats it. You should now be able to get at all the files on that partition.