Howard Lowndes <[EMAIL PROTECTED]> uttered the following thing: > I have a disk image of a CompactFlash disk as a file on a PC. The image > was created by using dd. > > I know that the image has a partition table, a Linux (83) partition and > a Linux Swap (82) partition. The Linux partition is formatted ext2. > > I want to be able to mount the Linux partition rw somewhere onto the > PC's file system so that I can work on it using an editor.
The problem here of course is that the linux loopback filesystem mounter doesn't know anything about partition tables, it expects a filesystem, not an entire disk image. But all's not lost. Here's a way which will work on most (but not all) disks, assuming the other ideas presented fail. The partition table and MBR and other disk header gubbins is stored in the first few sectors on the disk. The trick is to find out just where the "interesting" partitions start. You can use fdisk to verify that the basic partition table stuff is there: # fdisk disk.img You must set cylinders. You can do this from the extra functions menu. Command (m for help): p Disk disk.img: 0 MB, 0 bytes 4 heads, 32 sectors/track, 0 cylinders Units = cylinders of 128 * 512 = 65536 bytes Device Boot Start End Blocks Id System disk.img1 * 1 244 15600 83 Linux Command (m for help): OK, so the interesting filesystem starts at the beginning. Next step, hunt for the ext2 magic number, using our friend hexdump and less: # hexdump disk.img|less [lots of hex] You need to find the beginning of the partition. To do that, look for the magic incantation: /ef53 0001 0001 Which will lead you to something like this: 0003fe0 d1aa 0cd9 14e9 72f4 042e e10d 9994 3db3 0003ff0 1af5 6ba4 72ba 8e08 8930 e292 65bb da56 0004000 0000 0000 0000 0000 0000 0000 0000 0000 * 0004400 0f40 0000 3cf0 0000 030c 0000 0a50 0000 0004410 0f12 0000 0001 0000 0000 0000 0000 0000 0004420 2000 0000 2000 0000 07a0 0000 133c 450f 0004430 13cd 450f 0004 001a ef53 0001 0001 0000 0004440 0198 450f 4e00 00ed 0000 0000 0001 0000 0004450 0000 0000 000b 0000 0080 0000 0034 0000 Notic it's on the third line from the bottom here (0004430). You've found a filesystem! Next, wind back four lines, to where all the zeros are. In this case, it starts at offset 0x4000. That's your filesystem start. Now determine this in decimal: $ printf "%d\n", 0x4000 16384 Then 'dd' the filesystem to another file, skipping til that point: dd if=disk.img of=disk.img1 bs=<number above> skip=1 Now, disk.img1 contains your complete filesystem (plus all of the trailing partitions, but that doesn't matter). You can now just mount it: $ mount -o loop disk.img1 /mnt/blah Problem solved :) BB -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
