Say you’ve made an image of a partition. You might know that you can use
mount -o loop to mount the image. But what do you do if you’ve made an image of an entire disk? Many people will “carve out” the partition using dd with the skip and count options. You can save time and disk space by using the offset option with
Using pretty much any partition manager (parted, fdisk, sfdisk, etc.), find out the byte boundaries of your desired partition. For example:
GNU Parted 2.3 Using /mnt/external/vol2.work/vol2-1.big_image Welcome to GNU Parted! Type 'help' to view a list of commands. (parted) unit Unit? [compact]? B (parted) print Model: (file) Disk /mnt/external/vol2.work/vol2-1.big_image: 40020664320B Sector size (logical/physical): 512B/512B Partition Table: msdos Number Start End Size Type File system Flags 1 32256B 32901119B 32868864B primary ext3 boot 2 32901120B 567544319B 534643200B primary linux-swap(v1) 3 567544320B 38461409279B 37893864960B primary linux-swap(v1) 4 38461409280B 40015987199B 1554577920B primary ntfs
Two swap partitions? That larger one might need some work, but the NTFS partition looks like it might be okay.
sudo mount -o ro,loop,offset=38461409280 -t auto vol2-1.big_image /mnt/test2
And it works! The (apparently quite old) NTFS filesystem is mounted.
$ ls /mnt/test2 arcldr.exe CONFIG.SYS NTDETECT.COM Program Files arcsetup.exe Documents and Settings ntldr System Volume Information AUTOEXEC.BAT IO.SYS pagefile.sys WINNT boot.ini MSDOS.SYS Paragon HDM