[TriLUG] Using Loop Device

[James c. Jones]

Alan,

Thanks for the information. I will try it tonight. Hopefully, I will
have a good report -- or at least error messages that are meaningful.

jcj
Alan Porter wrote:
>> I have a dd file that I wish to extract some items. I was informed
>> that using a loop device was the way to do this.
>>     
>
> The important thing here is to know whether the image was made from
> a PARTITION or a DISK.
>
> If it was a DISK, then it contains a partition table and one or more
> partitions.  If it was a partition, then it contains just one partition.
>
> You can tell by doing a "file imagefile.img" and see whether it
> contains a filesystem or a partition table (the words they use are
> funny, but it'll say something like "x86 boot sector").
>
> PARTITION
>
> If you have a partition image, just do this:
>    [aporter at sti]$ mount -o loop -t ext3 imagefile.img /mnt/image
>
> The -o loop will set up the loop device for you.
>
> DISK
>
> If you have an entire disk image, just do this:
>
>    [aporter at sti]$ /sbin/fdisk -u -l imagefile.img 2> /dev/null
>    Disk image.usb: 0 MB, 0 bytes
>    64 heads, 32 sectors/track, 0 cylinders, total 0 sectors
>    Units = sectors of 1 * 512 = 512 bytes
>
>    Device          Boot  Start   End      Blocks   Id  System
>    imagefile.img1  *     32      1079295  539632   83  Linux
>
> Make a note of the sector size ("Units") and the starting sector ("Start").
>
> [aporter at sti]$ mount -t ext3 -o loop,offset=$((32*512)) imagefile.img /mnt/image
>
>
> Hope this helps.
>
>
> Alan
>
>
>
>
>
> .
>
>
>
>
>