I made an image of my entire disk with
dd if=/dev/sda of=/media/external_media/sda.imgNow the problem is I'd like to mount an ext4 filesystem that was on that disk but
mount -t ext4 -o loop /media/external_media/sda.img /media/sda_imageobviously gives a superblock error since the image contains the whole disk (MBR, other partitions) not just the partition I need. So I guess I should find a way to make the disk image show up in the /dev/ folder...
Does anyone know how to do that?
PS: I can always dd back the image to the original disk, but that would be very inconvenient (I updated the OS and I'd like to keep it as it is)
9 Answers
Get the partition layout of the image
$ sudo fdisk -lu sda.img
...
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
... Device Boot Start End Blocks Id System
sda.img1 * 56 6400000 3199972+ c W95 FAT32 (LBA)Calculate the offset from the start of the image to the partition start
Sector size * Start = (in the case) 512 * 56 = 28672
Mount it on /dev/loop0 using the offset
sudo losetup -o 28672 /dev/loop0 sda.imgNow the partition resides on /dev/loop0. You can fsck it, mount it etc
sudo fsck -fv /dev/loop0
sudo mount /dev/loop0 /mntUnmount
sudo umount /mnt
sudo losetup -d /dev/loop0Update for Ubuntu 16.04: With the new losetup this is now easier:
sudo losetup -Pf disk_image.rawSee the rest of the answer for older versions of Ubuntu.
An easy solution is using kpartx: it will figure out the partition layout and map each to a block devices. After that all you have to do is mount the one you want.
Open Terminal, locate the disk image, and enter this command:
$ sudo kpartx -av disk_image.raw
add map loop0p1 (252:2): 0 3082240 linear /dev/loop0 2048
add map loop0p2 (252:3): 0 17887232 linear /dev/loop0 3084288This created loop0p1 and loop0p2 under /dev/mapper. From the output you can see the sizes of the partitions which helps you identify them. You can mount the one you want with:
$ sudo mount /dev/mapper/loop0p2 /mntAlternatively, the block device is detected by Nautilus and you can mount it from the side bar:
When you are done, unmount what you mounted and remove the device mapping:
$ sudo umount /mnt
$ sudo kpartx -d disk_image.rawEdit : works with util-linux >=2.21. At the time of writing ubuntu ships with version 2.20 only
From man losetup :
-P, --partscan force kernel to scan partition table on newly created loop deviceSo just run
$ sudo losetup -f --show -P /path/to/image.imgto create device nodes for every partition of your disk image on the first unused loop device and print it to stdout.
If using /dev/loop0 device it will create at least /dev/loop0p1 that you will be able to mount as usual.
Try gnome-disk-image-mounter:
gnome-disk-image-mounter sda.imgNo sudo required. It will be mounted at /media/your_user_name/partition_name, just like USB drives.
losetup -P automation
losetup -P is the best method starting in Ubuntu 16.04 as mentioned at , here are functions to automate if further. Usage:
$ los my.img
/dev/loop0
/mnt/loop0p1
/mnt/loop0p2
$ ls /mnt/loop0p1
/whatever
/files
/youhave
/there
$ sudo losetup -l
NAME SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE DIO
/dev/loop1 0 0 0 0 /full/path/to/my.img
$ # Cleanup.
$ losd 0
$ ls /mnt/loop0p1
$ ls /dev | grep loop0
loop0Source:
los() ( img="$1" dev="$(sudo losetup --show -f -P "$img")" echo "$dev" for part in "$dev"?*; do if [ "$part" = "${dev}p*" ]; then part="${dev}" fi dst="/mnt/$(basename "$part")" echo "$dst" sudo mkdir -p "$dst" sudo mount "$part" "$dst" done
)
losd() ( dev="/dev/loop$1" for part in "$dev"?*; do if [ "$part" = "${dev}p*" ]; then part="${dev}" fi dst="/mnt/$(basename "$part")" sudo umount "$dst" done sudo losetup -d "$dev"
)loop module max_part config
This is a decent method before 16.04.
loop is a kernel module, built into the kernel in Ubuntu 14.04.
If you configure it right, Linux automatically splits up the devices for you.
cat /sys/module/loop/parameters/max_partsays how many partitions loop devices can generate.
It is 0 by default on Ubuntu 14.04 which is why no auto-splitting happens.
To change it, we can either add:
options loop max_part=31to a file in /etc/modprobe, or:
GRUB_CMDLINE_LINUX="loop.max_part=31"to /etc/default/grub and then sudo update-grub.
How to set a module parameter is also covered at: How to add kernel module parameters?
After a reboot, when you do:
sudo losetup -f --show my.imgit mounts the image to a /dev/loopX device, and automatically mounts the partitions to /dev/loopXpY devices.
So this is the most convenient method if you are willing to reboot.
See also
Use losetup to attach the whole disk image.
# sudo losetup /dev/loop2 sda.imgThen use mdadm to create an md device and block devices will be created for all of the partitions.
# sudo mdadm --build --level=0 --force --raid-devices=1 /dev/md2 /dev/loop2
mdadm: array /dev/md2 built and started.Now you should see the partition devices.
nile-172-b0fef38-76:/mnt/sdb1 # ls -l /dev/md2*
brw-rw---- 1 root disk 9, 2 Oct 10 12:37 /dev/md2
brw-rw---- 1 root disk 259, 0 Oct 10 12:37 /dev/md2p1The simplest way, in my opinion, is using mount -o loop,offset=... as mentioned in this answer on StackOverflow. The idea is as follows:
fdisk -l $IMAGE
# calculate the offset in bytes
mount -o loop,offset=$OFFSET $IMAGE $MOUNTPOINTThe method is best because it doesn't require deleting the loop device after you umount the mounted partition.
To further simplify the task (which is needed if you do it often), you may use my script mountimg to do everything for you. Just get it from
and use like this:
mountimg /media/external_media/sda.img 2 /media/sda_imageYou may as well specify filesystem type and any other additional mount options if you like:
mountimg /media/external_media/sda.img 2 /media/sda_image -t vfat -o codepage=866,iocharset=utf-8When you're done with the partition, simply umount it:
umount /media/sda_imageHere's a user-friendly and interactive way that requires that the excellent fzf utility is installed, as well as sudo.
First add this function to your .bashrc or .zshrc:
pmount() { sudo mount -o loop,offset=$(($(sudo fdisk -lu "$1" | sed -n '/^Device/,/^$/p' | tail -n+2 | fzf | sed -E -e 's/[[:blank:]]+/ /g' | cut -d' ' -f2- | sed 's@^[^0-9]*\([0-9]\+\).*@\1@') * 512)) "$1" "$2"; }Then reload your shell (or type $SHELL).
You can then mount .img files with this command:
pmount my.img /mntA list pops up where you can select which permision you wish to mount, using the arrow keys and then pressing return.
Unmount with sudo umount /mnt.
How do I open / mount my ISO file when normal methods throw this error?wrong fs type, bad option, bad superblock on /dev/loop0, missing codepage or helper program, or other error.
I tried several methods but they all fail somehow.
I'm actually answering this problem (Unable to mount an ISO file), which problem I also have, and have just solved, but the original question has been closed, and refers to this question, even though they seem different.
I feel that curators often close questions for indecipherable reasons, however, I don't have any choice but to use the closure and reference given. If it's wrong, perhaps the previous question can be re-opened, and this answer put there, where I'd like it to be? Since this user edited the original question, I suspect he might have been the one to close the original:
Anyway, leaving the filing issues behind, here's an example of trying to mount the ISO:
$ sudo mount -o ro,loop -t iso9660 nero.iso /mnt
mount: /mnt: wrong fs type, bad option, bad superblock on /dev/loop0, missing codepage or helper program, or other error.I called the ISO nero.iso because using the file command revealed the ISO is an artifact of the "Nero" CD Burning software, not that that helps any:
$ sudo file nero.iso
nero.iso: Nero CD image at 0x4B000 UDF filesystem data (version 1.5) 'nero'After trying a few different things I came across a reference to the software iat which says it "converts many CD-ROM image formats to iso9660". Woah. It immediately, and effortlessly, works:
$ sudo apt install iat
$ man iat
$ iat nero.iso out.iso
Iso9660 Analyzer Tool v0.1.3 by Salvatore Santagati
Licensed under GPL v2 or later
Detect Signature ISO9660 START at 339968
Detect Signature ISO9660 END at 342016 Image offset start at 307200 Sector header 0 bit Sector ECC 0 bit Block 2048
DoneReally? Now the mount command silently completes:
$ sudo mount -o ro,loop out.iso /mntAnd, Behold, the ISO is mounted, and Handbrake will now happily rip the content.
Thank you, Salvatore Santagati. I've always liked coffee... and ice-cream.
I hope anyone else with this problem is able to follow the reference from the previous question and find this answer despite the obscure filing!
