I made an image of my entire disk with

dd if=/dev/sda of=/media/external_media/sda.img

Now 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_image

obviously 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)

up vote 123 down vote accepted

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.img

Now the partition resides on /dev/loop0. You can fsck it, mount it etc

sudo fsck -fv /dev/loop0
sudo mount /dev/loop0 /mnt


sudo umount /mnt
sudo losetup -d /dev/loop0
  • Thank you so much! Worked like a charm! You made my day (and saved an innocent Ocelot from being brutally deleted ;P) – Nicola Feltrin Oct 21 '11 at 17:10
  • 8
    At least on bash, the shell can even do the math for you: sudo losetup -o $((56*512)) /dev/loop0 sda.img – Enno Gröper Jan 13 '13 at 11:55
  • This is not just helpful, this is absolutely awesome. – andho Feb 18 '13 at 13:38
  • What if there's a .img1 and .img2? "win8.raw1 * 2048 718847 358400 7" and "win8.raw2 718848 52426751 25853952 7" – Enkouyami Oct 4 '13 at 1:16
  • 3
    Even simpler: mount -o loop,offset=$((56 * 512)) sda.img /mnt. Source: madduck.net/blog/… – ostrokach Sep 10 '15 at 19:33

Update for Ubuntu 16.04: With the new losetup this is now easier:

sudo losetup -Pf disk_image.raw

See 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 3084288

This 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 /mnt

Alternatively, the block device is detected by Nautilus and you can mount it from the side bar:

enter image description here

When you are done, unmount what you mounted and remove the device mapping:

$ sudo umount /mnt
$ sudo kpartx -d disk_image.raw
  • Excellent answer, quick and easy, avoiding the multiplication step is nice – Elder Geek May 13 '14 at 19:11
  • sudo apt-get install kpartx - to get access to kpartx. The kpartx link in the beginning of the post is a 'trap' in my opinion. Links that imply installing software is a no-no. – Hannu Jul 31 '14 at 18:26
  • 1
    @Hannu, links that integrate with Software Center are a common practice on askubuntu, though in this particular case the typical icon could be added and the URL should be updated. – Joni Aug 8 '14 at 8:46
  • losetup -Pf had been previously mentioned by askubuntu.com/a/496576/52975 I recommend that you at least link to that answer. – Ciro Santilli 新疆改造中心 六四事件 法轮功 Jun 22 '16 at 10:27

Edit : 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 device

So just run

$ sudo losetup -f --show -P /path/to/image.img

to 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.

  • 2
    Where do I find this version of losetup ? The one I have in Ubuntu 14.04 has a manpage from July 2003 (util-linux) and no ` -P ` option (or anything else) for scanning partitions. – Hannu Jul 31 '14 at 18:26
  • 1
    Sorry, I made a mistake, I've been using this option on Arch Linux which comes with a more recent version of util-linux package. It seems that Ubuntu is sadly stuck on version 2.20.1 which has been released on january 2012 ! The --partscan option has been introduced in util-linux 2.21 – Ludovic Ronsin Aug 4 '14 at 15:09
  • 1
    Well, gnome-disks has an option to mount a disk image and it's partitions. (<- that is for installing and bash/Terminal use, Disksin the dash finds it too). – Hannu Aug 4 '14 at 15:35
  • 2
    This should be the accepted answer ... – matthid Apr 23 '15 at 12:54
  • @matthid Is it even possible to change an accepted answer? This is good (and the kpartx answer is actually dependent on this version of losetup), but it's almost three years newer than the accepted answer—which was the way to do it at the time. – Auspex Dec 26 '15 at 23:10

Try gnome-disk-image-mounter:

gnome-disk-image-mounter sda.img

No sudo required. It will be mounted at /media/your_user_name/partition_name, just like USB drives.

  • Was working well on 16.04. I just installed a fresh 18.04 and the tools asks for sudo password in order access the /dev/loopXX virtual device :( – Laurent Jun 28 at 23:36

losetup -P automation

losetup -P is the best method starting in Ubuntu 16.04 as mentioned at https://askubuntu.com/a/496576/52975 , here are functions to automate if further. Usage:

$ los my.img

$ ls /mnt/loop0p1

$ 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


los() (
  dev="$(sudo losetup --show -f -P "$img")"
  echo "$dev"
  for part in "$dev"?*; do
    if [ "$part" = "${dev}p*" ]; then
    dst="/mnt/$(basename "$part")"
    echo "$dst"
    sudo mkdir -p "$dst"
    sudo mount "$part" "$dst"
losd() (
  for part in "$dev"?*; do
    if [ "$part" = "${dev}p*" ]; then
    dst="/mnt/$(basename "$part")"
    sudo umount "$dst"
  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_part

says 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=31

to a file in /etc/modprobe, or:


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.img

it 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.img

Then 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/md2p1
  • That's a funny trick :) – Johan Boulé Dec 16 '17 at 2:10

The 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 $MOUNTPOINT

The 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 https://github.com/AlexanderAmelkin/mountimg and use like this:

mountimg /media/external_media/sda.img 2 /media/sda_image

You 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-8

When you're done with the partition, simply umount it:

umount /media/sda_image

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