Loop Devices in linux - Mount disk images
Well one have programs out there for windows to mount ISO images etc. to the virtual drive. You can then use those to perform task that might not be possible without mounting the image. Softwares like Daemon tools and PowerISO are very good examples of such softwares.
Loop Devices
Loop devices are pseudo devices available under linux commonly found under /dev/ with the name of loopN where N is a number like 0,1,2,3,4 etc.
Mounting a disk image
You can make use of some commands to attach an ISO image first with the loop device and then mount the loop device like you do mount any other device in your computer.
To revert to the previous state you do the reverse i.e you first unmount the device and then you detach the image from your loop device.
There is this utility losetup available in linux systems which is
used to attach the disk image with the loop device. You require sudo
priviliges to do so. Lets assume you have an ISO image in your home
folder with the name Ubuntu.iso and you want to mount it like you
have made a DVD or CD out of this image first and reading it then. Do
following :
sudo losetup /dev/loop0 ~/Ubuntu.iso
This will attach the ISO image with the loop device. If you are using a GUI and a file manager like nautilus, you can see that this Ubuntu is added under devices in nautilus, this is because the nautilus has subscribed to udev(which is responsible to tell various information about the attached devices) which keep telling it about the devices that gets registered with it.
Finally to mount the device, you can simply click on the device shown in nautilus to mount it and see its contents, or you can mount it the traditional way in CLI as :
sudo mount /dev/loop0 /mnt/
This will mount your image under /mnt and you should be able to read
it.
To revert the whole procedure, first unmount the image as :
sudo umount /dev/loop0
and then detach the ISO image from the loop device 0 as :
sudo losetup -d /dev/loop0
and you are done. Everything back to normal !! Enjoy mounting images without any need of external software.
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