How to create .img file

An IMG file contains a raw dump of the content of a disk. We will use losetup to associate loop device with a file and mount it to work with.

1. Pre-allocate img file (stuff.img) of the size you need (10M):

   dd if=/dev/zero of=/tmp/stuff.img bs=1M count=10
   

2. Setup a loop device:

   losetup /dev/loop0 /tmp/stuff.img
   

3. Create ext3 file system on loop device:

   mkfs.ext3 /dev/loop0
   

4. Mount it:

   mount /dev/loop0 /mnt
   

Once you are done:

1. Unmount file system:

   umount /mnt
   

2. Delete loop device:

   losetup -d /dev/loop0