libguestfs tools howto guide for managing virtual machine images.
libguestfs-tools aka guestfs tools has a lot of tools that make this very easy for you. You can easily mount partitons from an image with some of the commands below.
To mount a partition
#mount the kvmuser102821.img image and the /dev/sda1 partition from it to the local directory "mount"
guestmount -a kvmuser102821.img -m /dev/sda1 mount
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