libguestfs – Manage virtual machine disk images

libguestfs is a C library tool for creating, accessing and modifying virtual machine disk images. You can look inside the disk images, modify the files they contain, create them from scratch, resize them, and much more.

The easy way to modify files in a VM’s disk image without powering on the VM, you could “mount” the disk image. You then would be able to modify the content of the disk image before unmounting it. libguestfs works with any disk image, including ones created in VMware, KVM, qemu, VirtualBox, Xen, and many other hypervisors, and ones which you have created from scratch.

Manage virtual machine disk images

Overview of libguestfs

There are many tools which use libguestfs:

guestfish – Interactive and scriptable shell.

guestmount – Mount filesystems from any guest or disk image on the host.

guestunmount – unmount guest filesystem

virt-alignment – scan Check alignment of partitions in guests.

virt-builder – quick image builder

virt-cat – Display a file from a guest.

virt-copy-in – Copy files and directories into a guest.

virt-copy-out – Copies files and directories out of a virtual machine disk image or named libvirt domain.

virt-customize – customize virtual machines

virtdf Display – disk usage of a guest.

virt-diff – Differences between files in two virtual machines

virt-edit – Edit a file in a guest.

virtfilesystems – Display the partitions, filesystems, logical volumes etc. in a guest.

virt-inspector – Inspect a guest and produce a report detailing the operating system, version, applications installed and more.

virt-format – erase and make blank disks

virt-ls – List files and directories in a guest.

virt-log – display log files

virt-make-fs – Make a new filesystem.

virt-rescue – Rescue mode for guests.

virt-resize – Resize a guest.

virt-sparsify – Make a disk sparse.

virtsysprep – Reset a guest to “factory configuration”.

virt-tar-in – Copy files from a tarball into a guest.

virt-tar-out – Copy files out of a guest into a tarball.

virt-win-reg – Export and merge Windows Registry entries from a Windows guest

libguestfs-test-tool — test libguestfs

libguestfs-make-fixed-appliance — make libguestfs fixed appliance

BoxGrinder & Oz Projects that can create guests from scratch.

OpenStack Uses libguestfs to inject files into guests.

virt-manager Uses libguestfs to display icons and applications in guests.

virt-v2v & virt-p2v Migrate between physical machines and different hypervisors


How to install libguestfs toolset on Linux

On Debian-based system:

# sudo apt-get install libguestfs-tools

On Red Hat-based system:

# sudo yum install libguestfs-tools



To mount qcow2 image volume at localfolder.

guestmount -a /path/to/qcow2/image -m <device> /local_path

The “-m <device>” option is used to specify a partition within the disk image.

run the following command.

#guestmount -a /images/testcentos.qcow2 -m /dev/sda1 /mnt

By default, the disk image is mounted in “read-write” mode. So you can modify any file in /mnt after mounting it.