guestmount

guestmount is a utility from the libguestfs suite that allows you to mount a virtual machine disk image (or any supported guest filesystem) on your host system without booting the virtual machine.


Purpose

  • Access and manipulate files within VM disk images directly from the host.

  • Useful for inspection, recovery, or injecting/removing files.


Common Use Cases

  • Debugging or viewing guest log/config files.

  • Copying files into or out of a VM disk image.

  • Performing forensics on a VM image.

  • Rescuing files from an unbootable image.

  • Modifying or patching guest environments.


Basic Syntax

guestmount -a <disk.img> -m <mount_point> <host_directory>

Example: Mount /dev/sda1 from disk.qcow2 image in read-only mode to /mnt/vm:

guestmount -a disk.qcow2 -m /dev/sda1 --ro /mnt/vm

Use -i for automatic partition detection:

guestmount -a disk.qcow2 -i --ro /mnt/vm

Options

Option
Description

-a

Specify disk image

-i

Auto-detect guest OS and partitions

-m

Specify guest partition to mount

--ro

Mount as read-only

--rw

Mount with read/write access (use cautiously)

--trace

Enable backend call debugging


Filesystem Support

  • Raw, qcow2, vmdk, vdi, img

  • Supports partitioned filesystems, LVM, and more.


Unmounting Always unmount with:

guestunmount /mnt/vm

Security Notes

  • Use --ro to avoid accidental changes.

  • --rw may require root and can risk image corruption.

  • Do not expose guest filesystems to untrusted scripts or users.

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