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.

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Purpose

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

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

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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.

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Basic Syntax

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

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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

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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

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Filesystem Support

• Raw, qcow2, vmdk, vdi, img

• Supports partitioned filesystems, LVM, and more.

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Unmounting Always unmount with:

guestunmount /mnt/vm

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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.