Change virtual machine password

Question

I have several virtual machines. I want to write a script that automates the following process ...

• It mounts the virtual machine (with linux as os) to say / mnt / image
• It modifies / etc / passwd (or the equivalent file) to change the user password.
• Unplug the virtual machine

Since I use libvirt, I have some qcow2 virtual machine images. To install the image on my ubuntu, I use the nbd module. Here are the commands I'm trying to do:

modprobe nbd max_part=63 qemu-nbd -c /dev/nbd0 image.qcow2 mount /dev/nbd0p1 /mnt/image 

This gives me an error:

 mount: special device /dev/nbd0p1 does not exist 

When I replace nbd0p1 with nbdo, I get the following error (although I'm not sure what I'm trying to do this)

 mount: you must specify the filesystem type 

Any suggestions that might be a problem ...?

Answer 1

[Not a direct answer to the question, but an alternative]
You can try to convert the qcow2 image to raw and then set the raw image.

convert:

 qemu-img convert -f qcow2 image.qcow2 -O raw image_raw.raw 

installation:

  sudo losetup /dev/loop0 image_raw.raw sudo kpartx -a /dev/loop0 sudo mount /dev/mapper/loop0p3 /mnt/image sudo mount /dev/mapper/loop0p2 /mnt/image/boot 

Answer 2

Make sure that /sys/modules/nbd/parameters/max_part has the expected value. If it is 0 or too low, the /dev/nbd0p1 , etc. Will not be available to the kernel. This can happen if the nbd kernel nbd has already been loaded (with a different max_part parameter) when modprobe starts.

You can fix this by unloading the module and promoting it again.

Answer 3

Could it be that the partition is not in the first MBR slot or is the extended partition used? Check if any other nodes of the nbdXpY device are nbdXpY , or run fdisk , and p copy the partition table.

Answer 4

I came across the same problem and the same error, but on vdi

 qemu-nbd -c /dev/nbd0 image.vdi 

the solution was simple for me, I just changed nbd0 to nbd1

 qemu-nbd -c /dev/nbd1 image.vdi 

and then:

 sudo mount /dev/nbd1p1 /media/eddie/virtual 

have worked.

Please leave a comment if this worked for you, and for what type of image.