huge file in /var/tmp

so have just found a huge file of 4gb in /var/tmp/.guestfs-1000/appliance.d/root

from brief googling i assume this is something to do with qemu? is this a vm cache file? i have just started all my VMs and the file has not updated and so if assumptions correct, this must be dead cruft?

most importantly can i safely delete it?

Look at the file date/time.
If it’s at least a few hours old, I’d say it’s likely safe to delete.

If you’re in the habit of suspending or hibernating Guests from within a Guest, don’t.
That’s one of the best ways to corrupt a Guest.

Always do one of the following

  • Shutdown the Guest completely(within a Guest)
  • Not from within the Guest, but in the HostOS virtualization manager, you can suspend a Guest. Be aware that this will wreak havoc with the Guest’s time, so do a time sync when you resume.