Sed-like configuration file editing with virt-edit

A new option in virt-edit lets you non-interactively edit files in a virtual machine, somewhat like using sed or perl -pe. For example, change the init default level to 3:

virt-edit test.img /etc/inittab -e 's/^id:.*/id:3:initdefault:/'

Delete the root password from a VM:

virt-edit test.img /etc/passwd -e 's/^root:.*?:/root::/'