uml_moo

uml_moo merges a COW file with its backing file. It can do an in-place merge, where the new blocks from the COW file are written directly into the backing file, or create a new file, leaving the existing backing file unchanged.

Create a new merged file like this:

uml_moo [-b backing file] COW-file new-backing-file

Here's the usage for doing an in-place merge:

uml_moo [-b backing file] -d COW-file

The -b switch is used when the COW file doesn't correctly specify the backing file. This can be required when the COW file was created in a chroot jail, in which case the path to the backing file stored in the COW file header will be relative to the jail.