ukify supports signing with multiple keys, so show an example of this, and just
let ukify print the calls to systemd-measure that will be done.
This also does other small cleanups:
- Use more realistic names in examples
- Use $ as the prompt for commands that don't require root (most don't).
Once we switch to operations that don't require a TPM, we should be able to get
rid of the remaining calls that require root.
- Ellipsize or linebreak various parts
- Use --uname. We warn if it is not specified and we have to do autodetection, so
let's nudge people towards including it rather than not.
Follow-up for e069c57f06.
If given, multiple initrds are concatenated into a temporary file which then
becomes the .initrd section.
It is also possible to give no initrd. After all, some machines boot without an
initrd, and it should be possible to use the stub without requiring an initrd.
(The stub might not like this, but this is something to fix there.)
