Make "systemd-analyze dot" output only lines with units matching
given glob(7) patterns. Add --from-pattern and --to-pattern options.
Without any patterns all relationships are printed as before.
A relationship must match the follwing expression:
(isempty(from) || from[0] || from[1] || .. || from[n]) &&
(isempty(to) || to[0] || to[1] || .. || to[n]) &&
(isempty(P) || P[0] || P[1] || ... || P[n])
where from[] and to[] are lists of patterns provided with subsequent
--from-pattern and --to-pattern respectively. P[] is a list of additional
patterns provided after the "dot" subcommand.
