in reply to dir match, dir may or may not appear

In your regex [^/]+{0,1} does not make sense if I understand it correctly, basically you say
anything but a slash, at least one time, then you say at least 0 time at most 1... you gotta choose which you want, either it is

[^/]+ or [^/]? (equivalent to {0,1}) For what you want to do I'd say: m#\A/usr/([^/]+/)?bin#