Match the regexp limiting patterns without regard to letters case.
+--basic-regexp::
+
+ Consider the limiting patterns to be basic regular expressions;
+ this is the default.
+
-E::
--extended-regexp::
Consider the limiting patterns to be fixed strings (don't interpret
pattern as a regular expression).
+--perl-regexp::
+
+ Consider the limiting patterns to be Perl-compatible regexp.
+ Requires libpcre to be compiled in.
+
--remove-empty::
Stop when a given path disappears from the tree.