Lowcasing option works for english letters but doesn't work for russian. Easy way to reproduce: crabman@crmlp ~/temp/temp $ touch qweQWEйцуЙЦУ crabman@crmlp ~/temp/temp $ renamexm --lowcase qweQWEйцуЙЦУ crabman@crmlp ~/temp/temp $ ls qweqweйцуЙЦУ crabman@crmlp ~/temp/temp $