Ruby FileUtils.mv invalid multibyte character

Ruby FileUtils.mv invalid multibyte character

I'm use FileUtils.mv to move folder like this:
FileUtils.mv("/home/sean/_site/", "/home/sean/projects/_site/")
but that not working, because the _site folder contains the following files:
?????ʼ???????????????
????fedora????ʱ??ʾcannot-open-font-file-true?İ취
?˿?????firefox????????
?ȸ?gaeӦ???̵?
??ǧ??ǧѰ???ⲿ??Ʒ???ɹ??ĵط?
but when I use system command then everything is ok, like this:
mv /home/sean/_site /home/sean/projects/_site
My system is ubuntu 12.04 LTS server, ruby is 2.0.0p195.