Exact description of convmv from project site.
convmv converts filenames (not file content), directories, and even whole filesystems to a different encoding. This comes in very handy if, for example, one switches from an 8-bit locale to an UTF-8 locale or changes charsets on Samba servers. It has some smart features: it automagically recognises if a file is already UTF-8 encoded (thus partly converted filesystems can be fully moved to UTF-8) and it also takes care of symlinks. Additionally, it is able to convert from normalization form C (UTF-8 NFC) to NFD and vice-versa. This is important for interoperability with Mac OS X, for example, which uses NFD, while Linux and most other Unixes use NFC. Though it's primary written to convert from/to UTF-8 it can also be used with almost any other charset encoding. Convmv can also be used for case conversion from upper to lower case and vice versa with virtually any charset. Note that this is a command line tool which requires at least Perl version 5.8.0.This tool is not available in all distributions by default.
How to lower all file names in direcotry
convmv --lower -r /path/to/your/files/depending on the files you might have to add your charset here, too:
convmv --lower --nosmart -r -f utf8 /path/to/your/files/
How to fix file names encoding
convmv --lower --nosmart -r -f iso8859-2 -t utf8 /path/to/your/files/Other options which may be useful: