Magic encoding

Magic Encoding is a little tool that allows you to quickly add or modify the magic comments that indicate source file encoding for an entire directory structure, please note that this tool only sets the comments, and does not perform any file encoding conversion whatsoever.

If you are looking for a way to convert files to a specific encoding, check out iconv (GNU)

I originally wrote this to get rid of “invalid multibyte char (US-ASCII)” errors when writing strings containing non ascii characters like éöàüèä in ruby on rails controllers


you can call the tool with default parameters like so


this will prepend every “.rb” file in the working directory (recursively) with the following line :

# -*- encoding : utf-8 -*-

Notes :

  • existing magic comments are replaced

  • the rest of the file remains unchanged

you can pass options to the tool to specify the desired encoding and the path where you want the tool to run, for example :

magic_encoding Shift-JIS /path/to/ruby/project

For more information on ruby >= 1.9 encoding features, check out