Ruby 1.9.2: irb throws ArgumentError: invalid byte sequence in UTF-8 when entering German Umlaut

Question

I want to enter German Umlauts in my irb but get a weird error. I can enter any character of äöü without problems, but each of ÄÖÜß leads to the following error:

$ irb
ruby-1.9.2-p136 :001 > ? # here I entered Ü but it displays only ?
/Users/lorenz/.rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/irb/ruby-lex.rb:728:in
`block in lex_int2': invalid byte sequence in UTF-8 (ArgumentError)

I have looked at a lot of SO questions regarding Ruby, rvm, and UTF-8 but none helped. Most are tied to rails or database configuration. I specifically checked the following:

locale is set correctly

$ locale
LANG="de_DE.UTF-8"
LC_COLLATE="de_DE.UTF-8"
LC_CTYPE="de_DE.UTF-8"
LC_MESSAGES="de_DE.UTF-8"
LC_MONETARY="de_DE.UTF-8"
LC_NUMERIC="de_DE.UTF-8"
LC_TIME="de_DE.UTF-8"
LC_ALL="de_DE.UTF-8"

Terminal.app is set to Unicode (UTF-8) and Encoding.default_external is set correctly:

$ irb
ruby-1.9.2-p136 :001 > Encoding.default_external
 => #<Encoding:UTF-8>

Why is this still so difficult in Ruby?

Answer 1

Usually you set encoding with # coding: UTF-8 for a file.

In case of irb it might be necessary to set it in advance and explicitly:

irb -E UTF-8:UTF-8

This will set both internal and external encoding to UTF-8 on irb.

Or additionally try

irb -U

which sets the internal encoding to UTF-8.

Answer 2

I don't know how to solve the problem but the sure thing is this is an irb only thing, I noticed many times irb has its own unique of dealing with user's inputs (it may even well be a limitation in readline) and it only works well with some characters.

You can do a simple test to check that, create a new rb file with:

# encoding: utf-8
puts "test: Ü"

and execute it, does it works ?

While it is still a nuisance, it is not a big enough problem for me until now to bother really looking for a solution.