ruby oracle oci8 UTF8 corruption

I have a small script oci1.rb:

require 'oci8' 
conn = OCI8.new("test","test","test_db") 
File.open("out.txt","wb") do |out| 
  tabs = conn.exec('SELECT * from test_utf8') do |r| 
     out.write(r.join(',')) 
     out.write("\n") 
  end 
end 
conn.logoff

that runs perfectly on windows producing from my test_db:

polish,łóśżć 
russsian,фывафыва 
german,äöü 

when I run exactly the same on my linux box:

polish,loszc 
russsian,???????? 
german,aou 

I tested then a small script that reads and writes UTF8 on linux to be sure my linux terminal can display UTF8
(read_write_utf8.rb):

File.open("utf8_out.txt","wb") do |out| 
  File.open("utf8.txt","r").each do |line| 
    out.write(line) 
  end 
end 

and that works good!

chris@emeadb:~/work/ruby/oci$ ruby read_write_utf8.rb 
chris@emeadb:~/work/ruby/oci$ cat utf8.txt 
polish,łóśżć 
russsian,фывафыва 
german,äöü 
chris@emeadb:~/work/ruby/oci$ cat utf8_out.txt 
polish,łóśżć 
russsian,фывафыва 
german,äöü 

Finally the issue was with my NLS_LANG variable that was not set in the Linux box on the account I used for running the script.

I tried first to set it up in the ruby script itself:

ENV['NLS_LANG']='AMERICAN_AMERICA.UTF8'

that did not work.

the solution was to set it in the shell.

export NLS_LANG=AMERICAN_AMERICA.UTF8

you can set it in your .bashrc (depending on the shell you use) to make it default for the account.