greeklish_iso843 
A Ruby library that converts Greek text to Greeklish, conforming to the ISO 843 standard (based on the Greek standard ELOT 743 or ΕΛΟΤ 743) used by the Greek state.
Demo
An online service that uses this Gem is available at https://greeklish.xyz
Installation
As a Gem:
gem install greeklish_iso843
Use
Require the library in your code:
require 'greeklish_iso843'
Then you can use it to convert text:
GreeklishIso843::GreekText.to_greeklish("Μπάμπης") # => "Bampis"
GreeklishIso843::GreekText.to_greeklish("Άγγελος") # => "Angelos"
GreeklishIso843::GreekText.to_greeklish("Ευάγγελος") # => "Evangelos"
GreeklishIso843::GreekText.to_greeklish("ξεσκεπάζω την ψυχοφθόρα σας βδελυγμία") # => "xeskepazo tin psychofthora sas vdelygmia"
Alternatively, you can require the String core extension for more convenience:
require 'greeklish_iso843/core_ext/string'
Then you can use it to convert text:
"Μπάμπης".to_greeklish # => "Bampis"
There's also a command line utility that accepts Greek text from the standard input and prints the corresponding Greeklish text to the standard output:
$ greeklish_iso843
Μπάμπης
^D
Bampis
$
Note: ^D represents the EOF (End Of File) character, emitted with Ctrl-D.
Tests
You can run the tests with rake test or rake test TESTOPTS='-v' for a more
verbose output.
Acknowledgements
This library was initially based on an official, buggy implementation in JavaScript by the Hellenic Police.