gettext for Ruby

Gem Version Build Status

NOTE: Gettext gem 3.0.0 removed many deprecated APIs and improves internal APIs. We want to keep backward compatibility as much as possible but some existing codes may be broken by gettext gem API change. If your code breaks by gettext gem 3.0.0, please report your problem. We will fix the problem and release a new version. is the official gettext gem repository. It is moved from . Mutoh agreed with the move.

Gettext gem is a pure Ruby Localization(L10n) library and tool which is modeled after the GNU gettext package.

This library was called as "Ruby-GetText-Package". Since 2.3.0, this library is called just "gettext". You can call this library as "gettext gem" or "Ruby gettext" to distinguish from GNU gettext.

This library translates original messages to localized messages using client-side locale information(environment variable or CGI variable).

The tools for developers support creating, useing, and modifying localized message files(message catalogs).

Rails support has been removed.

Table of Contents


  • Translate singular/plural messages with simple APIs (similar to GNU gettext)
  • Thread safety. Message resources are shared from all threads, but returns translated messages of the current thread's locale.
  • Tools to find message IDs
    • Extract message IDs to po-files using rxgettext from
    • ruby scripts
    • glade-2 XML file (.glade)
    • ERB file (.rhtml, .erb)
    • Anything (with your own parsers)
    • The po-files are compatible with GNU gettext.
    • rmsgfmt creates a mo-file from a po-file. The mo-file is compatible with GNU gettext (msgfmt).
    • Using rxgettext/rmsgfmt as Rake tasks
  • textdomain's scope is adapt to ruby class/module mechanism.
    • A class/module can have plural textdomains.
    • a message is looked up in its class/module and ancestors.
  • CGI support (gettext/cgi)
    • Locale is retrieved from client informations using Ruby-Locale. (HTTP_ACCEPT_LANGUAGE, HTTP_ACCEPT_CHARSET, QUERY_STRING (lang), Cookies (lang)).


For development:

  • Racc 1.4.3 or later (for compiling src/rmsgfmt.ry only)


Uninstall old gettext if exists. (You need to do this when updating 1.93.0 -> 2.0.1)

# sudo/su on POSIX system
gem uninstall gettext


# sudo/su on POSIX system
gem install gettext

Download tar-ball

# De-Compress archive and enter its top directory.
# sudo/su on POSIX system
ruby setup.rb

You can also install files in your favorite directory by supplying setup.rb some options. Try ruby setup.rb --help.



_(): basic translation method

Translates the message.


The gettext methods come in 3 combinable flavors:

n_(): pluralized

Returns singular or plural form, depending on how many you have.

n_("Apple", "%{num} Apples", 3)
n_(["Apple", "%{num} Apples"], 3)

p_(): context aware

A context is a prefix to your translation, usefull when one word has different meanings, depending on its context.

p_("Printer","Open") <=> p_("File","Open")
is the same as s_("Printer|Open")  <=> s_("File|Open")

s_(): without context

If a translation could not be found, return the msgid without context.

s_("Printer|Open") => "Öffnen" #translation found
s_("Printer|Open") => "Open"   #translation not found


np_("Fruit", "Apple", "%{num} Apples", 3)
ns_("Fruit|Apple","%{num} Apples", 3)

np_(["Fruit","Apple","%{num} Apples"], 3)
ns_(["Fruit|Apple","%{num} Apples"], 3)

N_(), Nn_(): makes dynamic translation messages readable for the gettext parser

_(fruit) cannot be understood by the gettext parser. To help the parser find all your translations, you can add fruit = N_("Apple") which does not translate, but tells the parser: "Apple" needs translation.

fruit = N_("Apple")   # same as fruit = "Apple"
_(fruit)              # does a normal translation

fruits = Nn_("Apple", "%{num} Apples")
n_(fruits, 3)

Bind textdomains to the classes

A textdomain has a translation file in each language. A module/class can have multi textdomains. This means the libraries/applications can have their own textdomains.

class Foo
  include GetText
  bindtextdomain "your_app_domain_name"

class Book
  include GetText
  bindtextdomain "general"
  bindtextdomain "book"


If you need to set the locale by yourself, then use:

GetText.locale = "en_US" # translate into english from now on
GetText.locale # => en_US


include GetText
set_locale "en_US"

For more details and options, have a look at the samples folder or consult the tutorial.


This program is licenced under the same licence as Ruby (See doc/text/ruby-license.txt) or LGPL (Lesser General Public License: doc/text/lgpl-3.0.txt or


Copyright (C) 2001-2009 Masao Mutoh <mutoh at>
Copyright (C) 2001,2002 Masahiro Sakai <s01397ms at>


Copyright (C) 2001-2009 Masao Mutoh <mutoh at>
Copyright (C) 2001,2002 Masahiro Sakai <s01397ms at>


Copyright (C) 2001-2009 Masao Mutoh <mutoh at>
Copyright (C) 2001,2002 Yasushi Shoji <yashi at>


Copyright (C) 2001-2009 Masao Mutoh <mutoh at>


Language Translator Status
Bosnian (bs) Sanjin Sehic <saserr at> 1.90.0 (old)
Bulgarian (bg) Sava Chankov <sava.chankov at> 2.0.1
Catalan (ca) Ramon Salvadó <rsalvado at> 2.0.1
Chinese (Simplified)(zh_CN) Yang Bob < at> (current)
Yingfeng <blogyingfeng at>
Chinese (Traditional)(zh_TW) Yang Bob < at> (current)
Lin Chung-Yi <xmarsh at>
Croatian (hr) Sanjin Sehic <saserr at> 1.90.0 (old)
Czech (cs) Karel Miarka <kajism at> 1.9.0 (old)
Dutch (nl) Menno Jonkers <ruby-gettext at> 1.90.0 (old)
English (default) 2.1.0
Esperanto (eo) Malte Milatz <malte at> 2.0.1
Estonian (et) Erkki Eilonen <erkki at> 2.0.1
French (fr) Vincent Isambart <vincent.isambart at> (current)
David Sulc <davidsulc at>
Laurent Sansonetti <laurent.sansonetti at>
German (de) Patrick Lenz <patrick at> (current)
Detlef Reichl <detlef.reichl at>
Sven Herzberg <herzi at>
Sascha Ebach <se at>
Greek (el) Vassilis Rizopoulos <damphyr at> 2.0.1
Hungarian (hu) Tamás Tompa <tompata at> 2.0.1
Italian (it) Marco Lazzeri <marco.lazzeri at>
Gabriele Renzi <surrender_it at>
1.6.0 (old)
Japanese (ja) Masao Mutoh <mutomasa at> 2.1.0
Korean (ko) Gyoung-Yoon Noh <nohmad at> 1.9.0 (old)
Latvian (lv) Aivars Akots <aivars.akots at> 2.0.1
Norwegian (nb) Runar Ingebrigtsen <runar at> 2.0.1
Portuguese (Brazil)(pt_BR) Antonio S. de A. Terceiro <terceiro at> (current)
Joao Pedrosa <joaopedrosa at>
Russian (ru) Yuri Kozlov <kozlov.y at> 2.0.1
Serbian (sr) Slobodan Paunović <slobodan.paunovic at> 2.0.1
Spanish (es) David Espada <davinci at> (current)
David Moreno Garza <damog at>
Swedish (sv) Nikolai Weibull <mailing-lists.ruby-talk at> 0.8.0 (very old)
Ukrainian (uk) Alex Rootoff <rootoff at> 2.0.1
Vietnamese (vi) Ngoc Dao Thanh <ngocdaothanh at> 2.0.1


  • Kouhei Sutou <>

Old maintainer

  • Masao Mutoh <mutomasa at>