If you find that a JRuby release does not have the latest time zone data, and if you think this is important, you can build JRuby from source with the most up-to-date Olson database.

Note that MRI relies on the underlying OS to provide date and time information.

Environment in which ftp Ant task can run. This means that you have Apache Commons Net installed and available for your JVM (and ant).

1. Move to the root of the JRuby source.
2. Optionally edit default.build.properties and set tzdata.latest.version to the version you want. (If you don't know what you need, you can leave the default in. We try to keep this value fairly up-to-date.)
3. Run ant clean compile-tzdata jar.
4. Confirm that you have the new version of tzdata:

./bin/jruby -rrbconfig -e 'p RbConfig::CONFIG["tzdata.version"]'
"2012b"