如何在os x或ubuntu下安装最新的ruby

os x下基本上可以安装到比较新的ruby，首先先安装rvm，然后用rvm list known看当前可供安装的ruby的版本，不过这也不是绝对的，比如在我的os x 10.9上，命令返回如下：

# MRI Rubies
[ruby-]1.8.6[-p420]
[ruby-]1.8.7[-p374]
[ruby-]1.9.1[-p431]
[ruby-]1.9.2[-p320]
[ruby-]1.9.3[-p484]
[ruby-]2.0.0-p195
[ruby-]2.0.0[-p353]
[ruby-]2.1.0
[ruby-]2.1.0-head
ruby-head

可以看到最新的版本为2.1.0，为了确认这点，我们用rvm mount命令看一下：

You can specify the full url to the binaries:

    rvm mount -r https://rvm.io/binaries/ubuntu/12.04/x86_64/ruby-1.9.3-p194.tar.bz2

bingo！我们到https://rvm.io/binaries下看看有神马好东东：

Index of /binaries/

../
amazon/                                            07-Aug-2013 08:41       -
arch/                                              24-Feb-2013 14:47       -
centos/                                            06-Jun-2014 22:01       -
debian/                                            06-Jun-2014 23:32       -
experimental/                                      10-Nov-2013 18:28       -
fedora/                                            07-Jun-2014 07:29       -
opensuse/                                          24-Mar-2014 04:51       -
osx/                                               31-May-2014 00:52       -
ubuntu/

自然是进入osx目录，最终我们看见了2.1.1,我们只需mount它的路径即可:

rvm mount -r https://.../ruby-2.1.1.tar.bz2

然后rvm就会下载然后自动安装，完毕后我们再将其设置为当前版本：

rvm use ruby-2.1.1

你也可以设置为默认版本:

rvm --default use ruby-2.1.1

最后我们还可以安装该版本ruby的rdoc文档以便ri查询：

rvm docs generate

然后测试一下 ri Array:

= Array < Object

------------------------------------------------------------------------------
= Includes:
Enumerable (from ruby site)

(from ruby site)
------------------------------------------------------------------------------
Arrays are ordered, integer-indexed collections of any object.

Array indexing starts at 0, as in C or Java.  A negative index is assumed to
be relative to the end of the array---that is, an index of -1 indicates the
last element of the array, -2 is the next to last element in the array, and so
on.

== Creating Arrays

A new array can be created by using the literal constructor [].  Arrays can
contain different types of objects.  For example, the array below contains an
Integer, a String and a Float:

  ary = [1, "two", 3.0] #=> [1, "two", 3.0]

An array can also be created by explicitly calling Array.new with zero, one
:

有鸟，打完收工！！！

在其他linux下安装最新ruby版本与此类似，不过最后一步貌似无法完成，是rubygem服务器的问题吗？待查！