How to update Ruby Version 2.0.0 to the latest version in Mac OSX Yosemite?

Open your terminal and run

curl -sSL https://raw.githubusercontent.com/rvm/rvm/master/binscripts/rvm-installer | bash -s stable

When this is complete, you need to restart your terminal for the rvm command to work.

Now, run rvm list known

This shows the list of versions of the ruby.

Now, run rvm install ruby@latest to get the latest ruby version.

If you type ruby -v in the terminal, you should see ruby X.X.X.

If it still shows you ruby 2.0., run rvm use ruby-X.X.X --default.

Prerequisites for windows 10:

• C compiler. You can use http://www.mingw.org/
• make command available otherwise it will complain that "bash: make: command not found". You can install it by running mingw-get install msys-make
• Add "C:\MinGW\msys\1.0\bin" and "C:\MinGW\bin" to your path enviroment variable

Brew only solution

Update:

From the comments (kudos to Maksim Luzik), I haven't tested but seems like a more elegant solution:

After installing ruby through brew, run following command to update the links to the latest ruby installation: brew link --overwrite ruby

Original answer:

Late to the party, but using brew is enough. It's not necessary to install rvm and for me it just complicated things.

By brew install ruby you're actually installing the latest (currently v2.4.0). However, your path finds 2.0.0 first. To avoid this just change precedence (source). I did this by changing ~/.profile and setting:

export PATH=/usr/local/bin:$PATH

After this I found that bundler gem was still using version 2.0.0, just install it again: gem install bundler

I recommend rbenv* https://github.com/rbenv/rbenv

* If this meets your criteria: https://github.com/rbenv/rbenv/wiki/Why-rbenv?:

rbenv does…

• Provide support for specifying application-specific Ruby versions.
• Let you change the global Ruby version on a per-user basis.
• Allow you to override the Ruby version with an environment variable.

In contrast with RVM, rbenv does not…

• Need to be loaded into your shell. Instead, rbenv's shim approach works by adding a directory to your $PATH.
• Override shell commands like cd or require prompt hacks. That's dangerous and error-prone.
• Have a configuration file. There's nothing to configure except which version of Ruby you want to use.
• Install Ruby. You can build and install Ruby yourself, or use ruby-build to automate the process.
• Manage gemsets. Bundler is a better way to manage application dependencies. If you have projects that are not yet using Bundler you can install the rbenv-gemset plugin.
• Require changes to Ruby libraries for compatibility. The simplicity of rbenv means as long as it's in your $PATH, nothing else needs to know about it.

INSTALLATION

Install Homebrew http://brew.sh

Then:

$ brew update
$ brew install rbenv 
$ brew install rbenv ruby-build

# Add rbenv to bash so that it loads every time you open a terminal
echo 'if which rbenv > /dev/null; then eval "$(rbenv init -)"; fi' >> ~/.bash_profile
source ~/.bash_profile

UPDATE
There's one additional step after brew install rbenv Run rbenv init and add one line to .bash_profile as it states. After that reopen your terminal window […] SGI Sep 30 at 12:01 —https://stackoverflow.com/users/119770

$ rbenv install --list
Available versions:
 1.8.5-p113
 1.8.5-p114
 […]
 2.3.1
 2.4.0-dev
 jruby-1.5.6
 […]
$ rbenv install 2.3.1
[…]

Set the global version:

$ rbenv global 2.3.1
$ ruby -v
ruby 2.3.1p112 (2016-04-26 revision 54768) [x86_64-darwin15]

Set the local version of your repo by adding .ruby-version to your repo's root dir:

$ cd ~/whatevs/projects/new_repo
$ echo "2.3.1" > .ruby-version

For MacOS visit this link

Open Terminal:

sudo gem update --system 

It works!

Fast way to upgrade ruby to v2.4+

brew upgrade ruby

or

sudo gem update --system