How to Update Ruby Versions on Linux with rbenv#

Update ruby-build as an rbenv plugin#

cd ~/.rbenv/plugins/ruby-build

git pull

Find Available versions#

rbenv install --list

Install version#

rbenv install 2.1.5

Set the ruby version to use globally#

rbenv global 2.1.5

Check ruby version#

ruby -v

Note: You need to Reinstall bundler for each version of Ruby you use#

Errors:#

./libffi-3.2.1/.libs/libffi.a: could not read symbols: Bad value

Solution: Install libffi-dev#

sudo apt-get install libffi-dev

Sources: makandracards digitalocean