sudo apt-get install ruby1.9

should do the trick.

You can find what libraries are available to install by

apt-cache search <your search term>

So I just did apt-cache search ruby | grep 9 to find it.

You'll probably need to invoke the new Ruby as ruby1.9, because Ubuntu will probably default to 1.8 if you just type ruby.

Why not use ruby 2.3 which is available in the repositories for 16.04 and 17.10 with

sudo apt update

After the update is finished run:

sudo apt-get install ruby2.3 ruby2.3-dev

Or try ruby 2.4 or 2.5

You can get those via the brightbox PPA

1. Add the repository and update

   sudo apt-add-repository ppa:brightbox/ruby-ng && sudo apt-get update
   

2. install

   sudo apt-get install ruby2.4
   

   or for 18.04

   sudo apt-get install ruby2.5 ruby2.5-dev
   

Information on the status of packages in the aforementioned PPA can be found on the “Brightbox” team launchpad page.

Alternatively you could try reverse hacking the error alternative path /usr/bin/ruby2.2 doesn't exist by creating it with sudo mkdir /usr/bin/ruby2.2 and trying again.

I use Ubuntu, and I've found the easiest way to install newer versions of Ruby is to use rvm.

The instructions are here: https://rvm.io/rvm/install/

Basically, it installs different versions of Ruby locally for the user and updates environment variables for Ruby and gems based on which version you decide to use.

It's this easy:

jim@schubert:~$ rvm use system
Now using system ruby.
jim@schubert:~$ ruby -v
ruby 1.8.7 (2010-08-16 patchlevel 302) [x86_64-linux]
jim@schubert:~$ gem -v
1.3.7
jim@schubert:~$ rvm use 1.9.2
Using /home/jim/.rvm/gems/ruby-1.9.2-p180
jim@schubert:~$ ruby -v
ruby 1.9.2p180 (2011-02-18 revision 30909) [x86_64-linux]
jim@schubert:~$ gem -v
1.5.2
jim@schubert:~$ 

How to get a current Ruby version without messing up your system

Do not mess with your system Ruby, but instead install a current version with either rbenv or RVM. I prefer the first, but both work fine. Note that you can only install one of those at a time.

With such a Ruby version manager, you'll never have to type sudo again to install (or uninstall) a Gem, and you can keep different versions for different projects. You can safely remove these versions again.

Please make sure to read the READMEs of those tools, at least once.

Method 1 – rbenv

rbenv is a version manager for Ruby. It allows you to install a Ruby version alongside your original system Ruby, which means you cannot mess up that one, and you can easily upgrade versions.

To install it, use the rbenv-installer. Make sure to restart your shell once it's installed, and that the rbenv function works.

Then, once rbenv is installed, run rbenv install -l. This gives you a list of available Rubies. Install your chosen one with:

rbenv install 2.5.1

Now choose this one as your default:

rbenv global 2.5.1

As soon as this is done, gem can be used to run:

gem install rails

If the above does not work, you might be missing required packages for building from source. See here for a list of packages that you might want to install. On Ubuntu, these include:

sudo apt install autoconf bison build-essential libssl-dev libyaml-dev libreadline6-dev zlib1g-dev libncurses5-dev libffi-dev libgdbm5 libgdbm-dev

Method 2 – RVM

You can also install Ruby over RVM. Here as well, you don't need to sudo anything, and you'll be able to get more recent versions of Ruby alongside the system one.

Read the installation instructions for your system.

After installation, you can install Rubies with a simple command. First, check rvm list known to get the list of installable versions. Now install your choice:

rvm install 2.5.1

Then, set it as the default Ruby version for your user:

rvm use 2.5.1 --default

Now you can install Rails over gem:

gem install rails