nice guide... i tried it with sucess on ubuntu 18 !

DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=18.04
DISTRIB_CODENAME=bionic
DISTRIB_DESCRIPTION="Ubuntu Bionic Beaver (development branch)"

rbenv version
2.5.0 (set by /home/marcelo/.rbenv/version)

git --version
git version 2.15.1

ruby -v
ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-linux]

rails -v
Rails 5.1.4

psql --version
psql (PostgreSQL) 9.5.10

Worked for me on Ubuntu 18.04

Getting ruby and rails to run on Ubuntu 18.04LTS is certainly not easy.
Background: I'm not a ruby programmer. I'm just trying to get my redmine site up and running again after upgrading to 18.04.

First, I tried installing redmine directly from Ubuntu. That failed miserably. (sorry I don't remember everything that happened. But I believe it had to do with not finding an openssl library that was clearly present). I had hopes this would just install all of the proper dependencies with no errors.

Then, i tried following the instructions on redmine.com, which suggests not using the packaged install. That didn't work very well either. At one point, I ended up at the same openssl nonsense.

Now, I tried these instructions, and ruby seems to install OK with rbenv (although I don't really like it installing into a hidden directory in my home directory, with no apparent option to select the install directory). But rails falls flat at the nodejs install. I get: "rvm: command not found".
I found rvm in /usr/share/rvm/bin, but adding this to my path in .bashrc doesn't fix it.

I don't remember ruby/rails being this much of a pain under 12.04. Is there an easier way?

https://github.com/rbenv/ruby-build/issues/834

There's an issue installing older versions of ruby (<2.4) with rbenv.

Need to use:

sudo apt install libssl1.0-dev

I use Ubuntu 18.04 and PostgreSQL 11 doesn't work. It was unable to locate package, but 10 works.

I have the follwing error :
$ rake db:seed

rake aborted!
Mysql2::Error::ConnectionError: Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (13)

Tasks: TOP => db:abort_if_pending_migrations
(See full trace by running task with --trace)

Question: Why are we cloning from git to install rbenv and ruby-build instead of just installing with apt?

I believe the instructions for installing postgres 11 are outdated; I had to manually create a pgdg.list file as per official site instructions. Similarly, before creating my username I had to start the service manually