Today I had to build a Jekyll pipeline so I needed a clean way to install native ruby and gems.

Ruby is a dynamic, object-oriented programming language.

We are using RVM, which stands for Ruby Version Manager, which makes easier to install Ruby on Linux platform. RVM is also helpful for managing multiple version of Ruby without conflicting, and we can switch system to any version of Ruby using a single command.

Disclaimer: The following software to be installed under a specific user not root!

Install rvm (Ruby Version Manager).

Note: unlike rubygems and bundler(package managers), rvm is a version manager

Get the gpg keys.

gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB

Fetch the script and run it in bash.

\curl -sSL https://get.rvm.io | bash
source ~/.rvm/scripts/rvm
rvm -v

Helpful. Check what versions are available rvm list known

Install ruby

rvm install ruby

note, the command will install all dependencies: sudo yum install curl gpg gcc gcc-c++ make patch autoconf automake bison libffi-devel libtool patch readline-devel sqlite-devel zlib-devel openssl-devel

Or install a specific version rvm install 2.5.7. Confirm the version: ruby -v Or specify another version rvm use 2.5.6 --default

Check for troubles:

rvm requirements
Warning! PATH is not properly set up, /home/git/.rvm/gems/ruby-2.7.1/bin is not at first place.
         Usually this is caused by shell initialization files. Search for PATH=... entries.
         You can also re-add RVM to your profile by running: rvm get stable --auto-dotfiles
         To fix it temporarily in this shell session run: rvm use ruby-2.7.1
         To ignore this error add rvm_silence_path_mismatch_check_flag=1 to your ~/.rvmrc file.
Checking requirements for centos.
Requirements installation successful.

If the above error occurs run rvm reset

Update the system environment variables

source /etc/profile.d/rvm.sh

Add current user (spokane) to the rvm group

sudo usermod -aG rvm spokane

rvm reload

Note RVM reloaded! Yep!

You need that as dependencies for jekyll

rubygems

Rubygems is a medium level package manager: Ruby, at its lowest level, doesn’t really have “libraries” built in. It has the ability to “load” or “require” a file, and it has $LOAD_PATH, an array of paths to check when you ask for a filename

Install dependencies (around 6M)

It will install curl gpg gcc gcc-c++ make patch autoconf automake bison libffi-devel libtool patch readline-devel sqlite-devel zlib-devel openssl-devel

sudo dnf install ruby-devel @development-tools

sudo dnf install rubygems

Make sure you’ll have latest lists sudo gem update Then check the system overall: sudo gem update --system

It is best to avoid installing Ruby Gems as the root user.

Therefore, we need to set up a gem installation directory for your user account.

The following commands will add environment variables to your ~/.bashrc file to configure the gem installation path.

echo '# Install Ruby Gems to ~/gems' >> ~/.bashrc
echo 'export GEM_HOME="$HOME/gems"' >> ~/.bashrc
echo 'export PATH="$HOME/gems/bin:$PATH"' >> ~/.bashrc
source ~/.bashrc

NOTE: In order to have a jekyll pipeline these steps needs to be run on both local and on the server

Interactive Ruby

Open up a shell and type irb and hit enter.

irb(main):003:0> 3+2
=> 5

irb(main):003:0> puts "Hello World"
Hello World
=> nil

Run your first program

$ vim hello.rb

then type inside

puts "Hello world, this is a message targeting all of you."
puts "Input your name please: "
inp = gets
puts "Thanks " + inp + " for providing your name. We will send this name to aliens soon ;)"

run it

ruby hello.rb

Ruby functions

def print_hi(name)
  puts "Hi, #{name}"
end
print_hi('Yuri')
#=> prints 'Hi, Yuri' to STDOUT.