Ruby

https://www.ruby-lang.org/en/

Dynamically typed open-source programming language known for its simplicity, flexibility, and focus on developer happiness.

Not my main language but it's an easy language to pick up so I've written a few bits and pieces over the years eg. check_puppet.rb.

• Popularity Over the Years
• Poignant Guide to Ruby
• IRB
  • JIRB
• Gem
  • Install Gems
  • Interesting Gems
  • List Installed Gems
  • Install from Custom Gem Server
• rbenv
  • rbenv install
  • rbenv install ruby versions
  • rbenv local
  • rbenv global
  • rbenv shell
  • rbenv gem
• RVM - Ruby Version Manager
  • RVM Install
  • RVM Usage
• Code
• Linting
  • Rubocop
• JRuby
  • Rubinius
  • Ludicrous
• Ruby IDEs
  • RubyMine
  • Alternatives
• Meme
  • Porting Your Language to the JVM

Popularity Over the Years

IMO was at peak popularity in the late 2000s when Puppet was the big thing (Puppet was written in Ruby) and was the first widely used configuration language (CFengine wasn't as widely used).

Update: a quick Google found this article showing Ruby actually peaked in the mid 2000s rather than the late 2000s. I probably should have made more notes here at that time...

Poignant Guide to Ruby

A popular source for learning Ruby.

https://poignant.guide/book/

http://www.rubyinside.com/media/poignant-guide.pdf

IRB

Interactive Ruby interpreter.

(if you need to install the irb Gem see next section)

Start the irb interactive ruby interpreter:

irb

JIRB

JRuby interactive Ruby interpreter.

Start the jirb interactive ruby interpreter:

jirb

GUI irb using swing:

jruby -S jirb_swing

java_import java.lang.System
version = System.getProperties["java.runtime.version"]

Gem

Install Gems

gem install "$name"

Install the mdl gem for markdown linting (used heavily to check the docs in this repo):

gem install mdl

Run mdl to check an .md file:

mdl README.md

Interesting Gems

• dotenv - load .env or .envrc files
• irb - Interactive Ruby interpreter
• mdl - Markdown lint
• lolcat - turns text into rainbow colours
• gitlab - GitLab CLI
• fastlane - see Fastlane doc
• jgrep
• httparty
• gist
• kramdown

List Installed Gems

gem list

Configure gem command to install gems to user writable $HOME/.gem/ruby/<version>/gems/ directory:

In $HOME/.gemrc:

gem: --user-install

gem install then installs to ~/.gem/ruby/<version>/gems.

Then make sure to add $HOME/.gem/ruby/<version>/bin to $PATH environment to be able to run commands installed by gems:

gem env

Runs server on http://localhost:8808 to show installed gems:

gem server

gem install ruby-debug

gem install cheat

Install from Custom Gem Server

gem install --source http://server

rbenv

:octocat: rbenv/rbenv

:octocat: rbenv/ruby-build

rbenv install

Installs to ~/rbenv (RBENV_ROOT):

brew install rbenv

Adds to ~/.bash_profile:

rbenv init

Open a new login shell:

bash -l

or source:

source ~/.bash_profile

rbenv install ruby versions

List installed ruby versions:

rbenv versions

* system

List latest stable versions:

rbenv install -l

List all local versions:

rbenv install -L

Install a Ruby version:

rbenv install 3.4.1

rbenv local

Set the local Ruby version for this directory (creates a .ruby-version file):

rbenv local 3.4.1

Show the local configured version:

rbenv local

Undo the local ruby setting:

rbenv local --unset

rbenv global

Set the global ruby version by setting ~/.rbenv/version:

rbenv global 3.4.1

rbenv shell

Set the Ruby version in the local shell only with environment variable RBENV_VERSION:

rbenv shell 3.4.1

which irb

/Users/hari/.rbenv/shims/irb

rbenv which irb

/Users/hari/.rbenv/versions/3.4.1/bin/irb

rbenv gem

Check your gem is using the rbenv ruby version:

gem env home

/Users/hari/.rbenv/versions/3.4.1/lib/ruby/gems/3.4.0

rbenv which gem

/Users/hari/.rbenv/versions/3.4.1/bin/gem

Then gem install as usual:

gem install bundler

rbenv versions

rbenv versions
  system
* 3.4.1 (set by /Users/hari/github/.../.ruby-version)

rbenv version

rbenv version
3.4.1 (set by /Users/hari/github/.../.ruby-version)

RVM - Ruby Version Manager

https://rvm.io/

Installs multiple Ruby environments, interpreters and gem commands under

Like VirtualEnv in Python - multiple ruby environments, interpreters and gems

RVM Install

Install GPG Keys:

gpg2 --keyserver keyserver.ubuntu.com \
     --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 \
                 7D2BAF1CF37B13E2069D6956105BD0E739499BDB

On Mac, had to do this instead:

gpg --keyserver hkps://keys.openpgp.org \
    --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 \
                7D2BAF1CF37B13E2069D6956105BD0E739499BDB

Prompts to import GPG keys if you skipped the step above:

curl -sSL https://get.rvm.io | bash -s stable

or with Ruby-on-Rail (compiles, takes ages):

curl -sSL https://get.rvm.io | bash -s stable --rails

You will likely get a warning to remove the user gem setting from $HOME/.gemrc as it'll clash with RVM:

In $HOME/.gemrc, remove:

gem: --user-install

RVM Usage

:octocat: rvm/rvm

https://rvm.io/rvm/basics

See available interpreters:

rvm list known

Install a recent Ruby interpreter:

rvm install ruby

Further help:

rvm help

Code

Code	Description
foo	local variable (default: NameError: undefined local variable exception)
$foo	global variable (default: nil)
@foo	instance variable (default: nil)
@@foo	class variable (default: NameError exception)
^[A-Z]...	constant (default: NameError exception)

puts object.inspect

object.to_yaml

Path to code modules:

$LOAD_PATH

Linting

Rubocop

:octocat: rubocop/rubocop

gem install rubocop

rubocop

Auto-correct the file(s) at your own peril:

(make sure you git commit before running this to see the changes / revert)

rubocop -a

will annoyingly space all:

#comment_out_code

lines to

# comment_out_code

but where they are opening blocks it won't indent the block contents to stay aligned by 2 space indents:

# lane :build do |options|
#  puts "Building version #{options[:version]}"
# end

JRuby

Run Ruby on the Java JVM with full access to Java libraries.

See also Jython.

Personally, I much prefer Groovy.

Use Java library jar:

require '/path/to/my.jar'

Not needed in jirb (JRuby's interactive interpreter):

require 'java'

import java.lang.System

Newer safer way to import from Java:

java_import java.lang.System

version = System.getProperties["java.runtime.version"]

this does equiv of: import org.xxx.yyy and includes *:

include_package "org.xxx.yyy"

Rubinius

:octocat: rubinius/rubinius

JIT for Ruby

Ludicrous

http://rubystuff.org/ludicrous/

JIT for Ruby

Experimental last I checked and performance roughly on par with YARV (Yet Another Ruby VM bytecode interpreter) which has since been merged into official Ruby 1.9 interpreter 2007.

Ruby IDEs

RubyMine

https://www.jetbrains.com/ruby/

Ruby-specific IDE by Jebrains, based off IntelliJ IDEA.

Unfortuntely, this is proprietary paid for only and doesn't have a free version like PyCharm or main IntelliJ.

Alternatives

VS Code, Sublime or Gleany.

See Editors & IDEs page.

Meme

Porting Your Language to the JVM

Ported from private Knowledge Base page 2012+