Install the Oniguruma gem

If you get this:

Installing typhoeus (0.3.3) with native extensions
/usr/local/lib/site_ruby/1.8/rubygems/installer.rb:483:in `build_extensions': ERROR: Failed to build gem native extension. (Gem::Installer::ExtensionBuildError)

/usr/bin/rub...

You need to install the following packages before you can build the Paperclip gem:

sudo apt-get install imagemagick librmagick-ruby

You need to install the following packages before you can build the Nokogiri gem:

sudo apt-get install libxml2-dev libxslt1-dev

sudo gem install zip
git clone git://github.com/rtomayko/date-performance.git
cd date-performance
rake package:build
cd dist
sudo gem install --no-ri --no-rdoc date-performance-0.4.7.gem

sudo apt-get install sqlite3 libsqlite3-dev
sudo gem install sqlite3-ruby

So you're getting this failure when running bundle install on an older project:

Your Gemfile.lock is corrupt. The following gems are missing from the DEPENDENCIES section: 'archive-tar-minitar' 'hoe' 'rcov'

This happens when you ar...

Recent Bundler (1.16.1) started complaining about missing dependencies in the Gemfile. This is due to a stricter handling of specifications (see attached link).

The error message looks like this:

Downloading example-gem-1.2.3 revealed depend...

Installing gems on a server that has no access to the internet (especially rubygems.org) requires to bundle the gems into the repository itself. This requires to adjust the bundle config in the repository.

1. Execute the following commands to c...

So you got this error, even though your Gemfile bundles mysql2:

!!! Missing the mysql2 gem. Add it to your Gemfile: gem 'mysql2'

or

Please install the mysql adapter: `gem install activerecord-mysql-adapter` (mysql is not par...

In case https://www.rubydoc.info/ is to slow or offline, you can also read a gem documentation offline.

Start a server with gem server and go to http://0.0.0.0:8808/. Here you will find a list of all installed gems and it is possible to nav...