gem install mysql on linux
It might be a problem, an “old” well-known issue…
sudo gem install mysql
might return an error like:
ERROR: While executing gem ... (Gem::Installer::ExtensionBuildError)
ERROR: Failed to build gem native extension.
Well, this is cause you need the -dev environment of mysql. Too easy to think that it could be mysql-dev, no! just try
apt-get install libmysqlclient15-dev
It will works!