Can't install MySQL gem

On Ubuntu/Debian and other distributions using aptitude:

sudo apt-get install libmysql-ruby libmysqlclient-dev

If the above command doesn't work because

libmysql-ruby

cannot be found, the following should be sufficient:

sudo apt-get install libmysqlclient-dev

On Red Hat/CentOS and other distributions using yum:

sudo yum install mysql-devel

On Mac OS X with Homebrew:

brew install mysql