Setting up a fresh Lion for Ruby development / by Paulo Fierro

Update (July 30, 2012):

If you've upgraded to Mountain Lion the below instructions still work. Once complete you should check out this guide. It contains a tip on installing gcc via brew in order to avoid using CLANG which can result in occasional errors when installing/updating gems.

--- End of update ---

A few weeks back I decided to take the plunge and wipe my machine and set it up from scratch. The main reason being I was running out of space on my SSD and I just wanted to see what a fresh Lion install would be like.

Let me tell you, its FAST! Totally worth it. It did take me some time to find the right resources and shave some yaks so this is more of a guide for future-me to save some time. If you do carry on reading from this point I assume you know what you're doing :)

So now that everything is wiped and fresh and new (backed up of course) the main task is setting up ye old dev environment. Lets start at the beginning.


Head over to the Mac App Store and download Xcode. Once you install it you'll find that it no longer lives in /Developer. Its been moved to /Applications and its command line tools are no longer in the $PATH on the command line.

We don't have to add them ourselves, simply start up Xcode, go to Preferences and then Downloads > Components. Click on the "Install" button next to "Command Line Tools".


If you're deploying stuff on Heroku, grab the toolbelt here.


Previously I was using MacPorts, but after hearing so many great things about Homebrew I took the plunge. Its simply a great package manager and you can download it here. For example, OS X doesn't ship with wget, so to install it you can simply run the following on the command line:

brew install wget

Done. Moving on.


RVM is a command-line tool which allows you to easily install, manage, and work with multiple ruby environments from interpreters to sets of gems.

What it says on the tin. It allows you to easily install multiple versions of Ruby on your system. It also allows you create gem sets and swap between them. To install:

bash -s stable < <(curl -s


source ~/.rvm/scripts/rvm

Now we're ready to install Ruby! The only problem is that with Xcode 4 the provided compiler (gcc) is LLVM based and not yet fully supported by Ruby and gems. Now before you go hunting for an older gcc (which I did) its not necessary.

To install Ruby 1.9.2 (which is required for Heroku) enter:

rvm install 1.9.2 --with-gcc=clang

When that is done, lets check what version of Ruby we have set as the system default:

ruby --version

Mine said Ruby 1.8.7. Lets set 1.9.2 to be default:

rvm use 1.9.2 --default

If you run ruby --version it should now say 1.9.2. If you ever want to go back to the system default simply enter rvm system. So now we have an easy way of swapping Ruby versions and you can read more about it here.

Sublime Text

Sublime Text is my favourite editor of all time. Get it here. Read some great tips and tricks here.


Previously I was using MAMP. However I had an issue installing the do_mysql gem which is required for dm-mysql-adapter I was using with Datamapper.

Long story short I found the easiest thing to do was install mysql via brew instead of using MAMP. So to start off:

brew install mysql

Next to configure the installation (all one line):

mysql_install_db --verbose --basedir="$(brew --prefix mysql)" --datadir=/usr/local/var/mysql --tmpdir=/tmp

To get it to run on startup, first we have to create the directory if it doesn't exist:

mkdir -p ~/Library/LaunchAgents

Then we copy the mysql.plist over (the version number may have changed when you're reading this):

cp /usr/local/Cellar/mysql/5.5.20/homebrew.mxcl.mysql.plist ~/Library/LaunchAgents/

Then we tell launchctl to load it on startup:

launchctl load -w ~/Library/LaunchAgents/homebrew.mxcl.mysql.plist

Now to set the password:

mysqladmin -u root password {new-password}

Phew! Ok, now mysql is installed and running on port 3306. To create your first database simply enter:

mysqladmin -u root -p create {your-database-name}

And some gem love...

Finally I recommend using bundler for gem management, foreman to run your app (especially if you're on Heroku), rerun to rerun your app when something changes, datamapper for ORM and sinatra for happiness.

Good luck!