Question

I’ve been struggling with this for a few hours. Everything just stopped working and I can’t get it to work anymore. I’m a noob at Ruby, Ruby on Rails and the Terminal in general. This is really frustrating me so I just try to describe my problem as detailed as possible hoping someone can give me a solution.

I’m on Mac OS X Snow Leopard. I couldn’t get Rails working at all just now: Could not find gem 'rails' headaches

But after some tries of reinstalling it, it suddenly worked again. But now I just can’t get MySQL to work, and it sometimes even breaks the Rails installation again.

This is what I do:

sudo gem uninstall rails
sudo gem uninstall mysql
sudo gem uninstall mysql2

After these commands, I check the installed gems with gem list. No MySQL gem is listed anymore, but I can still see rails (2.3.5, 2.2.2, 1.2.6)
. Is this normal? Does this mean I have 3 Rails installations? It doesn’t make sense to me. Anyway, then I do this:

sudo gem clean

Which fails completely. I get a bunch of errors like this:

Attempting to uninstall fcgi-0.8.7
Unable to uninstall fcgi-0.8.7:
Gem::InstallError: cannot uninstall, check gem list -d fcgi

It doesn’t uninstall anything. At this point, I try to install everything again. I start with:

sudo gem install rails

Which succeeds (I think):

Successfully installed rails-3.0.3
Successfully installed builder-2.1.2
2 gems installed
Installing ri documentation for rails-3.0.3…
File not found: lib

Then, I update RubyGems:

sudo gem update --system
sudo gem install rubygems-update
sudo update_rubygems

Then it says I have 1.3.7 installed, so it succeeded, I think. So now I proceed with installing MySQL. I already got MySQL 5.5.8 installed on my machine. I did some research about installing MySQL on Snow Leopard, and it seems I have to use this command:

sudo env ARCHFLAGS="-arch x86_64" gem install mysql -- --with-mysql-config=/usr/local/mysql/bin/mysql_config

I get a bunch of errors like this:

No definition for time_set_neg
No definition for time_set_second_part
No definition for time_equal
No definition for error_errno

At this point, I assume I got both Rails and the MySQL gem installed, so I try to start a new project.

rails new user_group -d mysql

It works! Rails is installed correctly. Now, I try generating a model.

cd user_group
rails generate model User

It fails with this error:

Could not find gem ‘mysql2 (>= 0, runtime)’ in any of the gem sources listed in your Gemfile.
Try running bundle install.

So I try running bundle install. It installs a lot of gems. Then I try to generate my model again. I get this error:

Library/Ruby/Gems/1.8/gems/mysql2-0.2.6/lib/mysql2/mysql2.bundle: dlopen(/Library/Ruby/Gems/1.8/gems/mysql2-0.2.6/lib/mysql2/mysql2.bundle, 9): Library not loaded: libmysqlclient.16.dylib (LoadError)
Referenced from: /Library/Ruby/Gems/1.8/gems/mysql2-0.2.6/lib/mysql2/mysql2.bundle
Reason: image not found – /Library/Ruby/Gems/1.8/gems/mysql2-0.2.6/lib/mysql2/mysql2.bundle

This is as far as I can get. What should I do? And why should this be so hard…

Answer 1

Snow Leopard supplies Ruby 1.8.7. Ruby 1.8.7 doesn’t automatically add the require 'rubygems' command to a Ruby script, like 1.9.2 will, so in general you need to add that to your script. That fixes the problems with Ruby not finding the gems called by your code in a lot of cases. Rails is a different animal, but the version with 1.8.7 is well documented so you should have found a fix pretty quickly.

The Ruby supplied by Snow Leopard is really for its own use. Users can piggyback on that, but it’s installed by Apple because they have applications that use it. Use locate podcast | grep rb$ to see. Similarly, Perl and Python in Snow Leopard are used to support code Apple has installed so messing with them is not a good idea. Changing the built-in Ruby, Perl or Python usually won’t cause the system to explode in flames, but it can cause irritating and unexplained problems farther down the road when system maintenance routines stop working.

By using sudo to remove gems installed by Apple and add new ones, you’ve left your system Ruby in an unexpected state as far as Apple’s apps are concerned. Rather than mess with Apple’s Ruby, you should install a separate Ruby for your own use using Fink or MacPorts, or from source code, or by using RVM.

Personally, I use RVM because it creates a ~/.rvm sandbox in your home directory, and makes it easy to manage multiple versions of Ruby and gems. RVM requires you to install the XCode development library, which you can download from http://developer.apple.com/technologies/ after a free registration. XCode is also on your system DVD, but that version is reported to be buggy, so use the downloaded version.