I've been having a lot of trouble with my Ruby 1.9.1 install on Mac OS X. Mostly it works fine, but I struggle when installing gems that require native extensions. I think this is because the way my install was built causes linkage problems, perhaps due to 32 vs 64 bit issues, or due to linkage with other libraries. I'm not entirely sure what's causing the problems, but recently I decided enough was enough and tried out rvm since I've heard a lot of good things about it. I got the impression that by compiling from my own source I was stubbornly making a lot of my own trouble.

Rvm is trivial to install: it's a gem that installs some of its own executables. I did hack my PATH first, to remove /usr/local/bin (where my custom Ruby lived) so that I'd be using the stock Mac OS X Ruby for the rvm install.

> sudo gem install rvm
> rvm-install

Note that rvm-install added the following to the end of ~/.bash_profile automatically, so I could ignore the instruction it gave me about adding it myself:

if [ -s ~/.rvm/scripts/rvm ] ; then source ~/.rvm/scripts/rvm ; fi

I then used rvm to install a fresh version of Ruby 1.9.1:
>> rvm install 1.9.1

Actually that failed with an error about libsqlite3.dylib being the wrong architecture – perhaps another hangover from my old manual installs, or a problem I'm going to have to solve sometime in the future! For now I moved the old version of that file and tried again:

> sudo mv /usr/local/lib/libsqlite3.dylib /usr/local/lib/libsqlite3.dylibOLD
> rvm install 1.9.1

And that left me with a decent ruby 1.9.1 install. Which brought me back to one of the things that I was originally frustrated by: getting NetBeans Ruby debugging working with the fast debugger. With my old install the ruby-debug-ide gem would not install, but I'm pleased to report that it does with this new setup.

However getting NetBeans to actually use my new rvm ruby required a bit of a trick. The Ruby Platform management GUI in NetBeans doesn't show you hidden folders in its file picker, so you can't navigate to the ~/.rvm/ruby-1.9.1-p243/bin/ruby file that it wants. The trick is to create a non-hidden symlink, so you can then find it from NetBeans (and it's also handy to get at your rvm files from Finder):

> ln -s ~/.rvm ~/rvm

One word of warning: once you're using an RVM Ruby install, do not use sudo for gem installs, as the gems (and every part of rvm) live in ~/.rvm so sudo is not required. In fact using sudo will knacker your gems quite badly as it gets its PATH wrong and its permissions and you end up deleting a bunch of stuff to get back to a known good state. I learnt this the hard way!