More rbenv notes

My last post on rbenv mentioned some things you need to do to get ruby to build on Mountain Lion. Here are a few more things.

This guy Jacob Swanner didn’t want to use either Xcode or gcc. He just used the Xcode command-line tools, with a CC environment variable, thus:

$ CC=/usr/bin/clang rbenv install 1.9.3-p194
$ rbenv global 1.9.3-p194

That won’t work with older versions of Ruby, however, as I mentioned before.

I noted he is also a Homebrew user. I’m not yet ready to go there, although macports gets more and more frustrating with each OS release. (I’m not alone.) (But that’s a subject for some other time.)

And, for convenience, here’s another Homebrewer’s notes on how to get ruby building again with Mountain Lion

rbenv notes

I used to use rvm to manage my ruby environment, but the latest hotness seems to be rbenv. Here are some tips about using it. They’re aimed at me, because by the next time I need to use it, I’ll have forgotten. But you can read them too:

One of the things you want is rbenv-build:

Installing ruby-build as an rbenv plugin will give you access to the rbenv install command.

$ mkdir -p ~/.rbenv/plugins
$ cd ~/.rbenv/plugins
$ git clone git://

(Note the assumption you’re using git. I don’t know what people who prefer mercurial are supposed to do.)

This will install the latest development version of ruby-build into the ~/.rbenv/plugins/ruby-build directory. From that directory, you can check out a specific release tag. To update ruby-build, run git pull to download the latest changes.

But that won’t work with Mountain Lion. So you’ll need a version of ruby that can be built with clang.

$ rbenv install 1.9.3-p125

Ruby and Mac OS X Lion

When Apple switched from GCC to LLVM in Xcode 4.2, they made it significantly more difficult for me to run ruby 1.9.2. (What are the odds this will get easier with Mountain Lion?)

I was using rbenv and its rbenv-build plugin to install ruby 1.9.2 and it told me this:

$ rbenv install 1.9.2-p320

ERROR: This package must be compiled with GCC, but ruby-build couldn't
find a suitable `gcc` executable on your system. Please install GCC
and try again.

DETAILS: Apple no longer includes the official GCC compiler with Xcode
as of version 4.2. Instead, the `gcc` executable is a symlink to
`llvm-gcc`, a modified version of GCC which outputs LLVM bytecode.

For most programs the `llvm-gcc` compiler works fine. However,
versions of Ruby older than 1.9.3-p125 are incompatible with
`llvm-gcc`. To build older versions of Ruby you must have the official
GCC compiler installed on your system.

TO FIX THE PROBLEM: Install the official GCC compiler using these

You will need to install the official GCC compiler to build older
versions of Ruby even if you have installed Apple's Command Line Tools
for Xcode package. The Command Line Tools for Xcode package only
includes `llvm-gcc`.

Note: when you install that, it doesn’t (appear to) provide an uninstaller. Instead it says this:

If something doesn’t work as expected, feel free to install Xcode over this installation.

Once installed, you can remove Xcode completely with the following:

sudo /Developer/Library/uninstall-devtools –mode=all

Bummer for me, huh? Mercifully, the GCC installation package doesn’t mess up the llvm-gcc link in /usr/bin/gcc. But that means when I do the ruby build, I need to add:

export CC=/usr/bin/gcc-4.2