Problem Installing Rails 3

I'm trying to install Rails 3 on a brand new MacBook Pro running OS X
10.6.3, Ruby 1.8.7, and Rails 2.3.5 and I'm wondering if I've hosed
myself. So far, I've run these commands:

$ gem update --system
$ gem install arel tzinfo builder memcache-client rack rack-test rack-
mount erubis mail text-format thor bundler i18n
$ gem install rails --pre

However, when I run the last command, I get this error:

ERROR: While executing gem ... (Gem::FilePermissionError)
    You don't have write permissions into the /usr/bin directory.

I think it wants me to run the command with sudo so that it can write
over /usr/bin/rails. But if I do that, won't I be overwriting my
Rails 2.3.5 executable? I don't want to do that. Instead, I'd like
to keep both versions of Rails. Can anyone help?


You need to get into the system.

Try typing sudo (aka super user/super admin)

$ sudo

it'll prompt you to put in your password if you are the admin of your

Once you're in and have the permisison, you can install rails. (sudo
will stay in your command prompt until you exit from it)

$ sudo gem install rails

sorry didn't read your question completely

You can choose your version using this command:

rails _2.3.5_ --version

You can change between versions if you do this and shouldn't harm
whatever project you have under an old rails verion

Thanks. I do understand that. However, my question is that if I
execute the command "sudo gem install rails --pre", won't I be
overwriting my existing Rails 2.3.5 executable which resides in /usr/
bin? That's what I'm really worried about. I'd like to be able to
have both Rails 2.3.5 and the Rails 3 beta existing on my machine at
the same time. Would running the gem install command alter my /usr/
bin/rails executable such that it would contain both versions or
should it create a separate and distinct Rails 3 beta executable?

Thanks again. I really do appreciate your help.

I'm sorry. I wouldn't be able to know as I've never installed Rails 3
Hopefully someone here has and will be able to help you.

Have you *looked* at that "executable"? :slight_smile:

It might go a long way towards alleviating your concern.

I think this article by Brian Cardarella may answer my question. I'll
figure this out and document what I had to do for all the other
"noobs" out there.