# Specify older Rails when 2.x is installed...?

**URL:** <https://www.ruby-forum.com/t/specify-older-rails-when-2-x-is-installed/124559>\
**Category:** Rails\
**Created:** [December 30, 2007, 8:38am UTC](https://www.ruby-forum.com/t/specify-older-rails-when-2-x-is-installed/124559 "2007-12-30T08:38:48Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![davido](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/f475e1/32.png) [@davido](https://www.ruby-forum.com/u/davido)\
**Post date:** [December 30, 2007, 8:38am UTC](https://www.ruby-forum.com/t/specify-older-rails-when-2-x-is-installed/124559/1 "2007-12-30T08:38:48Z")

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I have multiple Rails gems installed on my system…

gem list | grep rails  
rails (2.0.2, 2.0.1, 1.2.6, 1.2.5)

Now, I want to make a new application based on Rails 1.2.6. I’m  
guessing that what I should have to do is something like this:

rails MyNewApp

And then in MyNewApp/config/environment.rb

Make sure the following is set for RAILS\_GEM\_VERSION:

RAILS\_GEM\_VERSION = ‘1.2.6’ unless defined? RAILS\_GEM\_VERSION

Before I do anything else… correct?

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<div class="post-metadata">

**Author:** ![davido](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/f475e1/32.png) [@davido](https://www.ruby-forum.com/u/davido)\
**Post date:** [December 30, 2007, 8:56am UTC](https://www.ruby-forum.com/t/specify-older-rails-when-2-x-is-installed/124559/2 "2007-12-30T08:56:20Z")

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On 30 Dec 2007, at 07:38, David Orriss Jr wrote:

> And then in MyNewApp/config/environment.rb
> 
> Make sure the following is set for RAILS\_GEM\_VERSION:
> 
> RAILS\_GEM\_VERSION = ‘1.2.6’ unless defined? RAILS\_GEM\_VERSION
> 
> Before I do anything else… correct?

Almost 🙂 That will do things like have a boot.rb from 2.0.2, the  
javascript files from 2.0.2 and some other things like that  
If you run  
rails _1.2.6_ myapp

Then it will run the rails from 1.2.6 and you shouldn’t have to mess  
around with anything.

Fred

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<div class="post-metadata">

**Author:** ![davido](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/f475e1/32.png) [@davido](https://www.ruby-forum.com/u/davido)\
**Post date:** [December 30, 2007, 9:11am UTC](https://www.ruby-forum.com/t/specify-older-rails-when-2-x-is-installed/124559/3 "2007-12-30T09:11:20Z")

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Frederick C. wrote:

> On 30 Dec 2007, at 07:38, David Orriss Jr wrote:
> 
> > And then in MyNewApp/config/environment.rb
> > 
> > Make sure the following is set for RAILS\_GEM\_VERSION:
> > 
> > RAILS\_GEM\_VERSION = ‘1.2.6’ unless defined? RAILS\_GEM\_VERSION
> > 
> > Before I do anything else… correct?
> 
> Almost 🙂 That will do things like have a boot.rb from 2.0.2, the  
> javascript files from 2.0.2 and some other things like that  
> If you run  
> rails _1.2.6_ myapp
> 
> Then it will run the rails from 1.2.6 and you shouldn’t have to mess  
> around with anything.
> 
> Fred

Thank you Fred. I’m most grateful for the assist and information! Have  
a Happy New Year.