# Force gem to use a given version of library

**URL:** <https://www.ruby-forum.com/t/force-gem-to-use-a-given-version-of-library/163323>\
**Category:** Ruby\
**Created:** [March 19, 2009, 9:32am UTC](https://www.ruby-forum.com/t/force-gem-to-use-a-given-version-of-library/163323 "2009-03-19T09:32:59Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![edouard](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/c57346/32.png) [@edouard](https://www.ruby-forum.com/u/edouard)\
**Post date:** [March 19, 2009, 9:32am UTC](https://www.ruby-forum.com/t/force-gem-to-use-a-given-version-of-library/163323/1 "2009-03-19T09:32:59Z")

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hi,

i have to install a gem and force it to use a given version of two  
installed library, (removing the older will trash my system)

how can i tell gem to use the version i want?

thanks

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**Author:** ![edouard](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/c57346/32.png) [@edouard](https://www.ruby-forum.com/u/edouard)\
**Post date:** [March 19, 2009, 1:58pm UTC](https://www.ruby-forum.com/t/force-gem-to-use-a-given-version-of-library/163323/2 "2009-03-19T13:58:57Z")

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On Mar 19, 2009, at 4:30 AM, Edouard D. wrote:

> hi,
> 
> i have to install a gem and force it to use a given version of two  
> installed library, (removing the older will trash my system)
> 
> how can i tell gem to use the version i want?
> 
> ## thanks
> 
> Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/).

require ‘rubygems’  
gem ‘htmlentities’, ‘=4.0.0’  
gem ‘builder’, ‘~\> 2.0’

See [http://rubygems.org/read/chapter/4](http://rubygems.org/read/chapter/4)  
and [http://rubygems.org/read/chapter/16](http://rubygems.org/read/chapter/16)

Except any time you read “require\_gem” just mentally change that to  
“gem”

-Rob

Rob B. [http://agileconsultingllc.com](http://agileconsultingllc.com)  
removed\_email\_address@domain.invalid

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<div class="post-metadata">

**Author:** ![edouard](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/c57346/32.png) [@edouard](https://www.ruby-forum.com/u/edouard)\
**Post date:** [March 20, 2009, 12:01am UTC](https://www.ruby-forum.com/t/force-gem-to-use-a-given-version-of-library/163323/3 "2009-03-20T00:01:24Z")

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On Mar 19, 2009, at 05:55, Rob B. wrote:

> See [http://rubygems.org/read/chapter/4](http://rubygems.org/read/chapter/4)  
> and [http://rubygems.org/read/chapter/16](http://rubygems.org/read/chapter/16)
> 
> Except any time you read “require\_gem” just mentally change that to  
> “gem”

I just updated those chapters to remove require\_gem. Let me know if  
you find others.