rvmrc

You can have a .rvmrc file in three different places:

/etc/rvmrc sets options for the whole system;
~/.rvmrc sets options for the current user;
a .rvmrc file in a specific directory customizes things for that project.

The global and user .rvmrc files are mainly compile options for installing new Rubies. However, the project-specific .rvmrc files are the fun ones.

Here's how you do it:

when you start a new project, you'll what to create a .rvmrc file in that directory.
Let’s say you have a rails app that needs Ruby 1.8.6 to run; you have Ruby 1.9.2 as the default, and you don’t want to have to remember to switch Rubies when you’re working on that project.
So, type this command:
```
rvm --rvmrc --create 1.8.6-p334
```
This will create a heavily commented .rmvrc file that will change your Ruby environment when you switch into that directory.

It gets even better with gemsets.

I use Ruby 1.9.2 for all my projects, but I like to have a different gemset for each project. So, if I’ve got a project that’s called superproj, I can do this:
```
rvm --rvmrc --create 1.9.2@superproj
```
Just add an at-sign after the Ruby name and follow that with your gemset name.
This will load the right gems for that project. If this gemset hasn't been created yet, RVM will do that for you, too.

Sigue un ejemplo. Creo un .rvmrc en un directorio conteniendo el proyecto de un alumno:

[~/eleazar-src/prueba-activedirectory(testeo)]$ rvm --rvmrc --create 1.9.3-p392@eleazar-pfc

Veamos la cabecera del .rvmrc:

[~/eleazar-src/prueba-activedirectory(testeo)]$ head -3 .rvmrc 
#!/usr/bin/env bash

# This is an RVM Project .rvmrc file, used to automatically load the ruby

Ahora si entro en el directorio, la primera vez me lanza un warning:

[~/eleazar-src]$ rvm use 2.0.0-p0
Using /Users/casiano/.rvm/gems/ruby-2.0.0-p0
[~/eleazar-src]$ ruby -v
ruby 2.0.0p0 (2013-02-24 revision 39474) [x86_64-darwin11.4.2]
[~/eleazar-src]$ cd prueba-activedirectory/
You are using '.rvmrc', it requires trusting, it is slower and 
it is not compatible with other ruby managers,
you can switch to '.ruby-version' using 
            'rvm rvmrc to [.]ruby-version'
* Do you wish to trust '/Users/casiano/eleazar-src/prueba-activedirectory/.rvmrc'?  
y[es], n[o], v[iew], c[ancel]> y
-bash: /usr/bin/shasum: Permission denied
[~/eleazar-src/prueba-activedirectory(testeo)]$ ruby -v
ruby 1.9.3p392 (2013-02-22 revision 39386) [x86_64-darwin11.4.2]
[~/eleazar-src/prueba-activedirectory(testeo)]$

Para hacer que el mensaje de advertencia no aparezca:

$ rvm rvmrc warning ignore /Users/casiano/eleazar-src/prueba-activedirectory/.rvmrc
Using /Users/casiano/.rvm/gems/ruby-2.0.0-p0
$ cd prueba-activedirectory/
-bash: /usr/bin/shasum: Permission denied
$ ruby --version
ruby 1.9.3p392 (2013-02-22 revision 39386) [x86_64-darwin11.4.2]

Véanse:

Casiano Rodriguez León 2015-01-07