Rig to demonstrate my problem using rbenv exec.

.rbenv-version

system

.rbenv-version

1.9.2-p290

README.md

This is a quick rig to demonstrate my problem using rbenv exec.

Run:

cd parent
ruby test.rb

• The parent should run on Ruby 1.9.2-p290
• It should then fork a child that runs on system ruby
• It then tries again setting RBENV_VERSION=system too.

Expected: Parent and child should run on different versions of Ruby.

Actual: The version of Ruby never changes.

I think the .rbenv-version files are set up correctly because:

$ cd parent
$ rbenv local
1.9.2-p290
$ cd ../child
$ rbenv local
system
$ rbenv shell
rbenv: no shell-specific version configured

Output

Output on my system

$ cd parent
$ ruby test.rb

in parent, .rbenv-version file specifies 1.9.2-p290
    version=1.9.2: /home/bronson/.rbenv/versions/1.9.2-p290/bin/ruby
    executing child...

in child, .rbenv-version file specifies system
    version=1.9.2: /home/bronson/.rbenv/versions/1.9.2-p290/bin/ruby
    cwd is /tmp/1275927/child

back in parent, .rbenv-version file specifies 1.9.2-p290
    version=1.9.2: /home/bronson/.rbenv/versions/1.9.2-p290/bin/ruby
    executing child using RBENV_VERSION=system too...

in child, .rbenv-version file specifies system
    version=1.9.2: /home/bronson/.rbenv/versions/1.9.2-p290/bin/ruby
    cwd is /tmp/1275927/child

test.rb

#!/usr/bin/env ruby

puts "in child, .rbenv-version file specifies system"
puts "    version=#{RUBY_VERSION}: " + `which ruby`
puts "    cwd is " + Dir.pwd

test.rb

#!/usr/bin/env ruby

puts "in parent, .rbenv-version file specifies 1.9.2-p290"
puts "    version=#{RUBY_VERSION}: " + `which ruby`
puts "    executing child..."
puts

Dir.chdir "../child" do
  system "ruby test.rb"
end

puts
puts "back in parent, .rbenv-version file specifies 1.9.2-p290"
puts "    version=#{RUBY_VERSION}: " + `which ruby`
puts "    executing child using RBENV_VERSION=system too..."
puts

Dir.chdir "../child" do
  ENV['RBENV_VERSION'] = 'system';
  system "ruby test.rb"
end