Recently I have updated ruby from 19 to 20, and rake also updated.

When I use rake generate in octopress, it throws an error:

tankywoo::octopress/ (source*) » rake generate
rake aborted!
You have already activated rake 0.9.6, but your Gemfile requires rake Using bundle exec may solve this.
/home/tankywoo/.gem/ruby/1.9.1/gems/bundler-1.3.5/lib/bundler/runtime.rb:33:in `block in setup'
/home/tankywoo/.gem/ruby/1.9.1/gems/bundler-1.3.5/lib/bundler/runtime.rb:19:in `setup'
/home/tankywoo/.gem/ruby/1.9.1/gems/bundler-1.3.5/lib/bundler.rb:120:in `setup'
/home/tankywoo/.gem/ruby/1.9.1/gems/bundler-1.3.5/lib/bundler/setup.rb:7:in `<top (required)>'
/home/tankywoo/octopress/Rakefile:2:in `<top (required)>'
(See full trace by running task with --trace)

One way is to use bundle exec rake xxx instead of rake xxx.

The better way is:

Modify the require rake version in Gemfile.

gem 'rake', '~> 0.9'  ---> gem 'rake', '~> 0.9.6'


bundle update rake