Cannot run Jekyll on Ubuntu 12.04 - ruby

Question

I encountered this issue:
gabriele # osiris { ~ } [ ven nov 15 ] [ 12:57 ]
> jekyll
/var/lib/gems/1.8/gems/highline-1.6.19/lib/highline/system_extensions.rb:210: warning: Insecure world writable dir /home/gabriele in PATH, mode 040777
/var/lib/gems/1.8/gems/commander-4.1.3/lib/commander/runner.rb:365:in `require_program': program version required (Commander::Runner::CommandError)
from /var/lib/gems/1.8/gems/commander-4.1.3/lib/commander/runner.rb:364:in `each'
from /var/lib/gems/1.8/gems/commander-4.1.3/lib/commander/runner.rb:364:in `require_program'
from /var/lib/gems/1.8/gems/commander-4.1.3/lib/commander/runner.rb:52:in `run!'
from /var/lib/gems/1.8/gems/commander-4.1.3/lib/commander/delegates.rb:7:in `run!'
from /var/lib/gems/1.8/gems/commander-4.1.3/lib/commander/import.rb:10
from /usr/local/bin/jekyll:19
/usr/lib/ruby/vendor_ruby/1.8/rubygems/custom_require.rb:36:in `gem_original_require': no such file to load -- json (LoadError)
from /usr/lib/ruby/vendor_ruby/1.8/rubygems/custom_require.rb:36:in `require'
from /var/lib/gems/1.8/gems/jekyll-1.3.0/bin/../lib/jekyll/filters.rb:2
from /usr/lib/ruby/vendor_ruby/1.8/rubygems/custom_require.rb:36:in `gem_original_require'
from /usr/lib/ruby/vendor_ruby/1.8/rubygems/custom_require.rb:36:in `require'
from /var/lib/gems/1.8/gems/jekyll-1.3.0/bin/../lib/jekyll.rb:43
from /usr/lib/ruby/vendor_ruby/1.8/rubygems/custom_require.rb:36:in `gem_original_require'
from /usr/lib/ruby/vendor_ruby/1.8/rubygems/custom_require.rb:36:in `require'
from /var/lib/gems/1.8/gems/jekyll-1.3.0/bin/jekyll:7
from /usr/local/bin/jekyll:19:in `load'
from /usr/local/bin/jekyll:19
after I've installed jekyll on Ubuntu 12.04 with
sudo apt-get install ruby1.9.1-dev && sudo gem install jekyll
This is my gem env:
RubyGems Environment:
- RUBYGEMS VERSION: 1.8.15
- RUBY VERSION: 1.8.7 (2011-06-30 patchlevel 352) [x86_64-linux]
- INSTALLATION DIRECTORY: /var/lib/gems/1.8
- RUBY EXECUTABLE: /usr/bin/ruby1.8
- EXECUTABLE DIRECTORY: /usr/local/bin
- RUBYGEMS PLATFORMS:
- ruby
- x86_64-linux
- GEM PATHS:
- /var/lib/gems/1.8
- /home/gabriele/.gem/ruby/1.8
- GEM CONFIGURATION:
- :update_sources => true
- :verbose => true
- :benchmark => false
- :backtrace => false
- :bulk_threshold => 1000
- REMOTE SOURCES:
- http://rubygems.org/
How can i solve it?

Answer 1

Running gem install json should fix the LoadError.
Commander throws that program version required error whenever there is a problem loading in the executable (in this case, bin/jekyll). As 1.8.7 can't load an internal json library (introduced in 1.9), you'll need to install the gem.