ruby LoadError: cannot load such file

Question

When I require a file, for example (called st.rb):

require 'rubygems' require 'mongrel'  class TestHandler < Mongrel::HttpHandler    def process(request, response)     response.start(200) do |head, out|       head["Content-Type"] = "text/html"       out.write "Hello, World!\n"     end   end  end 

in irb I get:

>> require 'st.rb' LoadError: cannot load such file -- st.rb     from /usr/local/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require'     from /usr/local/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require'     from (irb):3     from /usr/local/bin/irb:12:in `<main>' 

I might have a clue, but it's just a guess. My ruby version/install location is:

/usr/local/bin/ruby and ruby 1.9.3p0

yet, ruby gems is in /usr/local/lib/ruby/1.9.1 and it's talking about version 1.9.1. Could this possibly be the reason?

Thanks!

UPDATE Weird, when I type 'puts RUBY_VERSION' in IRB, I get this:

puts RUBY_VERSION 1.9.3 NoMethodError: undefined method `write' for nil:NilClass     from /usr/local/lib/ruby/1.9.1/irb.rb:311:in `printf'     from /usr/local/lib/ruby/1.9.1/irb.rb:311:in `output_value'     from /usr/local/lib/ruby/1.9.1/irb.rb:160:in `block (2 levels) in eval_input'     from /usr/local/lib/ruby/1.9.1/irb.rb:273:in `signal_status'     from /usr/local/lib/ruby/1.9.1/irb.rb:156:in `block in eval_input'     from /usr/local/lib/ruby/1.9.1/irb/ruby-lex.rb:243:in `block (2 levels) in each_top_level_statement'     from /usr/local/lib/ruby/1.9.1/irb/ruby-lex.rb:229:in `loop'     from /usr/local/lib/ruby/1.9.1/irb/ruby-lex.rb:229:in `block in each_top_level_statement'     from /usr/local/lib/ruby/1.9.1/irb/ruby-lex.rb:228:in `catch'     from /usr/local/lib/ruby/1.9.1/irb/ruby-lex.rb:228:in `each_top_level_statement'     from /usr/local/lib/ruby/1.9.1/irb.rb:155:in `eval_input'     from /usr/local/lib/ruby/1.9.1/irb.rb:70:in `block in start'     from /usr/local/lib/ruby/1.9.1/irb.rb:69:in `catch'     from /usr/local/lib/ruby/1.9.1/irb.rb:69:in `start'     from /usr/local/bin/irb:12:in `<main>' Maybe IRB bug! >>  

Answer 1

The directory where st.rb lives is most likely not on your load path.

Assuming that st.rb is located in a directory called lib relative to where you invoke irb, you can add that lib directory to the list of directories that ruby uses to load classes or modules with this:

$: << 'lib' 

For example, in order to call the module called 'foobar' (foobar.rb) that lives in the lib directory, I would need to first add the lib directory to the list of load path. Here, I am just appending the lib directory to my load path:

irb(main):001:0> require 'foobar' LoadError: no such file to load -- foobar         from /usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:36:in `gem_original_require'         from /usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:36:in `require'         from (irb):1 irb(main):002:0> $: => ["/usr/lib/ruby/gems/1.8/gems/spoon-0.0.1/lib", "/usr/lib/ruby/gems/1.8/gems/interactive_editor-0.0.10/lib", "/usr/lib/ruby/site_ruby/1.8", "/usr/lib/ruby/site_ruby/1.8/i386-cygwin", "/usr/lib/ruby/site_ruby", "/usr/lib/ruby/vendor_ruby/1.8", "/usr/lib/ruby/vendor_ruby/1.8/i386-cygwin", "/usr/lib/ruby/vendor_ruby", "/usr/lib/ruby/1.8", "/usr/lib/ruby/1.8/i386-cygwin", "."] irb(main):004:0> $: << 'lib' => ["/usr/lib/ruby/gems/1.8/gems/spoon-0.0.1/lib", "/usr/lib/ruby/gems/1.8/gems/interactive_editor-0.0.10/lib", "/usr/lib/ruby/site_ruby/1.8", "/usr/lib/ruby/site_ruby/1.8/i386-cygwin", "/usr/lib/ruby/site_ruby", "/usr/lib/ruby/vendor_ruby/1.8", "/usr/lib/ruby/vendor_ruby/1.8/i386-cygwin", "/usr/lib/ruby/vendor_ruby", "/usr/lib/ruby/1.8", "/usr/lib/ruby/1.8/i386-cygwin", ".", "lib"] irb(main):005:0> require 'foobar' => true 

EDIT Sorry, I completely missed the fact that you are using ruby 1.9.x. All accounts report that your current working directory has been removed from LOAD_PATH for security reasons, so you will have to do something like in irb:

$: << "."