Just in case you are having trouble with your Windows path variable, 
here's how to add a folder to it:

*Go to your desktop and right click "My Computer".

*Select "properties" from the menu.

*Click the "Advanced" tab.

*At the bottom of the window, there's a button labeled "Environment 
Variables". Click it.

*There are two listboxes on the window, the bottom one is called "System 
variables". Scroll through that box until you come across "Path". Select 
"Path" and click the "Edit" button.

*Click the "Variable value" textbox and hit the "End" key on your 
keyboard. Type a semi-colon followed by the absolute path to your ruby 
bin folder.

Also, you can always check what folder IRB is running in by typing 
"Dir.pwd". You can get a list of all the .rb file in the folder IRB is 
currently operating in with "Dir.glob('*.rb')". Also, you can change the 
path that IRB is operating in with "Dir.chdir('c:\my_ruby_files\')".
-- 
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