how can i generate a diagram from a rails project?

i am trying to generate a rails diagram from a project with railroad. but i am getting a railroad: command not found even after installing the plugin : sudo gem install roadrail what is the problem? is there an alternative to that plugin? thank you for you h开发者_如何学JAVAelp

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To install, the command is:

sudo gem install railroad

not roadrail. Verify that the gem is installed by

sudo gem list railroad