Trying Ruby: why can't I install nanoc?

I try to install nanoc http://nanoc.stoneship.org/docs/2-installation/

by typing in irb

gem install nano

it says undef开发者_如何学Pythonined variable or method 'nanoc' ?

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You need to install it from the shell, not IRB. Gem is a command, i.e.

% which gem

/usr/bin/gem

% gem install nanoc

ian.

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That gem install command is meant to be run in your normal system shell (something like Bash, for example).

irb is a Ruby shell, it interactively executes Ruby code. You'll notice that the instructions you link to immediately tell you to quit irb after starting it (they only told you to run it to make sure Ruby was installed).