Ruby - Remove all other characters from a String

I have a string h2#test- ruby is so awesome, blah, blah, blah. I want to have #test to be the only characters left. is th开发者_JAVA技巧ere a way in ruby to run a Regular Expression that removes all other characters?

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str.match(/(\#\w+)/)[1]

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Don't think of it as removing all other characters...think of it as capturing what you want.

'h2#test- ruby is so awesome, blah, blah, blah' =~ /(#test)/
your_captured_text = $1

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str[/#[a-z]+/i]