A tiny program to mangle the authentication URL produced by
http://liboauth.sourceforge.net/
(apt-get liboauth-dev or brew install liboauth)
into the Authorization header that Twitter wants.
If you have set up an account at https://dev.twitter.com/apps that has
Consumer key A
Consumer secret B
Access token C
Access token secret D
and you want to access, say, https://stream.twitter.com/1.1/statuses/filter.json?locations=-180,-90,180,90 you can do
$ url='https://stream.twitter.com/1.1/statuses/filter.json?locations=-180,-90,180,90'
$ curl --compress -s --header "$(./auth "$url" A B C D)" "$url"
to authenticate it and watch the stream.