Package: ruby-standalone

"ruby-standalone" package binaries on Debian:

/usr/bin/ruby-standalone /usr/lib/ruby-standalone/bin/erb /usr/lib/ruby-standalone/bin/gem /usr/lib/ruby-standalone/bin/irb /usr/lib/ruby-standalone/bin/rake /usr/lib/ruby-standalone/bin/rdoc /usr/lib/ruby-standalone/bin/ri /usr/lib/ruby-standalone/bin/ruby2.1 /usr/lib/ruby-standalone/bin/ruby /usr/lib/ruby-standalone/bin/testrb

You may install this package on Debian with apt-get install ruby-standalone