Package: ruby

"ruby" package binaries on CentOS:

/usr/bin/erb /usr/bin/ruby /usr/bin/testrb

You may install this package on CentOS with yum install ruby

"ruby" package binaries on Debian:

/usr/bin/erb /usr/bin/gem /usr/bin/irb /usr/bin/rdoc /usr/bin/ri /usr/bin/ruby /usr/bin/testrb

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