Q:

installing ruby on rails on passenger dosn't work

is there a good and simple installation guide how to install phusion passenger on my apache2 and then install ruby on rails?
I'm using debian 7
i've done point 2.31 and 2.3.2
https://www.phusionpassenger.com/documentation/Users%20guide%20Apache.html#rubygems_generic_install
then I tried this: $ gem install rails
and got this error

A:

You don't have the -dev package installed, so it can't find mkmf.
Run sudo apt-get install ruby1.9.1-dev to install the dev package for 1.9.1

