Failed to build gem native extension — Rails install

Question

I have been installing Ruby on Rails based on the instruction from edX online class.

Here is a list of terminal commands, and, where relevant, corresponding output

Answer 1

mkmf is part of the ruby1.9.1-dev package. This package contains the header files needed for extension libraries for Ruby 1.9.1. You need to install the ruby1.9.1-dev package by doing:

sudo apt-get install ruby1.9.1-dev

Then you can install Rails as per normal.

Generally it's easier to just do:

sudo apt-get install ruby-dev

Answer 2

The suggested answer only works for certain versions of ruby. Some commenters suggest using ruby-dev; that didn't work for me either.

sudo apt-get install ruby-all-dev

worked for me.

Answer 3

sudo apt-get install ruby-dev

worked for me