Error on gem version when installing

Question

I am trying to install the github-pages gem on Ubuntu 14.04.

I get this error about the version of a dependency (with or without sudo doesn't change the outcome):

$ sudo gem2.0 install github-pages

ERROR:  While executing gem ... (Gem::DependencyError)
Unable to resolve dependencies: github-pages-health-check requires public_suffix (~> 1.4)

However, doing gem2.0 list --local shows me:

public_suffix (2.0.4)

What's the problem here? I have 2 coexisting versions of ruby (ruby1.9.3 and ruby2.0), but I have made /usr/bin/ruby link to ruby2.0.

Answer 1

~> is a pessimistic version constraint. ~> 1.4 means >= 1.4 and < 2.0 , and your version of public_suffix is not in that range. Try

gem install public_suffix -v 1.5.3

which is the newest version that actually satisfies the constraint.