Why is Rubygems not able to install Rails?

Question

I am trying to install rails using the command

gem install rails

on my ubuntu 12.04 . Also I have configured my apt.conf file with the username , password and proxy details . Then too the execution of this command gives an error as :

ERROR: While executing gem ... (Net::HTTPServerException)
407 "Proxy Authentication Required"

If I run

sudo gem install rails

the errors are :

ERROR: While executing gem ... (Gem::DependencyError)
Unable to resolve dependencies: treetop requires polyglot (>= 0), polyglot (>= 0.3.1); sprockets requires tilt (!= 1.3.0, ~> 1.1)

My local gem list is as follows :

* LOCAL GEMS *
actionmailer (4.0.1)
actionpack (4.0.1)
activemodel (4.0.1)
activerecord (4.0.1)
activerecord-deprecated_finders (1.0.3)
activesupport (4.0.1)
arel (4.0.1)
atomic (1.1.14)
bigdecimal (1.2.0)
builder (3.1.4)
bundler (1.3.5)
bundler-unload (1.0.2)
coffee-rails (4.0.1)
coffee-script (2.2.0)
coffee-script-source (1.6.3)
erubis (2.7.0)
execjs (2.0.2)
executable-hooks (1.2.6)
hike (1.2.3)
i18n (0.6.5)
io-console (0.4.2)
jbuilder (1.5.2)
jquery-rails (3.0.4)
json (1.8.1, 1.7.7)
mail (2.5.4)
mime-types (1.25)
minitest (4.7.5, 4.3.2)
multi_json (1.8.2)
polyglot (0.3.3)
psych (2.0.0)
rack (1.5.2)
rack-test (0.6.2)
rails (4.0.1)
railties (4.0.1)
rake (10.1.0, 0.9.6)
rdoc (4.0.1, 4.0.0, 3.12.2)
rubygems-bundler (1.4.2)
rvm (1.11.3.8)
sass (3.2.12)
sass-rails (4.0.1)
sdoc (0.3.20)
sprockets (2.10.0)
sprockets-rails (2.0.1)
sqlite3 (1.3.8)
test-unit (2.0.0.0)
thor (0.18.1)
thread_safe (0.1.3)
tilt (1.4.1)
treetop (1.4.15)
turbolinks (1.3.0)
tzinfo (0.3.38)
uglifier (2.3.0)

I have already run "rvm requirements" and I have tried using SET HTTP_PROXY but it also doesn't have any affect . What should I do ?

EDIT:

I tried using

export http_proxy=http://${username}:${password}@${proxy}:${port}

and then ran gem install rails and it worked ...

Answer 1

super user and normal user has different gem list. I think super user does not have polyglot and tilt.

Try:

sudo gem install polyglot
sudo gem install tilt

Please check gem list of super user.

sudo gem list