Intalling the PostgreSQL gem pq for Heroku - ruby-on-rails

Question

First question here, but I want to thank you very much now, because stackoverflow helped me almost 15 times just in the first chapter of michael hartl tut.
Now I'm trying to install PostgreSQL (pg gem) with this command:
`
group :production do
gem 'pg', '0.15.1'
gem 'rails_12factor', '0.0.2'
end`
but it shows an ERROR
-bash: group: command not found
Then I tried to install directly (?) the gem with
gem install pg
But it shows another ERROR
`Fetching: pg-0.17.1.gem (100%)
Building native extensions. This could take a while...
ERROR: Error installing pg:
ERROR: Failed to build gem native extension.
rvm/rubies/ruby-2.0.0-p353/bin/ruby extconf.rb
checking for pg_config... no
No pg_config... trying anyway. If building fails, please try again with
--with-pg-config=/path/to/pg_config
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers. Check the mkmf.log file for more details. You may
need configuration options.
Provided configuration options:
--with-opt-dir
--without-opt-dir
--with-opt-include
--without-opt-include=${opt-dir}/include
--with-opt-lib
--without-opt-lib=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/Users/trabalho/.rvm/rubies/ruby-2.0.0-p353/bin/ruby
--with-pg
--without-pg
--with-pg-config
--without-pg-config
--with-pg_config
--without-pg_config
--with-pg-dir
--without-pg-dir
--with-pg-include
--without-pg-include=${pg-dir}/include
--with-pg-lib
--without-pg-lib=${pg-dir}/
extconf failed, exit code 1
Gem files will remain installed in .rvm/gems/ruby-2.0.0-p353#railstutorial_rails_4_0/gems/pg-0.17.1 for inspection.
Results logged to .rvm/gems/ruby-2.0.0-p353#railstutorial_rails_4_0/extensions/x86_64-darwin-10/2.0.0/pg-0.17.1/gem_make.out`
I can't understand if it was installed or not, neither how can I confirm. How do I put the group command working? Or how can I install the gem pg and rails_12factor?
Any help?

Answer 1

Are you running ubuntu? Looks like you need this library:
sudo apt-get install libpq-dev
Source

Answer 2

You don't want to run group ... as a command from your terminal but rather put that code block inside of the Gemfile of your rails application.
Gemfile
group :production do
gem 'pg', '0.15.1'
gem 'rails_12factor', '0.0.2'
end
Then run the bundle command.
If you are still unable to compile the pg gem this way then you'll need to make sure that you have the xcode command line tools installed (assuming you're using OSX). To install these just run xcode-select --install from your terminal and follow the prompts.

Answer 3

sudo apt-get install libpq-dev
it's helped me on Ubuntu