PostgreSQL gem pg was unable to install

try installing libpq package by doing:

sudo apt-get install libpq-dev

That package helps with pg gem and you should be fine after that :)

Here's my recipe for getting PostgreSQL, RVM, Ruby, Rails all up and running on CentOS

PostgreSQL

First, follow the instructions on http://wiki.postgresql.org/wiki/YUM_Installation to get PostgreSQL installed:

sudo vi /etc/yum.repos.d/CentOS-Base.repo

[base]
exclude=postgresql*

[updates]
exclude=postgresql*

Get the latest PGDG RPM file (for your platform/architecture), for example:

curl -O http://yum.postgresql.org/9.2/redhat/rhel-latest-x86_64/pgdg-redhat92-9.2-7.noarch.rpm

Then

sudo rpm -ivh pgdg-redhat92-9.2-7.noarch.rpm
sudo yum install -y postgresql92-server postgresql92-devel

Initialize the database:

sudo service postgresql-9.2 initdb

Configure /var/lib/pgsql/9.2/data/postgresql.conf and /var/lib/pgsql/9.2/data/pg_hba.conf as needed.

Start PostgreSQL server:

sudo service postgresql-9.2 start

RVM

sudo yum -y groupinstall "Development Tools"
sudo yum -y install zlib zlib-devel sqlite-devel httpd curl-devel httpd-devel apr-devel apr-util-devel mlocate man libxml2-devel libxslt-devel libffi-devel readline-devel

Note, NOT as root:

\curl -L get.rvm.io | sudo bash -s stable

Logout and back on. Afterwards, which rvm should reply with /usr/local/rvm/bin/rvm and type rvm|head -1 should say rvm is a function.

Ruby + Rails

rvm install 1.9.3 --with-openssl-dir=/usr
rvm use 1.9.3 --default
gem install rake
gem install rails

PostgreSQL gem

gem install pg -- --with-pg-config=/usr/pgsql-9.2/bin/pg_config

The --with-pg-config is somehow needed with my latest installation of CentOS, otherwise, gem install pg can't find pg_config. YMMV, but if you follow all the above to the letter (which I've done enough times in the past few months) just let me know if anything trips you up.

I got the same error on Centos. By googling I found two commands to use:

1. yum install postgresql-libs -- It gave me message saying, its already installed.
2. yum install postgresql-devel -- It solved my error related to pg_config for installing the 'pg' .gem.

Hope it helps :)

apos wrote: on Ubuntu 14.04 install:

1. apt-get install postgresql-server-dev-9.3 libpq-dev