Install PostgreSQL on Ubuntu for Rails developers
Aug 29, 14 by Juan Lebrijo about postgresql, ruby on rails, blog
These instructions worked for Ubuntu 12-14. Check the language in the system:
env | grep LC_
It should be "en_US.UTF-8", if not you can configure in "System Setting > Language Support". Installing DDBB and libpq-dev to compile rails gem when bundling, with following command:
sudo apt-get install postgresql libpq-dev
To gain access from the server it-self, In /etc/postgresql/9.3/main/postgresql.conf, uncomment the following line:
listen_addresses = 'localhost'
To have access from rails app, modify the following line in /etc/postgresql/9.1/main/pg_hba.conf:
# "local" is for Unix domain socket connections only
local   all             all                                     md5
Restart the service:
sudo service postgresql restart
You will need to add a role:
sudo -u postgres psql
create role pg_user with createdb login password 'pg_user';
Be sure that your Gemfile includes: gem 'pg' Create your database.yml for dev and test:
common: &common
  adapter: postgresql
  username: pg_user
  password: pg_user

development:
  <
Create and fill the database:
rake db:create
rake db:migrate
rake db:seed
Some Postgre useful commands are:
  • List of databases: sudo -u postgres psql -l
  • Check server encoding: sudo -u postgres psql -c "SHOW SERVER_ENCODING"
PostgreSQL Backup/Restore
Aug 28, 14 by Juan Lebrijo about Database, postgresql, blog
Continuing my notes publishing ... How to backup/restore your PostgreSQL databases? when you recently get the responsibility of a web app? or you will renew your development environment? or you want to reproduce a production error in your machine? or you want to sleep better at night ;-) ? or ....? whatever. Before to do anything always we should log as postgres user:
sudo su - postgres
Then backup one database:
pg_dump database_name > /tmp/database_name.bak
Or backup them all:
pg_dumpall > /tmp/backup_all.bak
After that you probably want to download them from server to your machine:
scp your.server.com:/tmp/backup_all.bak .
And finally you want to restore one database, but you will need to create the database previously:
createdb -T template0 database_name
psql database_name < database_name.bak
Maybe you also need to create a user and give it proper permissions:
psql
create role user_name with createdb login password 'user_password';
Or restore them all:
psql -f backup_all.bak postgres
This will create all databases and users for you.
Converting RGB colors to Hexadecimal with ruby
Aug 27, 14 by Juan Lebrijo about ruby, blog
Just a tip to convert RGB colors to Hexadecimal:
  def rgb(r, g, b)
    "##{to_hex r}#{to_hex g}#{to_hex b}"
  end
  def to_hex(n)
    n.to_s(16).rjust(2, '0').upcase
  end
In console:
rgb(50, 205, 50)
=> "#32CD32"