Installing RMagick on Ubuntu 9.04 (Jaunty)


sudo apt-get install libmagickwand-dev imagemagick
sudo gem install rmagick


Ruby :: The bundled mysql.rb driver has been removed from Rails 2.2


sudo apt-get install libmysqlclient-dev
sudo gem install mysql


Easy Groups Authentication in Ruby on Rails using before_filter

first It's necessary to create two new tables: a table called groups with the fields (id, groupname, description) and other table called systables, with the fields (id, group_id, controller). Then create a file login_system.rb in the Lib folder under the main project. This file it's the library for send a filter to "before_filter" method in a rails controller. the modified code it's above:

require_dependency "user"
module LoginSystem
protected

def autorizado?(user, controller)
 @usuario= User.find(user)
 @grupo = @usuario.grupo.id.to_i
 @systable = Systable.find(:all, :conditions => ["grupo_id = ? and controller = ?", @grupo, controller])
 if @systable.empty?
  return false
 else
  return true
 end
end

#------ Group permissions ------------
def check_permissions
 if not protect?(action_name)
  return true
 end
 if @session['user'] and autorizado?(@session['user'], controller_name)
  return true
 end
 store_location
 access_denied
 return false
end

# overwrite if you want to have special behavior in case the user is not authorized
# to access the current operation. 
# the default action is to redirect to the login screen
# example use :
# a popup window might just close itself for instance

def access_denied
 redirect_to :controller=>"/account", :action =>"login"
end

# store current uri in the session.
# we can return to this location by calling return_location
def store_location
 @session['return-to'] = @request.request_uri
end

# move to the last store_location call or to the passed default one
def redirect_back_or_default(default)
 if @session['return-to'].nil?
 redirect_to default
else
 redirect_to_url @session['return-to']
 @session['return-to'] = nil
end
end

finally, in a controller write a line like this:

class CatalogosController < ApplicationController
    before_filter :check_permissions
end

Disable USB devices on GRUB in Ubuntu 9.10 Karmic Koala

For security it's important to disable all usb devices for not get out information, then I write a small bash script that do it. I hope that work succesfully.

#!/bin/bash
cp /etc/default/grub /tmp && cd /tmp
sed 's/splash/splash nousb/g' grub > grub.2 && sudo mv grub.2 /etc/default/grub
echo "Disable USB on GRUB..."

Generate new certificate for jabber server on OpenBSD

Modify the configuration file

sudo vi /etc/ejabberd/ejabberd.cfg

Modify the line for set certificate value before load the configuration file


[{5222, ejabberd_c2s, [{access, c2s},
{max_stanza_size, 65536},
starttls_required, {certfile, "/etc/ejabberd/server.pem"},
{shaper, c2s_shaper}]},


In the command line generate the key

openssl req -new -x509 -newkey rsa:1024 -days 3650 \
-keyout privkey.pem -out server.pem


openssl rsa -in privkey.pem -out privkey.pem

cat privkey.pem >> server.pem

rm privkey.pem


Finally restart the service


sudo ejabberctl restart


Active Record Without Rails and PostgreSQL

a script for connect a database and copy a single table in two tables, copy and save with the .rb extension for execute with Ruby, for example "inicio2tablas.rb" and run in a command line

 cmonterrosa@dibd02:~$ ./inicio2tablas.rb mydatabase myhost  

#!/usr/bin/ruby -w

require 'rubygems'
require 'active_record'

#--------- Carlos Augusto Monterrosa Lopez / cmonterrosa@gmail.com

def usage
STDERR.puts "Uso:
#{File.basename $0} dbname host"
exit 1
end

usage if ARGV.size != 2
dbname = ARGV[0]
host = ARGV[1]

ActiveRecord::Base.establish_connection(
:adapter => 'postgresql',
:database => dbname,
:username => 'your-user',
:password => 'your-password',
:encoding => 'utf8',
:host => host )


#------ Declaramos las clases para mapear las tablas --------
class Inicio < ActiveRecord::Base
      set_table_name :inicio
end

class Palabra < ActiveRecord::Base
set_table_name :palabras
has_many :significados
end

class Significado < ActiveRecord::Base
set_table_name :significados
belongs_to :palabra
end


puts "Cargando palabras..."
@contador=0
@inicio= Inicio.find(:all)
@inicio.each do |inicio|
@palabra = Palabra.create(:palabra => inicio.palabra,
:abreviatura => inicio.abreviatura)
@contador+=1

#------------ Vinculamos los significados -------------
(1..12).each do |num|
next if inicio["significado#{num}"].nil? || inicio["significado#{num}"].empty?
@palabra.significados.create(:significado => inicio["significado#{num}"])
end
end
puts "Finalizo la carga de palabras.."
puts "Total: #{@contador}"

How to migrate MySQL backup to PostgreSQL

Hi, the first step is generate a dump with all data from your mysql database. for example. I am working in Ubuntu 8.04 Hardy Heron

cmonterrosa@dibd02:~$ mysqldump dbname > file.sql -u root -p

enter your password and mysqldump generate a file with the BD backup. then you have tu run the script to format this file.sql into postgresql valid format.

This script is available in:

http://pgfoundry.org/frs/download.php/1535/mysql2pgsql.perl

cmonterrosa@dibd02:~$ perl mysql2pgsql.perl file.sql file-pgsql.sql

where file-pgsql.sql is the file valid for introduce the schema and data into postgresql.Now we are going to restore the schema and the rows.

cmonterrosa@dibd02:~$ psql -h localhost -d diccionarios -U cmonterrosa -W 

where -h option is host, in this case is the localhost, -d is the database and -U is the owner of the database.

Comments with

Carlos Augusto Monterrosa Lopez
cmonterrosa@gmail.com / cmonterrosa@sef-chiapas.gob.mx