Checking out a remote CVS project

Posted on 27 February 2008 by kosmas

Problem
You want to use cvs to checkout a repository from a remote server.

Solution
If you were using subversion it would be very simple to do by using the remote url.
In CVS you have to to do the following:
First find out where the cvsroot in the remote server is. We will assume for this example that is located in /usr/local/cvsroot.
Then run the following on your local linux pc:

export CVSROOT=:ext:user_name@remote_pc:/path_to_csvroot export
export CVS_RSH=ssh

You then should be able to do a checkout by typing the following and supplying your password:

cvs checkout project_name

Ruby On Rails on CentOS 4.6

Posted on 26 February 2008 by kosmas

Problem
Installing Ruby on Rails on CentOS 4.6.
The yum install ruby installs an old version of Ruby 1.8.1, but you want 1.8.6
Solution
Based on a script from uberdose

The original post is here:
http://wp.uberdose.com/2007/07/15/ruby-on-rails-on-centos-45/

  wget ftp://ftp.gnu.org/gnu/readline/readline-5.1.tar.gz
  tar xvfz readline-5.1.tar.gz
  cd readline-5.1
  ./configure --prefix=/usr/local
  make
  sudo make install

  cd ..
  wget ftp://ftp.ruby-lang.org/pub/ruby/1.8/ruby-1.8.6.tar.gz
  tar xvfz ruby-1.8.6.tar.gz
  cd ruby-1.8.6
  ./configure --prefix=/usr/local --enable-pthread --with-readline-dir=/usr/local --enable-shared
  make
  sudo make install

  cd ..
  wget http://rubyforge.org/frs/download.php/20980/rubygems-0.9.4.tgz
  tar xvfz rubygems-0.9.4
  cd rubygems-0.9.4
  sudo /usr/local/bin/ruby setup.rb
  cd ..
  sudo gem install rails --include-dependencies
  sudo gem install termios --include-dependencies
  sudo gem install mongrel --include-dependencies
  sudo gem install mongrel-cluster --include-dependencies
  sudo gem install capistrano --include-dependencies
  sudo gem install mysql -- --with-mysql-dir=/usr/

Using older Capistrano version 1.x after upgrading to Capistrano 2.x

Posted on 14 February 2008 by kosmas

Problem
You have just upgraded your Capistrano installation to version 2.x, but you didn’t have time to convert your recipes to the newer version.

Solution
In order to be able to use your old recipes of Capistrano version 1.x after upgrading, you can use the following (assuming your version 1.x is 1.4.1):

cap _1.4.1_ deploy

or, if you have migrations you want to use:

cap _1.4.1_ deploy_with_migrations

Password – less logins and aliases with ssh

Posted on 6 February 2008 by kosmas

Problem
You want to be able to login to different servers with ssh, but don’t want to be using your password every time.

Solution
We assume that you already have installed ssh and have created ssh public keys in your local machine.

Run the following in your local machine:

ssh-copy-id -i ~/.ssh/id_rsa.pub user_name@remote_host

If you want to add aliases in your bash profile so you don’t have to type the whole address of the remote host, edit your .bashrc and add:
```
alias short_name="ssh user_name@remote_host"
```
Restart your X server, or simply start a new terminal session
You should be able to login with ssh without using your password by typing in your command prompt in your local machine:
```
short_name
```

Combining multiple ps pages into a multiple page pdf file

Posted on 25 January 2008 by kosmas

Problem
You have a lot of ps files and you want to combine them into a single pdf file with multiple pages.

Solution
You can use Ghostscript:

gs -q -sPAPERSIZE=a4 -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=out.pdf in1.ps in2.ps in3.ps

using authentication with acts_as_authenticated

Posted on 18 December 2007 by kosmas

Problem
You want to use the easiest authentication method, in order to add users/permissions to your application.

Solution

Install the act_as_authenticated plugin:

script/plugin install http://svn.techno-weenie.net/projects/plugins/acts_as_authenticated

Generate controllers, models and migration:
```
script/generate authenticated user account
```

Add necessary user foreign keys in appropriate tables (ie customer in xxx_create_users.rb), plus other fields you may want to use in your user table (ie role):

create table "users", :force => true do |t|
  t.column :login, :string
  ...
  t.column :role, :string, :default => 'C'
  ...
  end
  add_column :customers, :user_id, :integer
  ...
  def self.down
    ...
    remove_column :customers, :user_id
  end

Run the migration:
```
rake db:migrate VERSION=xxx
```
Comment out from app/controllers/account_controller.rb the following:
```
include AuthenticatedSystem
```
Add it in the app/controllers/application.rb just under the class declaration.
Add in application.rb (same as above) the following just after the session section:
```
before_filter :login_required, :except => [:login, :signup, :logout]
```
Comment out the default redirection after login and put your own (ie customers): in the account_controller.rb, just before
the flash[:notice] = “Logged in successfully”.
Also add the else for the the invalid login:
```
  redirect_back_or_default(:controller => 'customers', :action => 'list')
  flash[:notice] = "Logged in successfully"
else
  flash[:notice] = "Invalid Login/Password!"
```
Change the action in the signup and logout functions in the account_controller.rb file from index to login
Add (optionally) more fields (role) in the signup page (app/views/account/signup.rhtml):
```
User role

<%= f.select :role, ['A','R','C'] %>
```
Add restrictions for displaying records depending on user logged in, by using the conditions_for_collection of the activescaffold plugin in app/controllers/customers_controller.rb:
```
def conditions_for_collection
  ['customers.user_id = (?)', current_user.id]
end
```

Add a menu page layout in app/views/layouts/_menu.rhtml:


  <% if logged_in? %>
    <% if current_user.role == 'C' %>
      <%= link_to "add user", :controller => "account", :action => "signup" %>   |  
      <%= link_to "assign customer", :controller => "users", :action => "list" %>   |  
      <%= link_to "change password", :controller => "account", :action => "change_password" %>   |  
      <%= link_to "customers", :controller => "customers", :action => "list" %>   |  
    <% end %>
    <%= link_to "logout", :controller => "account", :action => "logout" %>   |  
    <%= "Logged in as " + current_user.login %>
  <% end %>

Add the call to the menu partial in the app/views/layouts/application.rhtml, just before the div with id=main :
```
<%= render :partial => "layouts/menu"%>
```

ArgumentError (3 elements of civil date are necessary)

Posted on 3 December 2007 by kosmas

Problem
On creating a default date on a model using the after create, and by using Model.date_field = ‘2007-01-01’ we get the error ArgumentError (3 elements of civil date are necessary)

Solution
The workaround is to use:

Model.date_field = Date.civil(2007,01,01)

cap deploy_with_migrations default behaviour

Posted on 30 November 2007 by kosmas

Problem
When using cap deploy_with_migrations, the default behaviour is to deploy with the migrations in the production environment.

Solution
To change this behavior add:

set  :rails_env,  "development"

in your config/deploy.rb

Keeping uploaded files between deployments

Posted on 26 November 2007 by kosmas

Problem
You are using file_column plugin (or maybe another plugin?), to upload files in your ruby on rails application. Because the files are big you don’t want to have a different copy stored in your subversion repository for each different deployment version. You want to keep a common folder with all your uploaded files, and use it with every different deployment version.

Solution
For the example, we will have a numbers table that has two file_column uploadable columns (intro,voice_mail), with the following migration:

class CreateNumbers < ActiveRecord::Migration
  def self.up
    create_table :numbers do |t|
      t.column :customer_id, :int, :null => false
      t.column :phone_no, :string, :null => false
      t.column :intro, :string
      t.column :vmail, :string
      t.column :created_at, :datetime
      t.column :updated_at, :datetime
    end

  def self.down
    drop_table :numbers
  end
end

If you already have used cap deploy or cap setup you should have a shared folder in your deployment server.
You should copy the intro and vmail folders that should be located on your public/number folder on your local development client, on a folder called number in your development server in your shared folder.
Create a file in your local pc in lib/cap_recipes.rb:
```
Capistrano.configuration(:must_exist).load do

  desc "Keep generated uploaded files between deployments"
    task :after_symlink do
       run "rm -drf #{deploy_to}/#{current_dir}/public/number"
       sudo "ln -nfs #{shared_path}/number #{deploy_to}/#{current_dir}/public"
    end
  end
```
Be careful with the naming of the task as (at least for capistrano 1.4 that I’m using), it must have a special name as after_symlink.
Also be careful that if you try to use before_symlink, it won’t work as the current symlink won’t be setup.
In your config/deploy.rb file add at the top the following:
```
require 'lib/cap_recipes'
```
Now you should be ready to deploy your new version so:
```
svn -m "added customised capistrano recipes" commit
```
make sure that you check in your version in subversion, and then:
```
cap deploy
```
you should be able to see a link in your current/public folder called number that points to the shared/number folder that hold all the uploaded files.

Adding icons to ActiveScaffold’s actions

Posted on 16 November 2007 by kosmas

Problem
You want to replace the standard text descriptions in ActiveScaffold’s actions with your icons.