Rails Error: Unable to access log file. Please ensure that

log/development.log exists and is chmod 0666. The log level has been raised to WARN and the output directed to STDERR until the problem is fixed.

Resolution: 

Change the line : config.log_level = Logger::INFO

    to : config.log_level = :info

in development.rb, production.rb etc.

List Just Directories Using ls in Unix

ls -ld */

constant ActiveSupport::Dependencies::Mutex (NameError)

Problem:
.rvm/gems/ruby-1.8.7-p299@global/gems/activesupport-2.3.8/lib/active_support/dependencies.rb:55: uninitialized constant ActiveSupport::Dependencies::Mutex (NameError)

Ruby gems version 1.8.14

Resolution:

Downgrade gems. gem update --system 1.5.3

The following SSH command responded with a non-zero exit status.

Problem:

The following SSH command responded with a non-zero exit status.
Vagrant assumes that this means the command failed!

mount -t vboxsf -o uid=`id -u vagrant`,gid=`id -g vagrant` v-root /vagrant

Resolution:

1. On your Mac:
$ vagrant gem install vagrant-vbguest
Since I installed Vagrant as a package (dmg) otherwise do : gem install vagrant-vbguest
2. vagrant up

The gem will automatically install the update. If VM is already running just do : vagrant halt

Reference:

Automatically download and install VirtualBox guest additions in Vagrant

Move to the end of the file in vi

$ then A

Upgrading GIT on Ubuntu 10.04

• sudo add-apt-repository ppa:git-core/ppa
• sudo apt-get update
• sudo apt-get install git

Notes from stackoverflow. This works.

Testing Cookies

Notes from Rails Cookbook:

To fully test cookies, you need to test that your application is not only setting the cookies, but also correctly reading them when passed in with a request. To do that create Cookie object and add that to the simulated test Request object, which is setup before every test in the setup method.

Rails cookie tests : https://github.com/rails/rails/blob/master/actionpack/test/dispatch/cookies_test.rb

Securing Your Server by Closing Unnecessary Ports

I am getting rid of Rails Cookbook dead tree copy I bought in 2007. Notes that are valid for any Rails version.

$ netstat -an

will list all network daemons and the ports they are listening on. This will not show you the service name. To find out do:

$ less /etc/services

This will list the service name and the port number it is running. Diable the service based on your Linux flavor and reboot server to make sure it does not get restarted automatically on reboot.

Debugging Rails Applications

Notes from Rails Cookbook. Since the book is based on Rails 1.2 only some of the recipes are still applicable to Rails 3.2.

1. Ruby syntax checker:
     $ ruby -cw test.rb
        w - warn about questionable code
        c - check syntax

       In vim you can check the syntax quickly while editing by doing:
        :w !ruby -cw

2.  Dump environment info in views:
     <%= debug(headers) %>
     <%= debug(params) %>
     <%= debug(request) %>
     <%= debug(response) %>
     <%= debug(session) %>
     <%= debug(request.env) %>

3. Use rails any_object.to_yaml in your controller's action method.

4. Filter development logs:
    logger.warn "### something went wrong: #{obj.inspect}"

    Show only messages beginning with ### :
    $ tail -f log/development.log | grep "^###"

   This tip combined with Tagged logging feature in Rails 3.2 is powerful debugging tool.

5. Use Firebug console tab to inspect the client server interaction when making AJAX calls.

6. Use Live HTTP Headers to inspect HTTP traffic.