Could not find nokogiri-1.4.4 in any of the sources on Ubuntu

If you get the error: "Could not find nokogiri-1.4.4 in any of the
sources" it is probably related to "libxm12" missing. In fact, that
library is probably there. What you are missing is the development
version:

sudo apt-get install libxml2-dev

nokogiri should then install.

Reference: Manual Install

Forcing DNS changes to take effect on Snow Leopard

I made a mistake while setting up the DNS on Linode. In order to flush the old DNS server settings. I had to run:

dscacheutil -flushcache

Then create a new zone with the right IP Address. Just ping the hostname to find the IP Address and check if it is correct by comparing it to the Linode dashboard.

How to highlight tabs in Rails

1) Include the following method in application helper.

def is_active?(page_name)
# logger.info("lllllllllllll #{page_name}")
# logger.info("cccccccccccccc #{params[:controller]}")
"current" if params[:controller] == page_name
end

2) In your layout, add this:

<%= link_to 'Articles', new_article_path, :class => is_active?("articles") %>


3) Uncomment the logger lines to see which controller is handling the request and just fill in
the parameters for is_active? method

Fixed an error from the code I found from an original post in Stackoverflow.

Installing Postgres on Snow Leopard

1) sudo port install postgresql83 postgresql83-server
2)

sudo mkdir -p /opt/local/var/db/postgresql83/defaultdb
sudo chown postgres:postgres /opt/local/var/db/postgresql83/defaultdb
sudo su postgres -c '/opt/local/lib/postgresql83/bin/initdb -D /opt/local/var/db/postgresql83/defaultdb'

3) sudo launchctl load -w /Library/LaunchDaemons/org.macports.postgresql83-server.plist

4) sudo su postgres -c '/opt/local/lib/postgresql83/bin/postgres -D /opt/local/var/db/postgresql83/defaultdb'

5) sudo vi /etc/profile

6) Add : PATH="/opt/local/bin:/opt/local/sbin:/opt/local/lib/postgresql83/bin:$PATH"

7) createuser --superuser your_macusername -U postgres

8) createdb my_database

9) sudo env ARCHFLAGS="-arch x86_64" gem install pg

10) database.yml
development:
adapter: postgresql
database: your_db
username: your_db_username

Installing pgAdmin

sudo port install pgAdmin3

Upon completion of installation, you can find the application in /Applications/MacPorts/pgAdmin3


Reference:
Installing PostgreSQL on Snow Leopard 10.6


Installing PostgreSQL on Leopard using MacPorts

No such file or directory - /tmp/mysql.sock

Fix : sudo ln -s /var/run/mysqld/mysqld.sock /tmp/mysql.sock

Reference : No such file or directory

How to customize Flash messages in Devise Rails gem

Customize the config/locales/devise.en.yml file in your project.

undefined local variable or method `confirmed_at' for

Devise Rails plugin throws this error when you don't have the

t.confirmable

in the users migration.

/etc/hosts file messed up on Snow Leopard

Whenever I run a Rails app, I had to access it via http://0.0.0:port_number. Devise Rails plugin sample app barks when redirecting with this error message:

ERROR URI::InvalidURIError: the scheme http does not accept registry part: 0.0.0:3000 (or bad hostname?)


1) To cleanup the mess, I edited the /etc/hosts file so it now looks like this:

##
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting. Do not change this entry.
##
127.0.0.1 localhost
255.255.255.255 broadcasthost
::1 localhost
fe80::1%lo0 localhost

2) Then flush the cache to pickup the new changes by running :

sudo dscacheutil -flushcache

Now you can access your local Rails apps by : http://localhost:port_number and Devise is happy again.

sudo: no tty present and no askpass program specified

When trying to deploy to a new staging server, I get the following
error:

sudo: no tty present and no askpass program specified

Solution:

Add the line: default_run_options[:pty] = true
in your deploy.rb

Installing Sphinx on Snow Leopard

1. Download sphinx-0.9.9
2. ./configure
3. make
4. sudo make install

how to get all the branches that is remote in git

If you have many remote branches that you want to fetch at once:

$ git remote update
$ git pull --all

Now you can checkout any branch as you need to, without hitting the remote repo.


http://stackoverflow.com/questions/67699/how-do-i-clone-all-remote-branches-with-git

Source code formatter for Blogspot

Very useful source code formatter for blogspot

Ruby Programming Language Book Notes 2

| operator is used for union operation in Array.
& operator is used for intersection operation in Array.

1:  class Array  
2:       def union(another)  
3:        self | another  
4:       end  
5:       def intersection(another)  
6:        self & another  
7:       end  
8:  end  

Ruby Programming Language Book Notes

1)

minimum = if x < y then x else y end

can also be written as :

minimum = x < y ? x : y

2)

class Fixnum
def inclusive(element)
self..element
end

def exclusive(element)
self...element
end
end

This eliminates the mental mapping from .. and ... to the behaviour of the methods.

3) This does not work:

class Fixnum
alias inclusive ..
alias exclusive ...
end

gives syntax error, unexpected tDOT2

So how do you redefine the .. and ...? If you do ri Fixnum, it shows the instance methods. The section on Operators has discussion on operators that can be re-defined.

Convert Haml to ERB

1) script/plugin install http://github.com/cgoddard/haml2erb.git

2) In console:
hamls = Dir["app/views/**/*.haml"] - ['app/views/layouts/screen.html.haml'];
hamls.each do |haml|
puts haml
erb = haml.sub(/\.haml$/, '.erb')
File.open(erb, 'w') do |file|
file.write Haml2Erb.convert(File.read(haml))
end
end

http://makandra.com/notes/544-convert-haml-to-erb

ERROR: There has been an error fetching the ruby interpreter. Halting the installation.

This happens when there is no network connection. How wonderful it would be if developers can give error messages that make sense! Make the code robust and give users a clear call to action to rectify any errors that they can recover from. It is surprising that even ruby gems has the same issue.

Mispelled HTTP_REFERER in Rails 3.0

The correct spelling is HTTP_REFERRER but Rails source has it with wrong spelling. So in order to get the HTTP_REFERRER do the following in your controller:

request.env["HTTP_REFERER"]

request.domain has been deprecated. The domain method has been moved to ActionDispatch::Http::URL. Ideally we want to use the method defined in this module.Do to metaprogramming it is difficult to figure out the actual keys that are used in ActionDispatch::Request. If you run this snippet:

request.env.keys.each do |x|
logger.info x
end

You will get all the keys:

action_dispatch.request.formats
action_dispatch.request.parameters
rack.session
HTTP_ACCEPT
HTTP_HOST
SERVER_NAME
rack.request.cookie_hash
action_dispatch.remote_ip
rack.url_scheme
HTTP_KEEP_ALIVE
HTTP_USER_AGENT
REQUEST_PATH
action_dispatch.request.query_parameters
action_dispatch.request.unsigned_session_cookie
SERVER_PROTOCOL
HTTP_ACCEPT_LANGUAGE
rack.errors
action_dispatch.secret_token
async.callback
REMOTE_ADDR
PATH_INFO
rack.run_once
rack.version
SERVER_SOFTWARE
action_dispatch.request.path_parameters
rack.request.cookie_string
SCRIPT_NAME
HTTP_REFERER
action_dispatch.parameter_filter
HTTP_COOKIE
HTTP_VERSION
rack.multithread
action_dispatch.request.request_parameters
action_dispatch.cookies
REQUEST_URI
rack.multiprocess
rack.request.query_hash
SERVER_PORT
HTTP_ACCEPT_CHARSET
action_controller.instance
rack.session.options
async.close
REQUEST_METHOD
warden
rack.request.query_string
action_dispatch.request.content_type
GATEWAY_INTERFACE
HTTP_CONNECTION
HTTP_ACCEPT_ENCODING
QUERY_STRING
rack.input

Now you can access any of these environment values from your controller similar to the referrer.

Accessing Webrick running on VM from Mac OS

1) If the VM is running, stop it.

2) To forward from port 3001 on the host to port 3000 on the guest, run the following command on the host.
$ VBoxManage modifyvm "Ubuntu" --natpf1 "webrick,tcp,,3001,,3000"

3) To delete the port forwarding run:

VBoxManage modifyvm "Ubuntu" --natpf1 delete "webrick"

4) Now you can go to http://localhost:3001 on your host to hit webrick running on your VM.

The page loads very slow. Is there any way to speed it up?

My Job Went to India Book Review

Businesses cannot exist without the IT and vice-versa. They are interdependent. IT systems automate the business processes and run 24 by 7. Therefore we cannot really view those who work at the “Business” level as above us. So, I disagree with the author on this point. However, he does sort of make a U turn later on in the book.

This book will make you think. For instance: What is the supply demand for programmers in a particular Business domain? This would be a good question to research so that we can plan our career.

He talks about how to survive layoffs by being knowledgeable in different areas. Not everyone wants to stay in one organization for a long time. Another thing is that it is almost impractical to learn everything in a particular technology (say, Java technology). Developers will have different intentions, for example they might have a backup plan in case of IT downturn, either by having a cash cushion or generating cash flow through software products.

I agree about following your passion. It enables us to transcend limitations. It inspires us and makes us reach a level of performance that amazes us. This explains the previous paragraph (which sounds like excuses).

Another principle that he explains - “Be the Worst” is very real. Two projects, one early in my career where I had the opportunity to work with a strong and talented team of developers and project manager. Recently when I found working for people who were not anywhere near my capabilities, they did affect my performance.

This book helps to see and expect what the work environment could possibly bring us and what we can do to proactively handle these situations.

Maintenance is seen as a menial work and recruiters downplay any experience on it. Oh, this is a developer job… Chad advises you to learn to love maintenance.

He recommends having a mentor and I am glad I read his book. I know mentors can also come in the form of a book!!! You can have more than one mentor.

I love the Eight-Hour Burn concept. This explains why I get very depressed and productivity drops during the last few weeks of the project. Now I know how to make the work stay in the office. No more nagging problems following me home!

The concept of “Presence” is very realistic. I learned this by making mistakes in the workplace and the cost was high. I wish I had read this book early in my career. Lot of things that he explains has already happened to me in my career. Still I was able to learn how to handle those situations successfully next time around.

Reading open source code really helps to solve recurring problems quickly. I have experienced this in my job. The cover of this book really needs to be improved. The content of the book is much better than the quality of cover image.

Search recursively for a specific pattern in directory and list the names of the files that has that string

grep -r "#{" .

This will search for the pattern #{ in the current directory and all the files at and below this directory