Category Archives: ruby

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Setting up Ruby on Rails on a Redhat Enterprise Linux Rackspace Cloud Server

1. Compile Ruby from source.

First, install all the libraries you’ll need to compile Ruby.

yum install gcc zlib libxml2-devel 
yum install gcc
yum install zlib
yum install zlib-devel
yum install openssl
yum install openssl-devel

My particular application has problems with Ruby 1.9.2, so I compiled Ruby 1.8.7 instead. This can be downloaded from ftp://ftp.ruby-lang.org/pub/ruby/1.8/ruby-1.8.7-p174.tar.gz

Unpack the source code for Ruby. Configure and install it with:

./configure
make
make install

Add /usr/local/bin to the beginning of your PATH.

2. Install Ruby Gems.

Downloadcd the latest Ruby Gems package and unpack it. I got mine from http://production.cf.rubygems.org/rubygems/rubygems-1.7.1.tgz . Change to the directory and run:

ruby setup.rb

3. Install Rails and rake

gem install rails rake

If all goes well, you should now have Rails and rake.

Troubleshooting:

*builder-2.1.2 has an invalid value for @cert_chain*

Downgrade Rubygems to version 1.6.2 with the following command.

gem update --system 1.6.2

(Stack Overflow)

sqlite3-ruby only supports sqlite3 versions 3.6.16+, please upgrade!

Compile sqlite from source:

wget http://www.sqlite.org/sqlite-amalgamation-3.7.0.1.tar.gz
tar zxvf sqlite-amalgamation-3.7.0.1.tar.gz
cd sqlite-amalgamation-3.7.0.1
./configure
make
make install
gem install sqlite3

LoadError: no such file to load – openssl

  1. Install openssl and openssl-devel.
    yum install openssl openssl-devel
    
  2. Go to your Ruby source directory and run the following commands:
    cd ext/openssl
    ruby extconf.rb
    make
    make install
    

LoadError: no such file to load – readline

yum install readline-devel

Change to your Ruby source directory and run the following:

cd ext/readline
ruby extconf.rb
make
make install

(Code snippets)

You can’t access port 80 from another computer.

Port 80 (the web server port) is blocked by default on Redhat Enterprise Linux 5.5. Edit /etc/sysconfig/iptables to allow it, adding a line like:

-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT

Make sure you put it above the REJECT all line.

Load your changes with

/etc/init.d/iptables restart

(Cyberciti)

2011-04-04 Mon 11:06

Lotus Connections Communities topics+replies feeds to OPML

Keeping track of discussions in Lotus Connections Communities can be difficult, so I thought I’d use a feed reader to read new forum topics and replies. Instead of subscribing to each community by hand, I wrote a Ruby script that generated an OPML file, which I then imported into FeedDemon. Win!

Here’s the script:

#!/usr/bin/ruby

email = ARGV[0]
password = ARGV[1]

require 'rubygems'
require 'rexml/document'
require 'open-uri'
require 'cgi'
require 'net/https'
base_url = 'https://w3.ibm.com/connections/communities/service/atom/'
url = base_url + 'communities/my'
opml = REXML::Document.new('<opml version="1.0"><head></head><body></body></opml>')
body = opml.elements['opml/body']
while url
  # Fetch the page
  $stderr.puts "Fetching " + url
  begin
    my_communities = REXML::Document.new open(url)
  rescue OpenURI::HTTPError
    begin
      my_communities = REXML::Document.new open(url, 
                                                {:http_basic_authentication => [email, password]})

    rescue OpenURI::HTTPError
      url = nil
    end
  end  
  my_communities.elements.each('*/entry') { |x|
    # Add it to the OPML
    $stderr.puts "Found " + x.elements['title'].text
    if x.elements['id'].text =~ /communityUuid=([^&]+)/
      uuid = Regexp.last_match(1)
    end
    body.add_element 'outline', {'title' => x.elements['title'].text,
      'xmlUrl' => 'https://w3.ibm.com/connections/news/atom/stories/public?source=communities&container=' + uuid
    }
  }
  # Set the URL to the next one
  url = nil
  if my_communities.elements['feed/link[@rel="next"]']
    url = my_communities.elements['feed/link[@rel="next"]'].attributes['href']
  end
  sleep 5
end
puts opml.to_s

If you want just discussion topics and replies, use this instead of the xmlUrl line above:

'xmlUrl' => base_url + 'community/forum?communityUuid=' + uuid

Ruby code to quickly convert titles to ISBNs

I love the Toronto Public Library system. I can’t say that enough. I particularly love how I can go on a reading spree, place holds on a gazillion books, and have them delivered to the library branch that’s about three blocks away from the house.

Ideally, of course, these books would arrive suitably spaced apart so that a new batch arrives just as I’ve finished another. This happens when I request popular books. Most of the time, though, the books that I want to read fall in the Long Tail–obscure titles, books that have fallen off the New York Times bestseller lists, and the occasional random find.

All of these books tend to descend on the unsuspecting library branch at the same time.

There were 27 books waiting for me earlier. The librarian thanked me for clearing the shelf. J- greatly enjoyed piling them into the shopping cart we had the foresight to bring. Yes, I’ve got presentations to prepare and things to do–but reading is fun, and I’m somehow going to find time to read all those books before my three-week loan period is up. I’ll probably be able to renew them, but hey, might as well try.

So I decided I might as well try tracking them on LibraryThing. Instead of typing in all the details manually, I grabbed the list of titles from my account on LibraryElf (good reminder system for books), used ISBNdb to convert the titles into ISBNs (best guess), and imported the list of ISBNs into LibraryThing. Now my profile lists 163 books–a small fraction of the books that have passed through my hands, but it’s better than nothing. Someday I might even get myself a barcode scanner so that I can just pick up the ISBNs from the book jackets.

Anyway, I promised the Ruby code I’d quickly written to convert the titles to ISBNs:

require 'net/http'
require 'CGI'
require 'open-uri'
require 'rexml/document' 

access_key = 'YOURACCESSKEYHERE'
while (s = gets)
  s.chomp!
  url = "http://isbndb.com/api/books.xml?access_key=" + access_key + "&index1=title&value1=" + CGI::escape(s)
  xml = REXML::Document.new(open(url).read)
  if (xml.elements["ISBNdb/BookList/BookData"])
    puts xml.elements["ISBNdb/BookList/BookData"].attributes["isbn"]
  end
end

Takes titles as standard input, prints out ISBNs. Enjoy!

Ruby

Somewhere along the way, I seem to have turned into a Ruby geek. I
spent the day converting most of my data analysis code to Ruby because
the interactivity of the Ruby shell makes prototyping so much fun. Now
if it were more like Lisp, I would be even happier. I suppose I
_could_ freak everyone out and start using Lisp – maybe Common Lisp? -
within IBM, but… =)

I still haven’t quite figured out how to use Eclipse to debug
Ruby programs. I keep getting “abnormal program termination” errors.
Ah, well, that just forces me to write programs with no bugs. ;)

On Technorati:

Random Japanese sentence: テーブルに猫の足跡が付いている。 There are footprints of a cat on the table.

Finding geeks

I don’t know why people complain about not being able to find talent.
;) I run across so many interesting people while watching mailing
lists or hanging out with other geeks. For example, if you’re looking
for Ruby geeks in the Philippines, Botp Peña sounds really interesting.
Hey, anyone who advocates Rails and volunteers training has to be cool. ;)

if you’re interested to learn ruby, i can provide training session for free. just provide the place and at least 10 people to join. dili nako kaya tudlo isa-isa. ma-luoy mo. dapat naa whiteboard (kung wala projector), mga desk/silya, printer para sa handouts/exercises, and notebooks or desktops na ma-gamit ninyo ug nako (wala koy notebook, sorry). Also, dapat naa mo programming background (any language will do. di nako gusto lurat inyo mata. dapat naka-smile pirmi). i prefer to hold trainings monthly/semi-monthly lang kay para dili kaayo ko hago. one training session will cover the whole day (puwede sab ma-hangyo half-day)

  • Peña, Botp (botp AT delmonte-phil.com)

E-Mail from Peña

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Random Japanese sentence: 私はあの店で猫を買った。 I bought a cat at that shop.

Ruby versus Java

This is totally cool. I’m in the middle of a geek crowd discussing
Java vs Ruby, but there’s none of that “my language is better than
yours” vibe that often comes out in Linux distribution discussions. I
think what’s cool about it is that most people here use both, so we’re
just figuring out where one is better than the other for something,
and how we can improve things…

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Random Japanese sentence: 彼は2匹猫を飼っている。一匹は黒でもう一匹は白だ。 He keeps two cats: one is black, and the other white.