Format options:
  %a - The abbreviated weekday name (``Sun'')
  %A - The  full  weekday  name (``Sunday'')
  %b - The abbreviated month name (``Jan'')
  %B - The  full  month  name (``January'')
  %c - The preferred local date and time representation
  %d - Day of the month (01..31)
  %H - Hour of the day, 24-hour clock (00..23)
  %I - Hour of the day, 12-hour clock (01..12)
  %j - Day of the year (001..366)
  %m - Month of the year (01..12)
  %M - Minute of the hour (00..59)
  %p - Meridian indicator (``AM''  or  ``PM'')
  %S - Second of the minute (00..60)
  %U - Week  number  of the current year,
          starting with the first Sunday as the first
          day of the first week (00..53)
  %W - Week  number  of the current year,
          starting with the first Monday as the first
          day of the first week (00..53)
  %w - Day of the week (Sunday is 0, 0..6)
  %x - Preferred representation for the date alone, no time
  %X - Preferred representation for the time alone, no date
  %y - Year without a century (00..99)
  %Y - Year with century
  %Z - Time zone name
  %% - Literal ``%'' character

   t = Time.now
   t.strftime("Today is %m/%d/%Y")   #=> "Today is 04/29/2008"
   t.strftime("at %I:%M %p")            #=> "at 10:04 PM"

(2009-12-04 Update: This does not work with RHEL 5.4. The mysql ruby gem requires ruby 1.8.6 and RHEL 5.4 only ships with ruby 1.8.5)

Using yum install ruby and mysql. The command below does not list all the required packages, but due to dependencies, the additional packages will be installed (or should be – this is all from memory).

[bm@app3 ~]$ sudo su -
[root@app3 ~]# yum install ruby ruby-devel ruby-libs ruby-irb \
> ruby-rdoc subversion-ruby mysql-server mysql-devel
[....]

Complete the basic configuration of MySQL.
[root@app3 ~]# /sbin/chkconfig mysqld on
[root@app3 ~]# service mysqld start
[root@app3 ~]# mysql_secure_installation


Download and install RubyGems. As of the date this post was written, the latest version is 1.1.1.
[root@app3 ~]# wget http://rubyforge.org/frs/download.php/35284/rubygems-1.1.1.zip
[root@app3 ~]# unzip rubygems-1.1.1.zip
[root@app3 ~]# cd rubygems-1.1.1
[root@app3 rubygems-1.1.1]# ruby setup.rb
[root@app3 ~]# cd ..
[root@app3 ~]# rm -rf rubygems-1.1.1


Now install Rails, Mongrel, the Ruby MySQL interface, Capistrano
[root@app3 ~]# gem install rails --include-dependencies --no-rdoc --no-ri
[root@app3 ~]# gem install mongrel --include-dependencies --no-rdoc --no-ri
[root@app3 ~]# gem install mysql -- --with-mysql-config=/usr/bin/mysql_config
[root@app3 ~]# gem install capistrano --include-dependencies --no-rdoc --no-ri


Phusion’s passenger gem provides a “mod_rails” module for Apache. The installation is very straight forward.
[root@app3 ~]# gem install passenger
[root@app3 ~]# passenger-install-apache2-module


Just follow the on-screen instructions to finish the installation.

# :include example
#
@requests = Request.find(:all, :include => [:department, :status])

Using the :include option may improve performance. However, it will likely use more server memory and could potentially return a lot of data through the joins that may not even be used.