how do I get name of the month in ruby on Rails?

Ref this

<% @date = Date.today  %>  
<%= @date.strftime("%B")%>

if

@date >> Fri, 11 Jun 2010

then

@date.strftime("%B") >> "June"

If you are looking solely to the month name, the Date::MONTHNAMES constant provided by rails is the easiest solution for you:

   Date::MONTHNAMES = 
   [
    [ 0] nil,
    [ 1] "January",
    [ 2] "February",
    [ 3] "March",
    [ 4] "April",
    [ 5] "May",
    [ 6] "June",
    [ 7] "July",
    [ 8] "August",
    [ 9] "September",
    [10] "October",
    [11] "November",
    [12] "December"
   ]

If you want a localized month name, try:

I18n.t('date.month_names')[date.month]

Example:

I18n.t('date.month_names')[12] #=> "Dezembro"

If you have a particular custom date / time format which you need to use repeatedly then you can extend the ActiveSupport date / time helper.

e.g. if you define the following in your config/environment.rb

ActiveSupport::CoreExtensions::Time::Conversions::DATE_FORMATS.merge!(:full_english => "%A %B %d, %Y at %I:%M %p")

then when you call Time.now.to_s(:full_english) in your views you will get something like:

"Friday June 11, 2010 at 12:53 PM"

Ruby's strftime method is well documented at http://apidock.com/ruby/Time/strftime