[ruby-on-rails] convert string to specific datetime format?

Use DATE_FORMAT from Date Conversions:

In your initializer:

DateTime::DATE_FORMATS[:my_date_format] = "%a %b %d %H:%M:%S %Z %Y"

In your view:

date = DateTime.parse("2011-05-19 10:30:14")
date.to_formatted_s(:my_date_format)
date.to_s(:my_date_format)