John123 John123 - 5 months ago 29
Ruby Question

Learning Ruby ERB Templates

I'm trying to learn Ruby ERB Templates using the following guide:
Tutorial Link

I am on the "very simple example" section with the following code:

require 'erb'

weekday ='%A')
simple_template = "Today is <%= weekday %>."

renderer =
puts output = renderer.result()

I wanted to run this code to generate an html file so I created a file called


and ran the code with the following command:

erb testing.html.erb > new-file.html

When I did that through the terminal several errors popped up and the html file that was generated was blank. Here are the errors that I received:
enter image description here

I was hoping someone could tell me what i was doing wrong. Am I forgetting something? Or am I not running the erb command correctly? Any help would be greatly appreciated. Thanks!


The code will run if you pass it to ruby. That is initiate it with this:

ruby testing.html.erb > new-file.html

The erb command expects to be passed an erb template file and not a piece of ruby code. It sees all the ruby code as just plain text, with just the insertion code <%= weekday %> needing to be interpreted as ruby code. So it tries to interpet weekday - but as it hasn't been defined it fails.

Try this and I think you may see what's happening:

Change the content of the file 'testing.html.erb' to:

require 'erb'

weekday ='%A')
simple_template = "Today is <%= %>."

renderer =
puts output = renderer.result()

Then look at the output of erb testing.html.erb:

require 'erb'

weekday ='%A') simple_template = "Today is 2016-10-24 08:40:41 +0100."

renderer =

Note that the whole file 'testing.html.erb' is the template.

Now look at the output of ruby testing.html.erb

Today is 2016-10-24 08:42:16 +0100.

Here the template is the content of the variable simple_template