Passing binding or arguments to ERB from the command line

Question

I have been playing around with erb from the command line recently. I wanted to make a dirt simple erb template, for example the following:

<%- name = "Joe"; quality = "fantastic" -%>
Hello. My name is <%= name %>. I hope your day is <%= quality %>.

This works if I run

erb -T - thatfile.erb

what I want to do is to make name and quality be passable from command line arguments, so that I could do something like:

./thatfile.erb "Bill" "super"

from the bash prompt and do the same thing.

I am aware that I could write a ruby script that would just read that template in and then use ERB.new(File.read("thatfile.erb")).result(binding), or writing the template after an END and doing likewise, but I'm looking for a more lightweight approach if it exists, because I don't want to write two files for each erb script that I create for this purpose.

score 21 · Answer 1 · answered May 04 '15 at 18:58

21

Alternatively, you can use a ruby script and load it in as a library.

# vars.rb
@hello = 'kirk'

# template.html.erb
<div><%= @hello %></div>

$ erb -r './vars' template.html.erb

answered May 04 '15 at 18:58

James Lim

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I like how this separates the data from the "logic" so to speak, and how you can simply stick to ruby. – Nicolas Mattia Apr 11 '16 at 10:07

Phlip · Answer 2 · 2018-04-26T17:08:34.543

16

I went with the BASH command-line shortcut for environmental variables.

Outside:

STUFF=foo,bar erb input.html.erb >output.html

Inside:

<%
   stuff = ENV['STUFF'].split(',')
%>

After a few minutes e-searching I determined the other solutions are all variations on "write the erb wrapper command yourself." Could be wrong, but I ain't going back.

edited Apr 26 '18 at 17:08

answered Aug 18 '13 at 20:28

Phlip

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score 15 · Answer 3 · answered Sep 24 '16 at 09:57

15

Please note that Ruby 2.2 and newer provide a much nicer solution that was implemented according to this:

erb var1=val1 var2=val2 my-template.erb

answered Sep 24 '16 at 09:57

Florin Asăvoaie

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Is there a way to handle arrays with this syntax? – Vincent De Smet May 17 '19 at 06:05
1

Use comma separated lists and split them. It only gets strings. – Florin Asăvoaie May 17 '19 at 06:06
1

This doesn't seem to work for me when the variables are referenced as @vars. Works ok without the @. – Daniel Jun 06 '19 at 07:39
1

@Daniel that's what the documentation says too :) – Florin Asăvoaie Jun 06 '19 at 07:46

score 11 · Accepted Answer · answered Jul 27 '13 at 07:40

11

If you are using unix, try following:

$ cat 1.erb
Hello. My name is <%= name %>. I hope your day is <%= quality %>.
$ (echo '<% name="Joe"; quality="fantastic" %>' && cat 1.erb) | erb

Hello. My name is Joe. I hope your day is fantastic.

answered Jul 27 '13 at 07:40

falsetru

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upgrade the `echo` to `cat input.html.erb` and you got it – Phlip Oct 20 '14 at 22:11

Passing binding or arguments to ERB from the command line

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