If you read the contents of the file into the variable 'var', you can 
print the evaluated string using:
    print eval var.inspect

Jim Freeze wrote:

>Hi
>Here I am again.
>
>I have a file with the line '#{a}' in it.
>I would like the variable 'a' to be evaluated
>when printed.
>
>cat t
>#{a}
>irb(main):001:0> a=5
>5
>irb(main):002:0> l=IO.readlines("t")
>["#{a}\n"]
>irb(main):003:0> puts l[0]
>#{a}
>nil
>irb(main):004:0> puts "#{a}"
>5
>
>
>How would I go about getting the #{a} to evaluate here.
>I'm trying to find a nice way for ruby to substitute
>values into variables without using regex.
>
>Thanks
>
>=========================================================
>Jim Freeze
>jim / freeze.org
>---------------------------------------------------------
>Today is a fine day for Ruby programming.
>http://www.freeze.org
>=========================================================
>