If you have control over the format of the lines you want to interpolate into, I strongly suggest using a templating module and a "stash" of variables (such as a hash) rather than scalars which can only really be interpolated by string eval.

use Mojo::Template;
my %vars = (
  var1 => 'abel',
  var2 => 'baker',
  var3 => 'charlie',
);

my $t = Mojo::Template->new(vars => 1);
my $rendered = $t->render($text, \%vars);
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There are many other options like Text::Template, Template::Toolkit, and Text::Xslate (which is designed to escape HTML by default, so you will want to configure it for type => 'text').