This is perlmonks. Where lots of people posting questions don't post full amounts of code, and lots of others have backgrounds that colour their view of the (programming) world. Assumptions are sometimes the only way questions get answered.

planetscape is correct to worry about interpolation in cases where the OP may actually be using a variable or other metacharacters. It's not in the OP's code, but, again, many petitioners post approximations of their code to try to cover up or hide mistakes or whatever (which is still a bad idea). And then we can start guessing what they really did to get the error.