What I usually do is to construct the string ... and then put it into a statement like: die "The string is '$s'"

Yup ... the poor program spits out a copy of the string as it actually is, then falls over, stone dead.   (Oops...)   The point is, now you can see for yourself exactly how Perl interpreted the string literal that you just typed in, and you can fiddle with it until it’s what you intended for it to be.

Because Perl’s handling of strings and interpolation and etc. is so powerful, there are many ways to write “a string constant that is acceptable to the compiler,” that is syntactically valid but not exactly what you meant to say.  I find that this approach is the most reliable way for me to SWIM = Say What I Mean.

(It goes without saying that you should also use strict and use warnings.)