How do I suppress unwanted dollar and quote symbols when using "printf %q"?

Question

I need to escape the newline characters in a public key in order to embed it within json output from within a bash script. What I want to do is this:

Little-Net:~ minfrin$ [escape-it-somehow] server.pub"
-----BEGIN PUBLIC KEY-----\nMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAqczXmXuynhalcmzP7ebV\nd7RYLLKJlGLT3OGL5VMnttvPRWoYGueseXnwlHKOcEYv0ZdSVi+e+yWK0lVgARQ9\nkNdumatV9h1S7IHC8fFexuz32Pu7piZlIcsRR+wSWXyA53KPT3NahlLqUGzQ66WX\nGqNmvcJjY0YcaPYjDsueTuQK3wogGOYrVetI33nVX/1ckBbtjgAjf8Bpieb2SQ1Z\nJYt+iBE4h7shUrRT9kT7+8BpGuZgUTVYFSxRw9r6TaFrLyaImRCELTqrxILSHWcz\nJtYBzyYFjYzENNn5L4fcrDFIId5oNil3ZaDtDFNdekdyOdirSHC3J7+aHbYKnC8a\nWwIDAQAB\n-----END PUBLIC KEY-----

I have tried to use the bash printf function, but for reasons I do not understand the output is surrounded by a dollar and quote characters like so:

Little-Net:~ minfrin$ printf %q "$(cat server.pub)"
$'-----BEGIN PUBLIC KEY-----\nMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAqczXmXuynhalcmzP7ebV\nd7RYLLKJlGLT3OGL5VMnttvPRWoYGueseXnwlHKOcEYv0ZdSVi+e+yWK0lVgARQ9\nkNdumatV9h1S7IHC8fFexuz32Pu7piZlIcsRR+wSWXyA53KPT3NahlLqUGzQ66WX\nGqNmvcJjY0YcaPYjDsueTuQK3wogGOYrVetI33nVX/1ckBbtjgAjf8Bpieb2SQ1Z\nJYt+iBE4h7shUrRT9kT7+8BpGuZgUTVYFSxRw9r6TaFrLyaImRCELTqrxILSHWcz\nJtYBzyYFjYzENNn5L4fcrDFIId5oNil3ZaDtDFNdekdyOdirSHC3J7+aHbYKnC8a\nWwIDAQAB\n-----END PUBLIC KEY-----'

My question is, why are the dollar and the quote characters added by printf? How do I stop printf from adding the dollar and quote symbols? Is there another technique I should be using instead of printf to escape a newline character?

This is bash as provided by MacOSX 10.10.5. I get the same result from bash as supplied by CentOS6.

Answer 1

You may use awk for escaping:

awk -vRS="\n" -vORS="\\\n" '1' server.pub