Since the answer to the original question is "This is not possible", my new question is:
How do I write a shell script, in which I can define the original bib file, the fields in which new line characters should be replaced, the string with which they should be replaced and the name of the new bib file? I feel this should be possible using automated expressions. (If this question is not sufficiently tex-related, feel free to close it.)
The idea is to run this script before I call latexmk, to still be able to substitute new line characters with the \par command automotically instead of having to do it manually each time the bib file changes (the bib file itself is already created by an automated script).
In my bibliography, the abstract and annote fields will typically be several paragraphs long. The paragraphs are separated by two newlines
I want to print a reading list using biblatex.
If I parse the bib file with biber, biber will remove all newlines and render the fields as one long line.
This is expected behaviour and apparently has been the same in bibtex.
The question is: Is there an automatic way around it? More precisely, is there a way around it short from me manually adding macros instead of newlines into the bib file.
Initially, I filed a bug report on the biber development site because I assumed it must be a bug, but Philipp Kime suggested I ask whether there is a known way around it without changing biber.