Using awk (or sed) to remove newlines based on first character of next line

Question

here\'s my situation: I had a big text file that I wanted to pull certain information from. I used sed to pull all the relevant information based on regexp\'s, but each \"piece\

Answer 1

$ perl -0pe 's/\n,/,/g' < test.dat
92831,499,000,0644321
79217,999,000,5417178,PK91622,PK90755

Translation: Read in bulk without line separation, swap out each comma following a newline with just a comma.

Shortest code here!