Inserting newlines into text file using tr or sed or awk

[sabersong]

I've got a rather large text file, specifically a hosts file, that isn't formatted properly. It's all one line. I need to put a newline before every occurence of 127.0.0.1. I can't find a way to do it easily in Kate or LibreOffice, and I don't really understand enough about sed or awk to be able to figure it out. I tried using tr, but got varied results, some close, but none right. Most recently, I tried the example below, but it took out all the "127.0.0", and put "1" in a lot of places I didn't want it.

cat hosts | tr "127.0.0.1 " "\n127.0.0.1 " > newHosts

I'm new to this aspect of Linux, and I know I have a lot of reading to do to really understand tr and sed and awk, but can someone help me with this particular example?

[steeldriver]

sed 's/127.0.0.1/\n&/g'

maybe? 'tr' only translates a single character at a time, I think

[sabersong]

sed 's/127.0.0.1/\n&/g'

maybe? 'tr' only translates a single character at a time, I think

That did it! Thanks so much for the help.