Log file full of nulls

Setup, Configuration and Use Runtime
4

I’ve discovered what causes this as I’ve done it again.

My openHAB log file was quite big and I was trying to look at the latest entries without having to scroll through hundreds of lines.
So, I deleted the lines I didn’t need and the next time, and every subsequent time I opened the log, it was full of spaces (nulls) as well as the actual entries.

I fixed it before but I’m not sure how (it may have gone away when I updated openHAB.

It didn’t have this effect before the logging was updated a couple of months ago.

I have two questions:

  1. How do I fix it without updating openHAB (can I update just a bit)?
  2. What is the correct way of clearing out entries from the log file from time to time?

Thanks!