Outputting to a size-restricted file
Many years ago, I worked at Bolt, Beranek & Newman, and their unix machines had a utility called "roll". I suspect it was written by them for their machines, but it was a handy utility.
Basically, if you wanted to pipe output of a program into a file, but you didn't want that file to get massive, you'd do it something like this:
myprogram | roll -f log.out -size 500k
Once the file reached 500Kb, it would start overwriting itself, keeping only the most recent 500Kb of data.
Does something like this exist on standard Linux boxes today?