Command-line tool to measure how fast a file is growing?

Question

Is there a command-line tool to measure how fast a text file is growing, in units of lines/second?

For small-ish files, I can do something with watch and wc -l, but that measures the file anew each time. Usually I want to watch either a huge log file, or a pipeline.

If there was a tool that just read stdin, and every second it spat out how many newlines it had read during the past second, that'd be perfect.

It's probably pretty easy to throw something together in one of my HLLs of choice, but if there's an existing tool that does this, all the better.

Answer 1

You're looking for pv (pipe viewer), available on or at least for most unices.

data-producer | pv | data-consumer
tail -f logfile | pv -l