I have no idea if time is actually passing. Obviously, I can eyeball timestamps if available, but there are times when so many lines zip through the buffer that it’s easy to lose track or even go cross-eyed.

It can be tricky to notice that lines are still being tailed if the output doesn’t drastically change in some meaningful or noticeable way. Something I like to is intercept each line and then output some kind of divider whenever n lines have been added to the buffer.

It’s as simple as:

#!/usr/bin/env bash

lines=0
while IFS= read -r line; do
	echo "${line}"
	((lines++))

	if ((lines % 5 == 0)); then
		echo "----------"
	fi
done

Effectively, all this does is:

1. Intercept each line of output being piped into the script.
2. Keep a running tally of lines we’ve intercepted so far; $lines++.
3. If the current tally is divisible by n, or in this case 5, spit out an additional line containing a divider.
4. Keep doing this forever until the process is terminated.

If you were to save this in a file named as divider.sh and set it to execute with something like chmod a+x you could test it by doing something like:

$ while true; do echo "emitting a noop"; sleep 1; done | ./divider.sh

And you’ll see something like the following:

emitting a noop
emitting a noop
emitting a noop
emitting a noop
emitting a noop
----------
emitting a noop
emitting a noop
emitting a noop
emitting a noop
emitting a noop
----------

This is pretty dumb, but now you can see that output is still being placed in your terminal buffer. I’ve set it to every 5 lines, but you can update the script to make that configurable. You could also play a sound when the script places a divider in the buffer using something like tput bel.

Anyway… Enjoy.