Stream output limit in Bash

example-limit-stream-output.bash

#! /usr/bin/env bash

# Formatting helpers
bold() {
	printf "\033[1m%s\033[0m\n" "$*"
}

dim() {
	printf "\033[2m%s\033[0m\n" "$*"
}

stream_output() {
	local max_lines="${1:-10}"
	local buffer=()

	while read -r line; do
		buffer+=("$(dim "$line")")
		buffer_length="${#buffer[@]}"

		if ((buffer_length > max_lines)); then
			buffer=("${buffer[@]:1}")
		fi

		if ((buffer_length > 1)); then
			for ((i = 0; i < buffer_length - 1; i++)); do
				tput cuu 1
				tput el
			done
		fi

		printf "%s\n" "${buffer[@]}"
	done
}

for i in {1..20}; do
	echo "line $i"
	sleep 0.1
done | stream_output 3