Show command execution time in shell when it takes more than five seconds.

time_to_run.sh

# Add to .bashrc or .zshrc and try it out
# $ sleep 5
# -- Runs 5 seconds

time_to_words() {
	local mod num="$1" out=""
	set -- 60 second 60 minute 24 hour 7 day 4 week 12 month

	while test $num -gt 0; do
		mod=`expr $num % $1`
		num=`expr $num / $1`
		test $mod -gt 0 && out="$mod $2`test $mod -gt 1 && echo s` $out"
		shift 2
	done
	echo $out
}

precmd() {
	CUR=`date +%s`
	RUN=`expr $CUR - ${PS_TIME-$CUR}`

	test $RUN -gt 4 && echo "-- Runs `time_to_words $RUN`" >&2

	# Capture time
	trap 'PS_TIME=`date +%s`; trap DEBUG' DEBUG
}

PROMPT_COMMAND=precmd    # for bash, zsh uses precmd directly