timeago

#!/bin/bash

minutes=60
hours=$(( 60 * minutes ))
days=$(( 24 * hours ))
diff=$(( ${2:-$(date +%s)} - $1 ))

if (( diff < 60 )); then
  ago="${diff} seconds"
elif (( diff < 120 )); then
  ago="1 minute"
elif (( diff < 1 * hours )); then
  ago="$(( (diff + minutes / 2) / minutes )) minutes"
elif (( diff < 1 * hours + 30 * minutes )); then
  ago="1 hour"
elif (( diff < 1 * days )); then
  ago="$(( (diff + hours / 2) / hours )) hours"
elif (( diff < 2 * days)); then
  ago="1 day"
else
  ago="$(( (diff + days / 2) / days)) days"
fi

echo "$ago ago"