fuzzy_uptime.rb

#!/usr/bin/ruby

# Tested on OS X Leopard only but should work
# for BSDs

start = /\{ sec = ([0-9]+),/.match(`sysctl -n kern.boottime`).captures[0]

uptime_secs = (Time.now.to_f - start.to_f).round

def seconds_to_time(seconds)
  out = []

  mins = (seconds.to_f / 60.0).floor

  if mins.to_f >= 60
    hours = (mins.to_f / 60).floor
    mins = (mins.to_f - (hours.to_f * 60.0))
  end

  if hours.to_f >= 24
    days = (hours.to_f / 24.0).floor
    hours = (hours.to_f % 24.0).floor
  end

  secs = (seconds % 60).floor

  out << "#{days.to_i} day#{days > 1 ? 's' : ''}"     unless days.nil?  or days.to_i == 0
  out << "#{hours.to_i} hour#{hours > 1 ? 's' : ''}"  unless hours.nil? or hours.to_i == 0
  out << "#{mins.to_i} minute#{mins > 1 ? 's' : ''}"  unless mins.nil?  or mins.to_i == 0

  out.join(', ')
end

puts seconds_to_time(uptime_secs)