parse and log diagnostic information from an APC UPS

upslog.rb

#!/usr/bin/ruby

# parse and log diagnostic information from an APC UPS

require 'pp'
require 'time'

time_fields = %w{
APC
DATE
LASTSTEST
MANDATE
STARTTIME
XOFFBATT
XONBATT
}

h = {}

IO.popen('/sbin/apcaccess') do |p|
  p.read.scan(/(\w+)\s*:\s*(.*)/) do |k,v|
    v = Time.parse(v) if time_fields.include?(k)
    h[k] = v
  end
end

# pp h

# write on battery log line if it's not the same as the current last line
# of the log
open('/home/mmb/log/ups.log', 'a+') do |f|
  f.seek(0, IO::SEEK_END)

  f.seek(-2, IO::SEEK_CUR) until f.pos == 0 or f.getc == 10

  last_line = f.read

  last_batt_duration = h['XOFFBATT'] - h['XONBATT']
  new_line = "on battery #{h['XONBATT']} for #{last_batt_duration} seconds\n"

  f.write(new_line) if new_line != last_line
end