returns DOMAIN\Username for user with the most time logged on

recordname_for_greatest_user.bash

#!/bin/bash - 
#===============================================================================
#
#          FILE:  recordname_for_greatest_user.bash
# 
#         USAGE:  ./recordname_for_greatest_user.bash 
# 
#   DESCRIPTION: returns DOMAIN\user for the network user with most time on system
#                * with changes to dscl this no longer works in 10.8 and maybe 10.7
# 
#        AUTHOR: Ryan Manly (), ryan.manly@gmail.com
#       COMPANY: Glenbrook High School District 225
#       CREATED: 12/14/2011 18:04:40 CST
#      REVISION:  ---
#===============================================================================


i=0
userlist=()

# read a heredoc into an array using the output from the commmand by PBUKOWINSKI tweaked a bit
# reverse the sort and don't print the top line which is the total from ac

read -a userlist <<< $(ac -p | sort -nrk 2 | awk 'NR >= NF {print $1}')

# run dscl with the first index in the array [0] and redirect stdout to a temp file so we can get the line we want later
# redirect stderr so we don't see the message from dscl
# if dscl returns success then break out of the while true loop
# dscl and break are grouped with {} so that we can properly increment i if dscl errors
# this lets us try again with the next element in the array ${userlist[1]}

while true; do
    { dscl "/Active Directory/All Domains/" -read "/Users/${userlist[$i]}" RecordName > /tmp/output.txt  2> /dev/null && break; } || ((i++))
done

# get line 5 from output.txt, sub leading spaces, print, and exit because we don't need to operate on lines 6-NF
# line 5 of my output from dscl command above has the DOMAIN\username format d'Entremont was looking for

awk 'NR==5 { sub(/^[ ]+/, ""); print; exit }' < /tmp/output.txt

rm /tmp/output.txt