#!/bin/bash

function isin()
{
org=$1
shift
if [ $# = "0" ]
then
        return 1
fi
if [ $org = $1 ]
then
        return 0
else
        shift
        #echo running isin $org $*
        isin $org $*
fi
}

then_people=$(users | tr ' ' '\n' | sort -u)
sleep 1800
now_people=$(users | tr ' ' '\n' | sort -u)

#then_people=$(echo "ag55668 so1000 aa1000 nm1000" | tr ' ' '\n' | sort -u)
#now_people=$(echo "ag55668 so1000 zz9999 ab3645" | tr ' ' '\n' | sort -u)

people_still_on=""
people_logged_off=""
people_logged_on=""

for i in $then_people
do
	if isin $i $now_people
	then
		people_still_on="$people_still_on $i"
	else
		people_logged_off="$people_logged_off $i"
	fi
done


for i in $now_people
do
        if ! isin $i $then_people
        then
                people_logged_on="$people_logged_on $i"
        fi
done

echo People still logged on: $people_still_on
echo People that logged off: $people_logged_off
echo People that logged on: $people_logged_on