Thanks for the suggestions!

Meanwhile I have come up with this!

It's not fast, but it does the job!

#!/usr/bin/ksh

#####
#
# Set up Global Variables
#
#####

MIN_DAYS=2
MAX_DAYS=90
DEF_GROUP="cpx"
DATECALC="<patch_to_datecalc>"

#####
#
# Preliminary Tests
#
#####

#
# Test for the correct parameters are passed or report Usage
#

case $# in

1)

NUM_DAYS=$1
SEARCH_GROUP=$DEF_GROUP
;;

2)

NUM_DAYS=$1
SEARCH_GROUP=$2
;;

*)

echo "Usage: $(basename $0) <num_days> [ <group> ]"
exit 1
;;

esac

#
# Test that the number of days passed is in range (and therefore a number)
#

if [ ${NUM_DAYS} -lt ${MIN_DAYS} ] || [ ${NUM_DAYS} -gt ${MAX_DAYS} ]
then

echo "<num_days> (${NUM_DAYS}) should be > ${MIN_DAYS} && < ${MAX_DAYS}"
exit 1

fi

#
# Test that the group name passed exists
#

grep -q "^${SEARCH_GROUP}" /etc/group

if [ $? = 1 ]
then

echo "<group> (${SEARCH_GROUP}) not found!"
exit 1

fi

#####
#
# Declare Local Functions and populate arrays
#
#####

dateformat () {

DATE_MONTH=$(echo "Jan\nFeb\nMar\nApr\nMay\nJun\nJul\nAug\nSep\nOct\nNov\nDec" | grep -n $2 | awk -F':' '{print$1}')

print "$5 ${DATE_MONTH} $3"
return 0
}

#####
#
# Start the program!!!
#
#####

SEARCH_NUM=$(grep "^${SEARCH_GROUP}" /etc/group | awk -F':' '{print$3}')

TODAY=$(dateformat $(date | awk '{print $1" "$2" "$3" "$4" "$6}'))

for i in $(grep "${SEARCH_NUM}" /etc/passwd | awk -F':' '{print$1}')
do

#
# Make sure that this user has logged in before trying to process them
#

grep -p "^${i}" /etc/security/lastlog | grep -q time_last_login

if [ $? = 0 ]
then

LOGGED_DATE=$(perl -le 'print scalar localtime shift' $(grep -p "^${i}" /etc/security/lastlog | grep time_last_login | awk '{print$3}'))
LOGGED_IN=$(dateformat ${LOGGED_DATE})

DIFF_DAYS=$(${DATECALC} -a ${TODAY} - ${LOGGED_IN})

if [ ${DIFF_DAYS} -ge ${NUM_DAYS} ]
then

typeset -L9 USER="${i}:"
typeset -R4 NUMBER=${DIFF_DAYS}
echo "${USER} ${NUMBER} days (${LOGGED_DATE})"

fi

fi

done


Of course, my AIX coding is a bit rubbish, so if anyone can see how to speed this up I would be interested.

I have used the datecalc script from this forum to perform the one date take away the other!!