Shell Programming and Scripting

for i in `who -s /etc/security/failedlogins|tail -100|grep "$dt"|awk '{print $1"  "$6}'`
do
a=`echo $i|wc -l`
if [ $a -gt 0 ]
then
echo $i
else
echo "There are no failed logins"
fi
done

echo "$i"

`who -s /etc/security/failedlogins | tail -100| awk -v dt=$dt ' /dt/ {print $1" "$6}'`

who -s /etc/security/failedlogins | awk '    BEGIN {i=0} 
                                            $0 ~ var {print $1" "$6; i++}
                                            END {if (i == 0) print "There are no failed logins"}' var=$dt