linux bash user 90 day no login chshell nologin!

#!/bin/bash
today=$(date +%Y%m%d')
rbashuser=$(cat /etc/passwd |grep rbash |awk 'BEGIN {FS = ":"} {print $1}'|egrep -v "root|nike|secupang")

for user in $rbashuser
do
auser=$user
buser=$(lastlog -u $user |grep $user |awk '{print $1}')
#buser=$(lastlog -b 90 -u $user |grep $user |awk '{print $1}')
        if [ "$auser" != "$buser" ]
                then
                        echo $auser login  !!
                else
                        echo $auser nologin 90day change nologin mode !! >> /var/logs/$today-nologin.log
                        chsh -s /sbin/nologin $auser
        fi
done