shell script to check archivelog gap between standby and primary(DG sync monitoring script)

below script can be used to find archivelog gap between primary and standby.
if shipping gap or apply gap is greater than or equal to 5 you will get mail(you can change the number if you want in if condition).


#!/bin/bash
export ORACLE_SID=ORCL
export ORACLE_HOME=`egrep -i ":Y|:N" /etc/oratab |grep $ORACLE_SID| cut -d":" -f2 | grep -v "\#" | grep -v "\*"`
export PATH=$ORACLE_HOME/bin:$PATH
DG_GAP_CHECK=`sqlplus -s "/ as sysdba" <<EOF
set pagesize 200
set linesize 121
set heading off feedback off verify off
select(select name from v\\$database) name,
(select max(sequence#) from v\\$archived_log where dest_id=1
) current_primary_seq,
(select max(sequence#)
from v\\$archived_log
where trunc(next_time)> sysdate-1
and dest_id=2
) max_stby,
(select nvl(
(select max(sequence#)-min(sequence#)
from v\\$archived_log
where trunc(next_time)> sysdate-1
and dest_id=2
and applied='NO'
),0)
from dual
) "To be Applied",
((select max(sequence#) from v\\$archived_log where dest_id=1)-
(select max(sequence#) from v\\$archived_log where dest_id=2)) "To be shipped"
from dual;
exit;
EOF`
TO_BE_SHIPPED="`echo $DG_GAP_CHECK|awk '{ print $5}'`"
TO_BE_APPLIED="`echo $DG_GAP_CHECK|awk '{ print $4}'`"
        if [ $TO_BE_SHIPPED -ge 5 ] || [ $TO_BE_APPLIED -ge 5 ]
        then
                echo $DG_GAP_CHECK | mail -r "sender@company.com" -s "`hostname`:Dataguard is out of sync" "receiver@company.com receiver@company.com"
          fi