Tip: Shell/cron script to remedy weird MariaDB connection problem

Hi!

I wrote simple shell script being invoked from cron (each min), which monitors weird problem on ISPConfig 3/Debian Stretch - dovecot and postfix loosing connection with MariaDB db for user authentication at random intervals (while MariaDB is 100% OK). Script writes logs in /var/log if any problem detected.

Code:

# nano /etc/crontab
# run every 1 minute. Edit your script path...
# * * * * * root /home/andrei/scripts/anvcheck_services.sh

Code:

#!/bin/bash

NOW=$(date +'%Y-%m-%d %T')
LOGFILE='/var/log/anvcheck_services.log'
MAILERRLOG='/var/log/mail.err'

# Create log file if it doesn't exist.
if [ ! -f $LOGFILE ]; then
    touch $LOGFILE
    echo "$NOW : log file created" >> $LOGFILE
fi

if [ ! -f $MAILERRLOG ]; then
    exit 0
fi

ERRSTRING1="dovecot/|lda\|Fatal\|Internal\|error\|occurred"
ERRSTRING3="postfix/|smtpd\|fatal\|no\|SASL\|authentication\|mechanisms"

cat $MAILERRLOG | \
while read LINE
do
    echo "$LINE" | grep -q "$ERRSTRING1"
    if [ $? = 0 ]
    then
        echo "$NOW : Dovecot problem detected, restarting service" >> $LOGFILE
        service dovecot restart
        mv $MAILERRLOG "$MAILERRLOG-$NOW"
        exit 0
    fi
done

cat $MAILERRLOG | \
while read LINE
do
    echo "$LINE" | grep -q "$ERRSTRING3"
    if [ $? = 0 ]
    then
        echo "$NOW : Postfix problem detected, restarting service" >> $LOGFILE
        service postfix restart
        mv $MAILERRLOG "$MAILERRLOG-$NOW"
        exit 0
    fi
done