$ cat urls.txt

www.baidu.com

$ cat cert_chk.sh

#!/bin/bash

for url in `cat ./urls.txt`

do

 END_TIME=$(echo | openssl s_client -servername $url -connect $url: >/dev/null | openssl x509 -noout -dates |grep 'After'| awk -F '=' '{print $2}'| awk -F ' +' '{print $1,$2,$4 }' )

 echo "$END_TIME $url"

 END_TIME1=$(date +%s -d "$END_TIME")

 NOW_TIME=$(date +%s -d "$(date | awk -F ' +'  '{print $2,$3,$6}')")

 DAYS_LEFT=$(($(($END_TIME1-$NOW_TIME))/(**)))

 echo "day left:"$DAYS_LEFT

# if [ $DAYS_LEFT -ge  -a $DAYS_LEFT -lt  ];

# then

#   echo "Please be advised, site $url - cert will expire in $DAYS_LEFT days ($END_TIME)" | mailx -s 'Cert Expiration Notification' -aFrom:no-reply abc@abc.com

# fi

done