Bash SSL Certificate Expiration Check

check-certs.sh

#!/bin/bash
TARGETS=(
			'example.com'
			'example.net'
			'example.org'
		)
SLACK_URL='Your incoming webhook'. # 'https://hooks.slack.com/services/SOMETHING/SOMETHING ELSE'
emoji=":terminator:"
uname="CERT CHECKER"
channel="#alerts"
DAYS=7;
for TARGET in ${TARGETS[*]};
expirationdate=$(date -d "$(: | openssl s_client -connect $TARGET:443 -servername $TARGET 2>/dev/null \
                              | openssl x509 -text \
                              | grep 'Not After' \
                              | awk '{print $4,$5,$7}')" '+%s'); 
in7days=$(($(date +%s) + (86400*$DAYS)));
if [ $in7days -gt $expirationdate ]; then
    message="Certificate for $TARGET expires in less than $DAYS days"
 	payload="payload={\"channel\": \"$channel\", \"username\": \"$uname\", \"icon_emoji\": \"$emoji\", \"text\": \"${message}\"}"
	curl -m 5 --data-urlencode "${payload}" $SLACK_URL
	exit 0
else
	exit 5
fi

now for Slack!