In this blog post, we will find the expiration date of SSL / TLS certificates of multiple websites or domains.
Create a text file with multiple domain names
Create a text file urls.txt containing multiple domains, one per line. Your file can be like this:
urls.txt
yahoo.com
google.com
attrition.org
xkcd.com
Create a shell script to find the expiration dates
Create a file, a bash script, with these contents.
expiration_dates.sh
#!/bin/bash
#
# Bash script to check SSL certificate expiration dates for a list of URLs
# Created by Arul John https://aruljohn.com
#
while IFS= read -r url; do
echo ">> Expiration date for $url"
echo | openssl s_client -servername $url -connect $url:443 2>/dev/null | openssl x509 -noout -dates | grep notAfter | sed 's/notAfter=//'
echo
done < "urls.txt"
Then, chmod it to 755.
chmod 755 expiration_dates.sh
Run the bash script
./expiration_dates.sh
Your output will be something like this:
$ ./expiration_dates.sh >> Expiration date for google.com Feb 25 15:49:26 2026 GMT >> Expiration date for yahoo.com Apr 1 23:59:59 2026 GMT >> Expiration date for bing.com Jun 14 22:38:02 2026 GMT >> Expiration date for yandex.com Feb 23 20:59:59 2026 GMT
You can refine this to alert you if the SSL certificate has expired or is nearing expiration, within 30 days, or something similar.
Conclusion
If you have used this at work or for personal use, let me know in the comments or via email. Thanks for reading!
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If you have any questions, please contact me at arulbOsutkNiqlzziyties@gNqmaizl.bkcom. You can also post questions in our Facebook group. Thank you.