I have a website called xplosa.com and it has a valid SSL certificates and I went through bash script should be able to calculate remaining day counts to expire. I know there are plenty of alternative ways to do this job but I love to work with Ubuntu bash . BTW I'm using Ubuntu 18.04

This is my sample logic


get_the_cert_expiry_date() {
    # command to retrieve the expiry date

currentDate="$(date +%Y-%m-%d)"
count=$((currentDate - certExpDate))

echo "remaining days for expiry: ${count}"
  • Is this a right logic?
  • How to implement get_the_cert_expiry_date
  • 1
    Shouldn't be count="certExpDate-currentDate" ? – FedonKadifeli Dec 26 '19 at 8:00
  • @FedonKadifeli yes can count like that but the thing is we should get the cert expiry date . the script for get date value from a website . How to do that ? – soldier Dec 26 '19 at 9:08
  • @karlsebal Please do not abuse the system – soldier Dec 26 '19 at 9:46
  • @karlsebal This is the public community please don't spoil if you don't even know the answer – soldier Dec 26 '19 at 9:56
  • That's not work anymore I need a script to calculate remaining day counts for my SSL certificate expiry let's say today Dec 26th and my SSL certificate would expire in Dec 28th, then the output should be 2 days left . That's all – soldier Dec 26 '19 at 10:05

This should work


echo -n | openssl s_client -servername "$website" -connect "$website":443 2>/dev/null | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' > $certificate_file
date=$(openssl x509 -in $certificate_file -enddate -noout | sed "s/.*=\(.*\)/\1/")
date_s=$(date -d "${date}" +%s)
now_s=$(date -d now +%s)
date_diff=$(( (date_s - now_s) / 86400 ))
echo "$website will expire in $date_diff days"
rm "$certificate_file"
  • Output of this code tells ``` unable to load certificate 140490086364224:error:0909006C:PEM routines:get_name:no start line:../crypto/pem/pem_lib.c:745:Expecting: TRUSTED CERTIFICATE will expire in 0 days ``` – soldier Dec 27 '19 at 8:12
  • updated answer... check now @soldier – Akhil Jalagam Dec 28 '19 at 9:06
  • 1
    I suggest to add rm "$certificate_file" to clean up again. – Cyrus Apr 12 at 4:01

# Based on https://askubuntu.com/questions/1198619/bash-script-to-calculate-remaining-days-to-expire-ssl-certs-in-a-website

### Read Site Certificate and save as File ###
echo -n | openssl s_client -servername $1 -connect $1:443 2>/dev/null | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' > $1.crt

### Get Full Expiratoin Date ###
date=$(openssl x509 -in $1.crt -enddate -noout | sed "s/.*=\(.*\)/\1/" | awk -F " " '{print $1,$2,$3,$4}')

### Convert Expiration Date in Epoch Format ###
date_s=$(date -j -f "%b %d %T %Y" "$date" "+%s")

### Get Curent Date in Epoch Format ###
now_s=$(date +%s)

### Calculate Time Difference ###
date_diff=$(( (date_s - now_s) / 86400 ))

echo "Certificate for $1 will expire in $date_diff days"
  • answer seems like the same as above. it would be better to edit the accepted answer instead of adding a duplicate. @Ronen – Akhil Jalagam Apr 16 at 4:53

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