get-tls-certificate-expiration-date-for-host.sh

#!/bin/bash

function get_TLS_certificate_expiration_date_for_host() {
    local host="${1}"
    local port="${2}"

    if [ -z "${host}" ];
    then
        echo 'A non-empty host is required as first argument.'

        return 1;
    fi

    if [ -z "${port}" ];
    then
        port=443
    fi

    local command='echo | openssl s_client -servername '"${host}"' -connect '"${host}"':'"${port}"' 2> /dev/null'
    command="$command"' | openssl x509 -noout -enddate'

    if [ ! -z "${DEBUG}" ];
    then
        echo '=> About to execute "'$command'"'
    fi

    /bin/bash -c "${command}"
}

alias get-TLS-certificate-expiration-date-for-host='get_TLS_certificate_expiration_date_for_host'

## From the command-line 
#$ get-TLS-certificate-expiration-date-for-host thierry.marianne.io
#
# Copyright (C) 2024  Thierry Marianne <github.6whk7@filtrable.simplelogin.com> -- assert_monitored_domains_are_available.sh
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.