get cert from remote server and install it to local machine

install_cert.sh

#!/bin/sh
#
# usage: install_cert.sh remote.host.name
# aggregated from:
# - http://stackoverflow.com/questions/699576/validating-parameters-to-a-bash-script
# - https://help.ubuntu.com/community/OpenSSL
# - http://www.madboa.com/geek/openssl/#cert-retrieve

die () {
    echo >&2 "$@"
    exit 1
}

REMHOST=$1
REMPORT=${2:-443}
CERT="$1.crt"

[ "$#" -eq 1 ] || die "1 argument required, $# provided"

openssl s_client -connect ${REMHOST}:${REMPORT} 2>&1 | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' > ${CERT}

sudo cp $CERT /usr/share/ca-certificates/$CERT
sudo dpkg-reconfigure ca-certificates
sudo update-ca-certificates