Generate ssl-cert like snakeoil certificate

snakeoil.sh

#!/bin/bash

TARGET_CERT="/etc/ssl/certs/ssl-cert-snakeoil.pem"
TARGET_KEY="/etc/ssl/private/ssl-cert-snakeoil.key"
DHPARAM="/etc/ssl/certs/dhparam.pem"

C="KR"
ST="Seoul"
L="Yeongdeungpo-gu"
O="Alex4386 Inc."
OU="Digital Cryptography Team"

# Generating snakeoil
[[ -z $CN ]] && CN=$(hostname --short)

SUBJECT_STR=""
[[ -z $C ]] || SUBJECT_STR+="/C=${C}"
[[ -z $ST ]] || SUBJECT_STR+="/ST=${ST}"
[[ -z $L ]] || SUBJECT_STR+="/L=${L}"
[[ -z $O ]] || SUBJECT_STR+="/O=${O}"
[[ -z $OU ]] || SUBJECT_STR+="/OU=${OU}"
SUBJECT_STR+="/CN=${CN}"

openssl req -x509 -newkey rsa:4096 -keyout "${TARGET_KEY}" -nodes -out "${TARGET_CERT}" -subj "${SUBJECT_STR}" -sha256 -days 365
openssl dhparam -out "${DHPARAM}" 2048