#!/bin/bash

if [ $# -ne 1 -a $# -ne 2 ]; then echo "Usage: $0 </path/to/ssl-dhparams.pem> [1024, 2048 or 4096]"; exit 1; fi
if [ "x$2" == "x" ]; then
   BITS=4096;
else
   if [ $2 -ne 1024 -a $2 -ne 2048 -a $2 -ne 4096 ]; then echo "Bits should be 1024, 2048 or 4096"; exit 1; fi
   BITS=$2;
fi

openssl dhparam -out $1 $BITS