generate list of variables from a properties file, for envsubst

generate-parameters-list-for-envsubst.sh

# generate list of variables from a properties file
# form : \$VARIABLE
# give it to envsubst command to avoid escaping others variable in template file
function generate-parameters-list-for-envsubst {
	type=$1
	
	local pts
	local pindex
	unset parameters
	pts=$(cat $properties|grep export|cut -d "=" -f 1|sed "s/export //g")
	declare -a plist
	pindex=0
	for p in $(echo $pts); do
	  plist[pindex]=$(echo ${p})
	  let "pindex = $pindex + 1"
	done
	parameters=""
	for s in $(seq 0 $(( ${#plist[@]} -1 )) ); do
	  [ -n "$parameters" ] && \
	    parameters=$(echo "$parameters,\\\$${plist[$s]}")
	  [ -z "$envp" ] && \
	    parameters=$(echo "\\\$${plist[$s]}")
	  #echo "Element : " ${plist[$s]}
	done
	#echo "properties : " ${parameters}
	echo -n ""
}

function update-from-template {
  properties=$1
  template=$2
  result=$3
  
	generate-parameters-list-for-envsubst "$properties"
	#echo "properties : " ${envp}

	[ -f "${template}" ] && \
		. ${properties} && envsubst ${parameters} < "${template}" | tee "${result}" > /dev/null

}