Add function to substitude commands with placeholders

lsyncd.lua

@@ -3983,6 +3983,30 @@ function splitQuotedString
     return rv
 end
 
+function replaceCommand(cmd, data)
+	assert(type(data) == "table")
+	local getData = function(arg)
+		print(arg, data)
+		local rv = data[arg]
+		if rv ~= nil then
+			return rv
+		else
+			return ""
+		end
+	end
+	if type(cmd) == "string" then
+		return string.gsub(cmd, "%${(%w+)}", getData)
+	elseif type(cmd) == "table" then
+		local rv = {}
+		for i, v in ipairs(cmd) do
+			rv[i] = string.gsub(v, "%${(%w+)}", getData)
+		end
+		return rv
+	else
+		log("Error", "Unsupported type in replacCommand")
+	end
+end
+
 --
 -- Interface to inotify.
 --

tests/utils_test.lua

@@ -9,4 +9,17 @@ assert(isTableEqual(
     {"-p", "22", "-i", "/home/test/bla blu/id_rsa"}
 ))
 
+-- test string replacement
+local testData = {
+    localPort = 1234,
+    localHost = "localhorst"
+}
+assert(replaceCommand("echo ssh ${localHost}:${localPort}", testData) ==
+       "echo ssh localhorst:1234")
+
+assert(isTableEqual(
+    replaceCommand({"-p${doesNotExist}", "2${localHost}2", "-i '${localPort}'"}, testData),
+    {"-p", "2localhorst2", "-i '1234'"}
+))
+
 os.exit(0)