Flags are arbitrary data that you can pass to lume from the CLI. This is useful for configuration or to passing arguments to scripts. All arguments after -- are stored in the site.flags array:

lume -- first-flag second-flag

In your _config.js file you can get these two values:

console.log(site.flags[0]); // first-flag
console.log(site.flags[1]); // second-flag

Using flags in scripts

Let's say you have a script to deploy your site but you want to configure the server where your site will be uploaded:

const server = site.flags[0] || "";

site.script("deploy", `rsync -r _site/** user@${server}:/var/www/`);

Now you can run lume run deploy to deploy the site to the default server or lume run deploy -- to change the server name.

Because flags are stored in site, you can use it everywhere, for example in events:

site.addEventListener("afterBuild", () => {
  if (site.flags.includes("compress")) {