# Understanding the \`--\` (Double Dash) Separator in \`slnodejs run\` Commands

{% hint style="info" icon="circle-info" %}
One option for adding SeaLights to a Backend Node Server is to \*wrap\* the application's startup command with `slnodejs` , as detailed [here](https://docs.sealights.io/knowledgebase/setup-and-configuration/sealights-agents-and-plugins/node.js-agent/backend-server-application/running-backend-server#wrapper-command-using-slnodejs-run). This article is specifically relevant to anyone using that approach. \
This article is **not** relevant if you are using Preload.js or if you are adding SeaLights to a Frontend Javascript application component.
{% endhint %}

### What does `--` mean in a shell command?

A standalone `--` (double dash followed by a space) is a POSIX convention that signals **"end of options."** Everything after `--` is treated as positional arguments, not as option flags — even if those arguments start with `-`.

This is a universal convention used across virtually all CLI tools. For example:

```sh
# Deletes a file literally named "-f" (without --, rm would interpret -f as a flag)
rm -- -f

# Checks out a file named "main" (without --, git might think it's a branch name)
git checkout -- main
```

### How is `--` different from `--token` or `--labid`?

They are two entirely different constructs:

| Syntax                  | Meaning                                           | Example                                 |
| ----------------------- | ------------------------------------------------- | --------------------------------------- |
| `--option` (no space)   | A long-form option flag passed to the program     | `--token`, `--labid`, `--workspacepath` |
| `-- value` (with space) | The argument separator — marks the end of options | `-- server.js`                          |

### How does `slnodejs run` use `--`?

In a `slnodejs run` command, the `--` separator tells the Sealights agent: "I'm done passing options to you — everything that follows is the application entry point you should wrap."

```sh
exec ./node_modules/.bin/slnodejs run \
  --token "$SL_TOKEN" \
  --buildsessionidfile buildSessionId \
  --labid __SEALIGHTS_LAB_ID__ \
  --workspacepath "." \
  --useinitialcolor true \
  --useslnode2 \
  -- server.js
```

* `--token`, `--buildsessionidfile`, `--labid`, etc. are **options for `slnodejs`**.
* `--` signals that options are done.
* `server.js` is the **application entry point** that Sealights will wrap and run.

### Should I include `node` after `--`?

**No.** The Sealights agent already invokes Node.js internally. The value after `--` should only be the path to your application entry point.

**Correct:**

```sh
-- server.js
```

**Incorrect:**

```sh
-- node server.js
```

### What happens if I write `-- node server.js`?

The agent interprets `node` as the application entry point file. If the agent is active, this may appear to work in some cases. However, if the agent is disabled (e.g., due to a missing or invalid token), the fallback logic runs:

```
node <first-argument-after-->
```

Since the first argument is `node`, this becomes:

```
node node
```

Node.js then attempts to load a module called `node` from the working directory, resulting in an error like:

```
Error: Cannot find module '/your-app-directory/node'
```