# Server.requireRunning()

- **Module:** Server
- **Package:** libtmux-swift
- **Language:** Swift
- **Kind:** method
- **Source:** https://github.com/libtmux/libtmux-swift/blob/254f8b2be7eb60cacc3ffcb3ea8e456784f582df/Sources/LibTmux/Navigation.swift#L307
- **Page:** https://libtmux.org/en/swift/latest/reference/server-requirerunning()/

```
Server.requireRunning()() -> ()
```

Throws unless a server is listening.

Use this when only availability matters; reads such as ``sessions()``
already throw when tmux cannot answer.

## Raises

- `TmuxError`