# libtmux::Server::expand

- **Module:** libtmux::Server
- **Package:** libtmux-cxx
- **Language:** C++
- **Kind:** method
- **Source:** https://github.com/libtmux/libtmux-cxx/blob/85e8bd603a322dc32bb8b9aeb1a72bcf36945f1d/include/libtmux/server.hpp#L278
- **Page:** https://libtmux.org/reference/cxx/libtmux-server-expand/

```
libtmux::Server::expand(format: std::string_view) -> expected< std::string, CommandFailure >
```

Ask tmux to expand a format, against no target but the server itself.

Unguarded, unlike the entity forms: there is no target here that could have gone away. A server kept alive with no sessions still answers its own fields, and answers the session-scoped ones with nothing — which is the truth about that server, not a failure to report.