# Socket and servers

Source: https://libtmux.org/en/ts/latest/topics/socket-and-servers/

> Select a server socket, check liveness, and detect a replacement daemon.

A tmux server is selected by its Unix-domain socket. Use different sockets for
independent servers, such as a development session and an isolated test server.
Choose the default socket, a named socket (`-L`), or an explicit path (`-S`).

## Naming a server

`new Server()` selects the default socket. Set `socketName` to select
a named socket, or `socketPath` to use an explicit path.

```typescript
const named = new Server({ socketName: "work" });
```

Choose either a socket name or a socket path. tmux uses `TMUX_TMPDIR` to
resolve the directory for default and named sockets.

Supplying both selectors raises [`TypeError`](<https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypeError>).

## Is the server actually there?

A server handle does not prove that the target server is running. Use a liveness
check when your program needs to distinguish a live server from an unavailable
socket:

[`Server.isAlive`](<https://libtmux.org/en/ts/latest/reference/server-server-isalive/>) returns a promise of a boolean. [`Server.raiseIfDead`](<https://libtmux.org/en/ts/latest/reference/server-server-raiseifdead/>)
throws when the server is unavailable and retains the reason reported by tmux.

```typescript
if (await server.isAlive()) {
  await server.snapshot();
}
```

[`isAlive()`](<https://libtmux.org/en/ts/latest/reference/server-server-isalive/>) returns a boolean. Use [`raiseIfDead()`](<https://libtmux.org/en/ts/latest/reference/server-server-raiseifdead/>) when you need failure details.

## Killing a server, and telling two apart

Killing a server ends all its sessions. Use this only for a server your program
owns; for narrower cleanup, kill the session or pane you created.

Call [`await server.kill()`](<https://libtmux.org/en/ts/latest/reference/server-server-kill/>). [`TmuxServerRestartedError`](<https://libtmux.org/en/ts/latest/reference/errors-tmuxserverrestartederror/>) reports an operation
whose handle encountered a replacement daemon on the same socket.

A restarted server can reuse a socket path while having different state. Do
not treat a matching path as proof that a cached object still exists.