# Socket and servers

Source: https://libtmux.org/en/go/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

[`tmux.NewServer(tmux.ServerOptions{})`](<https://libtmux.org/en/go/latest/reference/tmux-newserver/>) selects the default socket.
Set [`ServerOptions.SocketName`](<https://libtmux.org/en/go/latest/reference/tmux-serveroptions-socketname/>) for a named socket or
[`ServerOptions.SocketPath`](<https://libtmux.org/en/go/latest/reference/tmux-serveroptions-socketpath/>) for an explicit path.

```go
named, err := tmux.NewServer(tmux.ServerOptions{SocketName: "work"})
if err != nil {
    return err
}
```

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

[`ServerOptions.SocketPath`](<https://libtmux.org/en/go/latest/reference/tmux-serveroptions-socketpath/>) takes precedence over [`ServerOptions.SocketName`](<https://libtmux.org/en/go/latest/reference/tmux-serveroptions-socketname/>) when both are set.

## 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/go/latest/reference/tmux-server-isalive/>) returns `(bool, error)`. The error reports a check
that could not be completed; a false result alone means the server is not alive.

```go
alive, err := server.IsAlive(ctx)
if err != nil {
    return err
}
fmt.Println("server running:", alive)
```

## 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 [`server.Kill(ctx)`](<https://libtmux.org/en/go/latest/reference/tmux-server-kill/>) and check its error. [`server.Equal(other)`](<https://libtmux.org/en/go/latest/reference/tmux-server-equal/>) compares
the captured socket bindings, resolving relative paths and environment-based
socket names. Equal endpoints do not prove equal daemon lifetimes.
[`ErrDaemonReplaced`](<https://libtmux.org/en/go/latest/reference/tmux-errdaemonreplaced/>) reports a replacement daemon on the selected 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.