Server, session, window, pane

libtmux models tmux’s server, session, window, and pane objects:

Server
├── Session
│   └── Window
│       └── Pane
└── Client (attached view)

A SServer contains sessions. Each SSession contains links to windows, and each SWindow contains panes. Commands run inside a SPane, where you send input and capture output. A window can be linked to more than one session.

Stable identity, not name or index¶

tmux assigns a unique ID to each session, window, and pane at creation. The ID remains stable for that object’s lifetime even if its name or index changes:

Use stable IDs to identify the same tmux object across reads. Names and indexes can change while a program is running.

Read the hierarchy:

// A snapshot reads sessions, windows, and panes in one pass; the relations
// below resolve against it without another tmux command.
let snapshot = try await server.snapshot()
for session in snapshot.sessions {
    print(session.name)
    for window in snapshot.windows(of: session) {
        print(" ", window.name)
        for pane in snapshot.panes(of: window) {
            print("   ", pane.id, pane.currentCommand)
        }
    }
}

Client: a view, not a child¶

A SClient represents a terminal attached to a session. Several clients can view the same server, and each can switch sessions or windows independently. Client fields describe the view at the time of the read.

A control-mode connection is also a client. It appears in $list-clients, counts toward #session_attached, and affects attachment-dependent behavior such as odestroy-unattached. Closing the last attached client can therefore destroy a session configured with that option.