Waiting and retrying

After sending input or starting a process, wait for the state your next step requires. Pane interaction covers waiting for screen text. This page covers arbitrary conditions and tmux’s named $wait-for signal channels.

Polling a condition¶

Polling checks a condition repeatedly until it succeeds or a deadline expires. Set a deadline and choose an interval that limits unnecessary tmux commands.

Helper: mconnectedServer.waitFor(matches, options)

Where it lives: The public control-connection API. Tests a predicate over IServerSnapshot; see Control mode vs one-shot.

Examples¶

mwaitFor subscribes before reading a server snapshot so it does not miss a change between those steps.

await using live = await server.connect();
await live.waitFor((snapshot) => snapshot.windows.exists({ name: "build" }));

tmux’s own $wait-for channel¶

Use $tmux wait-for -S <channel> to signal and tmux wait-for <channel> to block until signalled. This avoids repeated screen captures when the command can announce its own completion:

The public API does not expose the channel handshake used internally by the test server during startup.

tmux remembers a signal sent before a waiter starts. The next wait on that channel returns immediately, so completion is not lost when the command finishes first.

A raw wait-for client can exit zero when the server dies, as well as when the channel is signalled. Verify server liveness when a lost server must be treated as a failed task.

Use a channel name specific to the task. A remembered signal can otherwise satisfy an unrelated later wait.