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: Not listed.

Where it lives: no generic condition-poll helper found in the public library; a mwait_until exists only in the private testing component, for waiting on a spawned child process, not on tmux state

Examples¶

Use a loop with a deadline and interval when a specific wait API does not fit. Pane interaction covers output waits.

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:

mServer.signal signals a channel. mServer.wait_for waits for the channel with a timeout.

server.signal("built");
server.wait_for("built", std::chrono::seconds{5});

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.