control.ControlSender.send

A block that tmux closed with %error is a result, not an error: it is reported through BlockResult::succeeded , the same way the process API keeps a nonzero exit status as data.

The block says tmux answered the command, not that what the command asked for has happened. Almost always those are the same moment. They are not for the commands tmux answers at once and then parks this client's queue behind: `wait-for <channel>until something signals it, andrun-shellwithout-b` for as long as its shell command runs. Each reports success, neither has finished, and the next command sent waits for it however long that is. Send those through crate::Server::cmd , where the wait costs one process rather than the connection everything else on it is sharing.

Errors

Returns an error when the command cannot be written as a control-mode line, the connection has closed, or its deadline elapses while queued, being written, or awaiting a response.

Cancel safety

A command dropped while queued is never written. Once the connection has committed it, tmux may run it, and its reply is still read and discarded, so later replies stay aligned.