Errors and exceptions

A command can fail because tmux rejects it, or because the transport stops before returning a reply. Inspect the reported error and delivery state before retrying a mutation: tmux may already have received it.

For lookup failures caused by zero or multiple matches, see Filtering and queries.

A failed command, as a value¶

Command failures raise !LibTmuxException. It can carry a subcommand; its string representation includes the subcommand and stderr.

Is it safe to retry?¶

Retry a mutation automatically only when you know it was not dispatched, or when repeating it is safe for your operation. A timeout, cancellation, or dropped connection can occur after tmux has acted. These APIs expose delivery information:

Inspect the exit status after a subprocess completes. If the call was interrupted, verify the resulting tmux state before repeating a mutation.

Treat unknown delivery as potentially executed.

For subprocess calls that complete normally, inspect the exit status. If a call is interrupted or times out without a delivery state, check tmux’s resulting state before repeating a mutation.