server.Server.run_shell

The command runs in tmux's own environment, not the caller's. Output lines are TmuxText because a shell can emit any bytes.

Errors

Returns an error when tmux refuses the command.

Also refuses outright on tmux 3.3, 3.3a, and 3.4, with Error::CapabilityDefective . Those releases send run-shell output into a pane's copy-mode buffer instead of to the client, and still exit zero, so the command appears to have produced nothing. Reporting an empty listing there would be a wrong answer the caller could not detect. 3.2a and 3.5 onwards are unaffected.

Cancel safety

The effect may have happened, and may still be happening. The shell command runs under the tmux server, not this dispatch, so a dropped call stops waiting for it without stopping it, and its output is lost.