Comment (by Roland Haas):

Yes, it means that you can copy multiple bash commands out of the cell into eg a terminal. And as an added bonus even when (incorrectly) copying the %bash line as well then the shells just responds with:

$ %bash
bash: fg: %bash: no such job

and continues with the next line (unless, of course, someone has a background process “bash” running in that terminal in which case I assume they are advanced Unix users and know what to not copy).

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2247/updates-to-tutorial-notebook