Hi!
I believe the Bash Reference Manual is missing a key note for using "set
-o".
On the man page for "bash"
(https://tiswww.case.edu/php/chet/bash/bash.html), the following line is
present
* If *-o* is supplied with no /option-name/, the values of the current
options are printed. If *+o* is supplied with no /option-name/, a
series of *set* commands to recreate the current option settings is
displayed on the standard output.
On the corresponding section for "Set" in the Bash Reference Manual
(https://www.gnu.org/software/bash/manual/html_node/The-Set-Builtin.html),
that line of text is *not present*.
Best regards!