Re: Bash Reference Manual Type

[Dennis Williamson]

On Fri, Mar 31, 2023, 2:47 PM Martin Schulte <gnu@schrader-schulte.de>
wrote:

> Hi Chet!
>
> > >> Thanks for the report. The synopsis should read
> > >>
> > >> cd [-L|[-P [-e]]] [-@] [dir]
> > >           ^       ^
> > > But aren't these two brackets just superfluous?
> >
> > -L and -P are mutually exclusive, and -e is valid only when -P is
> > supplied.
>
> Yes, my feeling was just that | has such a low precedence that the marked
> pair of brackets could be omitted, like in
>   id|cut -c1-3
> or in the ERE
>   ^(-L|-P( -e)?)?$
>
> But situation seems to be different here.
>
> Best regards,
>
> Martin
>


This isn't regex. It's a command synopsis using a long standing notation
style. You can see it set out in POSIX in
https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap12.html#tag_12

You'll see this used in many man pages, usage messages and other
documentation. It's by no means specific to Bash.