Re: Shell Grammar man page

[Chet Ramey]

On 2/22/21 8:11 AM, Mike Jonkmans wrote:
> Hi,
>
> It seems some things are missing in the bash manual.
> Notably definition of command and placements of coproc- and function-definition.
>
> The section 'SHELL GRAMMAR' describes:
> - simple-command
> - pipeline
> - list
> - compound-command
> - coproc
> - function-definition

These are basically the `command' productions from the grammar. The
exception is `list', and it's there because it would be strange for
the reader if it were presented before simple commands and pipelines,
which users are more likely to encounter, even though a complete
command is technically a list.

> Simplified, a pipeline is:
>         [ ! ] command1 [ | command2 ]
>
> A list is a sequence of pipelines separated by ;, &, &&, or ||
> and optionally terminated by ;, & or NL.
>
> Within the list description, the and-list and or-list are described as:
>         and-list: command1 && command2
>         or-list: command1 || command2
> Though the text says that and/or-lists are sequences of pipelines
> (separated by && or ||).

`command1' and `command2' are meta-notation, not a grammar production.

> That is slightly inconsistent.

Not really.

> A pipeline can be reduced to a command.

In a sense, yes, depending on your definition of `command'.


> In that case, the and/or list should read:
>         and-list: pipeline1 && pipeline2
>         or-list: pipeline1 || pipeline2

No, it really shouldn't.

The bash grammar is a little messier than that POSIX grammar in
https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_10_02
but it's basically the same.

Where are you trying to go with this?

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/