Re: !; is interpreted as an history expansion that can never match anything

[Chet Ramey]

On 8/8/23 3:30 PM, Dale R. Worley wrote:
> Emanuele Torre <torreemanuele6@gmail.com> writes:
> > ! followed by a ; or another terminator  is interpreted as an history
> > expansion with no pattern that can never match anything.
> >
> >    $ !; echo hi
> >    bash: !: event not found
> >    $ !&& echo hi
> >    bash: !: event not found
>
> IMHO it is more to the point that in the manual page it says
>
>         !string
>                Refer  to the most recent command preceding the current position
>                in the history list starting with string.
>
> without defining "string".
>
> It looks like the actual definition is "everything from the ! to the end
> of the word", taking into account

I would have thought it obvious, since history expansion specifiers don't
span words.

>         The line is broken  into  words
>         in  the same fashion as when reading input, so that several metacharac‐
>         ter-separated words surrounded by quotes are considered one word.  His‐
>         tory  expansions are introduced by the appearance of the history expan‐
>         sion character, which is ! by default.
>
> With the significant detail that the ! need not be the first character
> of the word.

That's useful to add.

> So I think the manual page could be improved by adding *...*:
>
>         !string
>                Refer  to the most recent command preceding the current position
>                in the history list starting with string.  *All characters
>                until the start of the word designator or end of the word
>                are part of string.*

It's more general than that: the event designator is the portion of the
word from the history expansion character to a word designator or the
end of the word.

--
``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/