Re: more file filtering (e::), stest, perl (Re: A question about filename generate)

On Mon, Jul 28, 2025 at 6:53 PM Bart Schaefer <[email protected]> wrote:
>
> On Mon, Jul 28, 2025 at 8:17 AM Marc Chantreux <[email protected]> wrote:
> >
> > if you read the 'FILENAME GENERATION' section from zshexpn, you'll see
> > that ^x exists, x~y exists but there is no thing such x^y.
>
> Not precisely true, as PWS mentioned.  This could perhaps be clarified
> in the manual.  You can append ^y to a pattern but x^y doesn't imply
> negation of the entirety of x, rather it means "x followed by anything
> not y".  The precedence is also a little confusing; e.g., * has higher
> precedence than ^ so
>
> % print configure*
> configure configure.ac configure.ac.orig
> % print configure*^.orig
> configure configure.ac configure.ac.orig
> % print configure^*.orig
> configure configure.ac
>
> That is, in x^y the x pattern is fully expanded and then must not be
> followed by the y pattern.

The best explanation I've come up with for ^y is this:
  ^foo is like a * that cannot expand to a string matching the pattern foo.

There's no need for x to be given, just ^foo is a valid pattern. x^y
isn't a specific pattern any more than x* is. x^y isn't logically any
different from (^y)x other than needing parentheses in the latter
case. (I'm sure you know all this, but I just wanted to clarify these
points.)

Perhaps there was a misunderstanding when Marc said "there is no such
thing x^y" where he was referring to entries in the manpage. It is of
course valid to write x^y because you can combine any of the globbing
elements however you like.

As a sidenote, ^x^y is also valid, although it is not very useful (one
"star" will always expand to the entire filename while the other
expands to the empty string, except for the case where x == y while
they are also just a single character. In the case of ^foo^foo, one
can expand to fo while the other expands to o, and the whole pattern
successfully matches foo, for example.)

-- 
Mikael Magnusson