Re: shell (/bin/sh) pattern matching bugs

[Robert Elz <kre%munnari.OZ.AU@localhost>]

    Date:        Sun, 24 Jun 2018 15:52:21 +0200
    From:        tlaronde%polynum.com@localhost
    Message-ID:  <20180624135221.GB929%polynum.com@localhost>

  | It's a mess... 

Yes...

  | Wouldn't it be simple for POSIX to let the case...esac
  | as is and introduce a ecase...esac[e] (à la grep, egrep) with something
  | making more sense for corner cases?

It might be rational for someone to do that, but it won't be posix
which simply writes down what the standard is (what users can
depend upon working) - they don't (at least most of the time)
start inventing new stuff.

In general, none of this really matters all that much - almost certainly
not enough for some shell to implement something new, and then for
it to be copied enough other places for it to be considered standard -
it is all really just corner cases that the standard has to (attempt to)
specify properly so as not to mess up the cases that people actually
use.    That's why, despite those 14 tests failing (assuming they are
testing what should happen) no real scripts actually fail.

And wrt the ps in your previous message ...

  | PS: I don't know if you have already modified the sh(1) man page

You can check at
	https://man-k.org/
which allows you to view man pages of a whole host of systems, and
versions.

What we have now about this is ...

     The syntax of the case command is

           case word in
           [(] pattern ) [ list ] ;&
           [(] pattern ) [ list ] ;;
           ...
           esac

     The pattern can actually be one or more patterns (see Shell Patterns
     described later), separated by "|" characters.

There's no explicit mention in the text of the optional '(' in the patterns
(which is in posix too) - it is a pure noise character (its presence or absense
changes nothing) - I think it was invented in ksh (the real one), and is there
simply to allow editors that indicate matching () [] {} (etc) to not get confused
by an excess number of ')'s in the file.   I use it sometimes, and omit
it other times, depending entirely on my mood at the time - and to a
degree, how long the particular case expression is likely to remain
around - if it is likely to be a stable script, I am nore likely to include
that '(' than I do in truly "one off" scripts.

kre