Incompatibility when Zsh invoked as 'sh'

Incompatibility when Zsh invoked as 'sh'

[DervishD]

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    Hello zshworkers :))

    I don't know if this is an incompatibility or just bad scripting
;)), but when running the GNU libc (version 2.2.4) 'catchsegv'
script, Zsh complains. Zsh is being invoked as 'sh' here, I'm sure of
it, at least.

    The problem is a 'case' like this (abbreviated):

    case "$1" in
        [*)  ....
            ;;
        *)   ....
            ;;
    esac

    Well, the error is the '[*' pattern, which zsh says is a 'bat
pattern'. Bash treats it as the regex 'match an opening bracket and
anything after it', but zsh doesn't.

    Assuming that zsh is running in 'sh' compatibility mode (because
it is invoked 'sh'), it shouldn't treat '[' as an special character
(the problem is that the bracket must be quoted), should it?

    If Zsh is behaving well, the GNU libc people should be told about
quoting the offending char.

    Thanks a lot :)

    Raúl

Re: Incompatibility when Zsh invoked as 'sh'

[Dan Nelson]

In the last episode (Feb 04), DervishD said:
>     The problem is a 'case' like this (abbreviated):
> 
>     case "$1" in
>         [*)  ....
>             ;;
>         *)   ....
>             ;;
>     esac
> 
>     Well, the error is the '[*' pattern, which zsh says is a 'bat
> pattern'. Bash treats it as the regex 'match an opening bracket and
> anything after it', but zsh doesn't.

couple datapoints:

ash does not complain; args starting with a bracket match the 1st case.

pdksh-5.2.14 run as sh does not complain, but only the literal argument
  [* matches.

The ash manpage, at least, explicitly allows this case:

     A left bracket ([) introduces a character class.  The end of the
     character class is indicated by a ``]''; if the ``]'' is missing
     then the ``['' matches a ``['' rather than introducing a character
     class.

I don't have a link to the new Single Unix spec at the moment; what's
it say?

-- 
	Dan Nelson
	dnelson@allantgroup.com

Re: Incompatibility when Zsh invoked as 'sh'

[Bart Schaefer]

On Feb 4, 12:13am, DervishD wrote:
}
}     Well, the error is the '[*' pattern, which zsh says is a 'bat
} pattern'. Bash treats it as the regex 'match an opening bracket and
} anything after it', but zsh doesn't.

On Feb 3,  8:51pm, Dan Nelson wrote:
}
} ash does not complain; args starting with a bracket match the 1st case.
} 
} pdksh-5.2.14 run as sh does not complain, but only the literal argument
}   [* matches.
} 
} I don't have a link to the new Single Unix spec at the moment; what's
} it say?

Anyone who registers their email address can now get the latest Single
Unix spec on line; start at http://www.unix-systems.org/version3/

The spec says:

  When unquoted and outside a bracket expression, the following three
  characters shall have special meaning in the specification of patterns:

  ?   A question-mark is a pattern that shall match any character.
  *   An asterisk is a pattern that shall match multiple characters, as
      described in Patterns Matching Multiple Characters.
  [   The open bracket shall introduce a pattern bracket expression.

It goes on:

  Section 9.3.5, RE Bracket Expression shall also apply to the pattern
  bracket expression, except that the exclamation mark character ( '!' )
  shall replace the circumflex character ( '^' ) in its role in a "non-
  matching list" in the regular expression notation. A bracket expression
  starting with an unquoted circumflex character produces unspecified
  results.

Nothing in section 9.3.5 allows for an unmatched left-bracket to match a
literal bracket.  The description of the "case" construct doesn't make
any exception to this, either.

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com

Zsh: http://www.zsh.org | PHPerl Project: http://phperl.sourceforge.net   

Re: Incompatibility when Zsh invoked as 'sh'

[Peter Stephenson]

"Bart Schaefer" wrote:
> On Feb 4, 12:13am, DervishD wrote:
> }
> }     Well, the error is the '[*' pattern, which zsh says is a 'bat
> } pattern'. Bash treats it as the regex 'match an opening bracket and
> } anything after it', but zsh doesn't.
> 
> Nothing in section 9.3.5 allows for an unmatched left-bracket to match a
> literal bracket.  The description of the "case" construct doesn't make
> any exception to this, either.

I suppose it's those shells' way of getting round the problem of treating a
single `[' as the start of a test without needing it quoted.  Zsh makes an
exception in that single case only; maybe the others make an exception for
any word starting with `['.  I certainly can't see any good reason for
changing.

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 392070


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Re: Incompatibility when Zsh invoked as 'sh'

[DervishD]

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    Hello Dan :)

>I don't have a link to the new Single Unix spec at the moment; what's
>it say?

    That the '[' introduces a pattern bracket expression. Details are
in the XBD specification (haven't look at it yet).

    Raúl

Re: Incompatibility when Zsh invoked as 'sh'

[DervishD]

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    Hello Bart :)

>Nothing in section 9.3.5 allows for an unmatched left-bracket to match a
>literal bracket.  The description of the "case" construct doesn't make
>any exception to this, either.

    That is, the bracket must be closed or quoted. I'll send a bug
report to the GNU libc people.

    Thanks for all :)

    Raúl