POSIX character classes (was Re: pipes and sub-shells)

[Thorsten Glaser]

Martijn Dekker dixit:

>* BUG_NOCHCLASS: POSIX-mandated character [:classes:] within bracket
>[expressions] are not supported in glob patterns.

I really really REALLY hate that this will make mksh really big.
We’re talking about 36K .rodata even without titlecase conversion
and BMP-only (16-bit Unicode) here.

Can I get by making them match ASCII only even in UTF-8 mode?

Strictly speaking, POSIX requires only support for the C locale,
and our UTF-8 mode is only close to POSIX anyway, and currently
(though this will change, there have been good points made for
locale tracking) enabled using a mksh-specific set flag.

If I implemented that, we could then say that “lksh -o posix”
is, in the C locale, fully POSIX conformant. (Perhaps — but
certainly a goal to work for, even despite the uselessness
of standards.)

bye,
//mirabilos
-- 
(gnutls can also be used, but if you are compiling lynx for your own use,
there is no reason to consider using that package)
-- Thomas E. Dickey on the Lynx mailing list, about OpenSSL

Re: pipes and sub-shells

[Martijn Dekker]

Op 23-03-17 om 10:49 schreef Jean Delvare:
> Apparently it requires a more recent version of mksh than we are
> shipping:
> 
> $ echo $KSH_VERSION
> @(#)MIRBSD KSH R50 2014/06/29 openSUSE

That version is quite ancient, so you should consider upgrading it to
the latest. FYI, modernish 
currently detects the following bugs on it that are relevant for
cross-shell programming. All except BUG_LNNOALIAS, BUG_LNNOEVAL and
BUG_NOCHCLASS have been fixed in the current release. The former two are
fixed in current cvs. The latter is a design decision from Thorsten that
is nonetheless a bug in POSIX terms.

* BUG_CMDPV: 'command -pv' does not find builtins.

* BUG_CMDSPEXIT: preceding a special builtin with 'command' does not
stop it from exiting the shell if the builtin encounters an error.

* BUG_CMDVRESV: 'command -v' does not find reserved words such as "if".

* BUG_LNNOALIAS: $LINENO is always expanded to 0 when used within an alias.

* BUG_LNNOEVAL: $LINENO is always expanded to 0 when used in 'eval'.

* BUG_NOCHCLASS: POSIX-mandated character [:classes:] within bracket
[expressions] are not supported in glob patterns.

* BUG_PP_01: POSIX says that empty "$@" generates zero fields but empty
'' or "" or "$emptyvariable" generates one empty field. This means
concatenating "$@" with one or more other, separately quoted, empty
strings (like "$@""$emptyvariable") should still produce one empty
field. With this bug, this erroneously produces zero fields.

* BUG_PP_02: Like BUG_PP_01, but with unquoted $@ and only with
"$emptyvariable"$@, not $@"$emptyvariable".

* BUG_PP_03: Assigning the positional parameters to a variable using
either var=$* or var="$*" or both doesn't work as expected, using either
default, empty, unset or custom settings of $IFS.

* BUG_PP_04: Like BUG_PP_03, but for a default assignment within a
parameter substitution, i.e. ${var=$*} or ${var="$*"}.

* BUG_SELECTRPL: In a 'select' loop, input that is not a menu item is
not stored in the REPLY variable as it should be.

* BUG_TESTERR0: test/[ exits successfully (exit status 0) if an invalid
argument is given to an operator.

Hope this helps,

- M.

Re: pipes and sub-shells

[Jean Delvare]

Hi Martijn,

On mer., 2017-03-22 at 10:26 +0100, Martijn Dekker wrote:
> Op 22-03-17 om 10:12 schreef Jean Delvare:
> > 
> > Concretely, the customer's code looks like this:
> > 
> > command | while read line
> > do
> > if 
> > then
> > exit
> > fi
> > process $line
> > done
> [...]
> > 
> > I was wondering if there is any other trick you can suggest that would work 
> > in mksh?
> 
> A here-string with a command substitution:
> 
> while read line
> do
>   if 
>   then
>   exit
>   fi
>   process $line
> done <<<$(command)

Apparently it requires a more recent version of mksh than we are
shipping:

$ echo $KSH_VERSION
@(#)MIRBSD KSH R50 2014/06/29 openSUSE
$ ./test_return.sh
./test_return.sh[10]: syntax error: '(' unexpected

But indeed works find with the latest upstream version, thanks for the
pointer.

Thanks,
-- 
Jean Delvare
SUSE L3 Support