[External] : Re: configure shell game

[Jan Pechanec]

On Wed, Jun 03, 2026 at 07:48:36AM +1000, Damien Miller wrote:
> On Tue, 2 Jun 2026, Darren Tucker via openssh-unix-dev wrote:
> 
> > Hi.
> > 
> > I was recently reminded of this nonsense from the Solaris /bin/sh while
> > running a regression test:
> > 
> > run test proxy-connect.sh ...
> > [...]/proxy-connect.sh: warning: line 6: `...` obsolete, use $(...)
> > [...]/proxy-connect.sh: warning: line 6: `...` obsolete, use $(...)
> > [...]/proxy-connect.sh: warning: line 15: `...` obsolete, use $(...)
> 
> I'm stuggling to understand why a shell implementer would add such a
> message. ` isn't deprecated by any standard that I'm aware of, e.g.
> SUSv8 doesn't:
> 
> https://urldefense.com/v3/__https://pubs.opengroup.org/onlinepubs/9799919799/utilities/V3_chap02.html*tag_19_06_03__;Iw!!ACWV5N9M2RV99hQ!L4WtwmDb6hnyAzL0IF-QkX-8AW7ppvB5aVq9qZShC_V3vp6AjywaFNyXzWX4G2wi9qVuY4wQ7UVsJg$ 
> 
> This seems like someone's preference that somehow got implemented as
> a warning.

That's correct, the obsoletion is only the ksh93 preference.  In the
Command Substitution section of ksh93(1), it is mentioned as:

	... In the third (obsolete) form, the string between the quotes
	is processed for special quoting characters before the command
	is executed ...

It looks it was introduced into ksh93u+ released in 2012-08-01 as I
don't see it in the previous version ksh93t from 2008-11-04.  ksh93u+
was the last stable version released by AT&T before they stopped
supporting the shell that year.

I don't see it a problem per se, if one does "ksh93 -n <script>", the
problem is if one runs ksh93 as /bin/sh as that clearly becomes
annoying.

-- 
Jan Pechanec <jan.pechanec at oracle.com>