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Date: Mon, 4 Apr 2016 02:05:33 +0300
From: Andrey Repin <anrdaemon AT yandex DOT ru>
Reply-To: cygwin AT cygwin DOT com
Message-ID: <1564992119.20160404020533@yandex.ru>
To: Yaakov Selkowitz <yselkowitz AT cygwin DOT com>, cygwin AT cygwin DOT com
Subject: Re: How to install a custom permanent postinstall handler?
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References: <838469265 DOT 20160401235308 AT yandex DOT ru> <87a8lcicxg DOT fsf AT Rainer DOT invalid>   <5700975A DOT 3070002 AT cygwin DOT com> <87y48vqkfx DOT fsf AT Rainer DOT invalid>  <57015B97 DOT 3010401 AT cygwin DOT com>
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Greetings, Yaakov Selkowitz!

> On 2016-04-03 01:24, Achim Gratz wrote:
>> Yaakov Selkowitz writes:
>>> I am not in favour of /bin/sh being alternatives-able.
>>
>> I'd posit that it should not be bash then and somwone else might
>> reasonably want a different /bin/sh, perhaps even bash.  Which is
>> exactly why the alternatives system exists.

> Unfortunately the reality is that not all #!/bin/sh scripts are 100% 
> POSIX compliant, nor am I convinced that all the possible shells are 
> interchangeable either.  Ultimately this would lead to unpredictable 
> (and difficult to support) behaviour for scripts.

>>> The *proper* course of action is to use the shebang for the script
>>> interpreter you require, i.e. /bin/dash.
>>
>> It's perfectly OK to use /bin/sh (I'd even recommend it) if all you want
>> is a POSIX shell.

> True, but the OP said "my scripts rely on ASH/DASH functionality that is 
> not present in BASH".  If you use functionality specific to a given 
> shell, then you have to shebang that shell!

I agree, of course, but in this case, I have to ask one not strictly
Cygwin-related question:
Is 'local -' a POSIX construct and/or is there a way to achieve the same
effect without using it? (Localize any shell option changes within a
function.)
Because, within my reach, Cygwin is the only system that not using DASH as
/bin/sh. Though, I may try rolling some busybox…


-- 
With best regards,
Andrey Repin
Monday, April 4, 2016 01:56:44

Sorry for my terrible english...