X-Recipient:	archive-cygwin AT delorie DOT com
DomainKey-Signature:	a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:subject:to:references:from:message-id:date
	:mime-version:in-reply-to:content-type
	:content-transfer-encoding; q=dns; s=default; b=F10+G170kXltTXhu
	NVMKkUjVrHao4tcXI/sYl9GtLv3sUwWkHIyQ7F4YT4JLgPHyejC4xm+Kli1hZ06f
	bygmSWMFxuIDgC8sr3VtsRLpP7CE7Uqg0WOmp87p56iwK5MAuImANp8SONU/LNZ7
	HajLjk9Yhg3zewIL5FNP0M5u290=
DKIM-Signature:	v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:subject:to:references:from:message-id:date
	:mime-version:in-reply-to:content-type
	:content-transfer-encoding; s=default; bh=rMvaTbhoZnqfyuSsFPTF8D
	d+o5g=; b=Rjd0jthP9dUutZ0ruTJjetxrqfOXhCtgpXkaG5WC71gvbp9YTBMvn9
	8nY1vI5d86zUOpodN3ZcsD9dwOYhTShyb67HIntRgbIymAoFeAY66ZfGvwCb0UJL
	M0H9epdP97ScwWu6mBoH4OSM4ygvp4iIbfAWixWSL2bdTnWcBv/wk=
Mailing-List:	contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Id:	<cygwin.cygwin.com>
List-Subscribe:	<mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive:	<http://sourceware.org/ml/cygwin/>
List-Post:	<mailto:cygwin AT cygwin DOT com>
List-Help:	<mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender:	cygwin-owner AT cygwin DOT com
Mail-Followup-To:	cygwin AT cygwin DOT com
Delivered-To:	mailing list cygwin AT cygwin DOT com
Authentication-Results:	sourceware.org; auth=none
X-Virus-Found:	No
X-Spam-SWARE-Status:	No, score=-0.9 required=5.0 tests=BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RCVD_IN_DNSWL_NONE,RP_MATCHES_RCVD autolearn=no version=3.3.2 spammy=adapted, HX-HELO:sk:mailout, H*MI:sk:ae107c0, H*i:sk:ae107c0
X-HELO:	mailout03.t-online.de
Subject:	Re: Use a default path in exec*p*() if PATH is unset?
To:	cygwin AT cygwin DOT com
References:	<d1bc1cea-2438-5e03-e84c-8d4e169d9592 AT t-online DOT de> <ae107c01-bea2-b562-1bc6-f5ba188eeba9 AT towo DOT net>
From:	Christian Franke <Christian DOT Franke AT t-online DOT de>
Message-ID:	<7b94712a-465d-421b-bc76-720e443708d3@t-online.de>
Date:	Tue, 11 Apr 2017 13:10:49 +0200
User-Agent:	Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Firefox/52.0 SeaMonkey/2.49
MIME-Version:	1.0
In-Reply-To:	<ae107c01-bea2-b562-1bc6-f5ba188eeba9@towo.net>
X-IsSubscribed:	yes

Thomas Wolff wrote:
> Am 10.04.2017 um 22:29 schrieb Christian Franke:
>> A few years after https://cygwin.com/ml/cygwin/2014-09/msg00204.html
>> I found another use case of an unset PATH variable:
>>
>> The configure script from mandoc (http://mdocml.bsd.lv/) uses this 
>> interesting approach to query default CC command from make:
>>
>> CC=`printf "all:\\n\\t AT echo \\\$(CC)\\n" | env -i make -sf -`
> Why does it `env -i` at all?

I guess because make result should not depend on environment. I agree 
that 'env -i' is probably to much, 'env -u CC' would be enough.


> (And why does it prepend a \ to the output?)

It doesn't. The extra \\ is required because `...` is used instead of 
$(...):

$ printf "all:\\n\\t AT echo \\\$(CC)\\n"
all:
         @echo \$(CC)

$ CC=$(printf "all:\\n\\t AT echo \\\$(CC)\\n" > /dev/tty)
all:
         @echo \$(CC)

$ CC=`printf "all:\\n\\t AT echo \\\$(CC)\\n" > /dev/tty`
all:
         @echo $(CC)


> It seems this scriptlet has an issue, rather than adapting core 
> behaviour for it.

Of course Cygwin shouldn't be adapted solely for this single case.
But it possibly Cygwin should be adapted to the existing practice of 
various other open source *ix systems.

Interestingly the approach in newlib/libc/posix/execvp.c differs from 
Cygwin and others:
execvp() with PATH unset calls execv(). This has the same effect as 
execvp() with PATH set to current directory only.

Christian


--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple

- Raw text -