Date: Thu, 10 Jul 2008 14:15:51 +0200 From: Mel <fbsd.questions@rachie.is-a-geek.net> To: freebsd-questions@freebsd.org Cc: Anton Shterenlikht <mexas@bristol.ac.uk> Subject: Re: snippet of configure script - explain please Message-ID: <200807101415.51455.fbsd.questions@rachie.is-a-geek.net> In-Reply-To: <200807101354.46321.malcolm.kay@internode.on.net> References: <20080709172513.GA51206@mech-cluster238.men.bris.ac.uk> <200807101354.46321.malcolm.kay@internode.on.net>
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On Thursday 10 July 2008 06:24:46 Malcolm Kay wrote:
> > 9255 if { as_var=$as_ac_var; eval "test \"\${$as_var+set}\" = set"; };
> > then
>
> I find this line somewhat strange as I've not been able
> to find documentation for the expansion of ${parameter+set} under the
> Bourne shell. (nor bash, nor ksh)
> *****************************************************
> Presumably someone out there knows where to find it?
> *****************************************************
It's shorthand for ${paramter:+set}, so if unset, you get "", otherwise you
get "set":
$ echo ${foo+set}
$ echo ${HOME+set}
set
--
Mel
Problem with today's modular software: they start with the modules
and never get to the software part.
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