Subject: Re: Option to make cpp(1) not accept named pipes or devices as include
To: Jim Wise <>
From: Andrew Brown <>
List: tech-toolchain
Date: 11/30/2004 08:52:54
On Tue, Nov 30, 2004 at 01:54:18AM -0500, Jim Wise wrote:
>Hash: SHA1
>On Mon, 29 Nov 2004, Andrew Brown wrote:
>>>Eh?  From $PATH to $EDITOR to $TERM, lot's of programs alter their 
>>>behavior based on environment variables.
>>that's a silly argument.  :)
>>*lots* of programs use $PATH and and $EDITOR (or $VISUAL -- why are
>>there two?) or $TERM, but only cpp will use your CPP_RESTRICTED
>VISUAL and EDITOR are both around because historically programs will try 
>to use VISUAL, and fall back to EDITOR if running on a dumb terminal.  
>Of course dumb terminals are pretty rare these days.  :-)

ah, okay.  that works.  thanks for the history lesson.  :)

>More generally, it remains the case that lots of programs use 
>environment variables to cause a change in behavior -- even environment 
>variables (such as EXRC) which are only used by a single program or by 
>two closely related programs.

okay, that's true as well, but i think for EXRC it's a matter of
convenience.  adding a new command line option that i needed to use
when invoking vi would add up to thousands more characters that i had
to type every day.  otoh, i don't think i recall the last time i
invoked cpp by hand, so adding a new command line option there would
have little to no impact.

>cpp(1) itself has other variables which only it uses within our system.  
>The larger point here is that neither way is `more' unix-like.  As to 
>which way is better in this case, I've made my arguments on that matter 
>elsewhere in this thread, but I'm not particularly wedded to them.  :-)

as long as you make them both work, that should be fine.  i have to
wonder, though, why cpp would want to continue being able to read from
named pipes (etc) by default, and that perhaps the ability to do so
might be a better option.

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