linux-kernel - Re: Why use /bin/sh in kernel build system?

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Date:	Tue, 29 Apr 2008 15:27:02 -0500
From:	Mark Rustad <mrustad@...il.com>
To:	Sam Ravnborg <sam@...nborg.org>
Cc:	Timur Tabi <timur@...escale.com>,
	Roland Kuhn <rkuhn@....physik.tu-muenchen.de>,
	linux-kernel@...r.kernel.org
Subject: Re: Why use /bin/sh in kernel build system?

On Apr 29, 2008, at 11:45 AM, Sam Ravnborg wrote:

>> I read in the latest Linux Journal magazine that someone noticed  
>> that even
>> though the kernel scripts say #!/bin/sh, many of them are really  
>> bash scripts.
>> This person went through the effort of changing the script to be  
>> true 'sh'
>> scripts.  Has that code been merged in?
>
> I have no patches pending but I may have lost them.
> As I am 100% ignorant about what is bash and what is not bash  
> specialities
> I will more or less be blind when I apply them so I hope they are well
> tested.

So why use /bin/sh ever in the kernel build system? I consciously  
began using /bin/bash consistently in scripts years ago because you  
just never know what you get when you use /bin/sh. I remember  
replacing /bin/sh with /bin/bash in gcc's build system to get it to  
work on some system at some point. Life is too short to keep having to  
fight silliness like this and I can't see a valid reason why a system  
building a Linux kernel, or for that matter gcc, should not have the  
bash shell installed on it.

And on some systems, changing /bin/sh to point to /bin/bash can result  
in subtle problems with that system's environment, so that is not a  
good option. At least by using /bin/bash you know what you get and the  
dependency is then known to all.

-- 
Mark Rustad, MRustad@...il.com

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