linux-kernel - Re: script relative shebang

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Date:	Wed, 01 Jun 2016 09:00:10 +0100
From:	Boris <ribalkin@...il.com>
To:	Nicolai Stange <nicstange@...il.com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: script relative shebang

Hi Nicolai,

Yes, I think this is too ugly:

#!/usr/bin/gawk {exit system("/bin/sh -c 'exec \"$(dirname \"$0\")\"/subdir/catself \"$0\"' " FILENAME);}

Imagine you have that feature in your kernel would you rather use:

#!{dirname}/subdir/catself

You second advice involves changing root fs which is not desirable in copy-deployment apps (bring all the dependencies)

This more about making kernel "user" friendly.

Thank you.

On 1 June 2016 00:02:05 BST, Nicolai Stange <nicstange@...il.com> wrote:
>Hi Boris,
>
>Boris Rybalkin <ribalkin@...il.com> writes:
>
>> I would like to know if any changes to parsing '#!' script header
>line
>> are accepted in particular having ability to run interpreter from
>> relative to the script path?
>>
>> Something like:
>>
>> #!{dirname}/python/bin/python
>>
>> Where {dirname} is a special keyword replaced with dirname of a
>script.
>
>Just for the record, this can already be done without any help from the
>kernel:
>
>Assuming the following demonstration directory layout
>
>  <some_test_dir>/subdir/catself
>  <some_test_dir>/relshebang
>
>where catself.sh is your "interpreter":
>
>  #!/bin/sh
>  tail -n +2 $1
>
>and relshebang is your script file invoking the toy interpreter from
>its
>shebang as follows:
>
>#!/usr/bin/gawk {exit system("/bin/sh -c 'exec \"$(dirname
>\"$0\")\"/subdir/catself \"$0\"' " FILENAME);}
>  Hello world.
>
>
>You don't necessarily need to use gawk here, anything being able to do
>system() and taking some code snippet from its first argument will
>certainly work.
>
>If this is too ugly, you could also write your own wrapper a la
>/usr/bin/env and install that at some central location.
>
>
>Best,
>
>Nicolai

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