linux-kernel - RE: [PATCH 1/2] ld-version: use /usr/bin/env awk for shebank

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Date:   Wed, 9 Dec 2020 22:03:04 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Dominique Martinet' <asmadeus@...ewreck.org>,
        Vincenzo Frascino <vincenzo.frascino@....com>
CC:     Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        "linux-kbuild@...r.kernel.org" <linux-kbuild@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>
Subject: RE: [PATCH 1/2] ld-version: use /usr/bin/env awk for shebank

From: Dominique Martinet
> Sent: 09 December 2020 17:43
> 
> I've suggested either just reverting this (I'll keep my local
> workaround) or going through /bin/sh which is always safe like the
> following patch -- leaving this to maintainers.
> 
> Thanks!
> -----
> From d53ef3b4c55aa2ea5f9ae887b3e1ace368f30f66 Mon Sep 17 00:00:00 2001
> From: Dominique Martinet <asmadeus@...ewreck.org>
> Date: Wed, 15 Jul 2020 16:00:13 +0200
> Subject: [PATCH] ld-version: use /bin/sh then awk for shebank
> 
> /usr/bin/awk is not garanteed to exist (and doesn't on e.g. nixos),
> using /bin/sh and invoking awk to have it look in PATH is more robust.
> 
> Signed-off-by: Dominique Martinet <asmadeus@...ewreck.org>
> 
> diff --git a/scripts/ld-version.sh b/scripts/ld-version.sh
> index f2be0ff9a738..02dbad7b5613 100755
> --- a/scripts/ld-version.sh
> +++ b/scripts/ld-version.sh
> @@ -1,11 +1,11 @@
> -#!/usr/bin/awk -f
> +#!/bin/sh
>  # SPDX-License-Identifier: GPL-2.0
>  # extract linker version number from stdin and turn into single number
> -       {
> +awk '{
>         gsub(".*\\)", "");
>         gsub(".*version ", "");
>         gsub("-.*", "");
>         split($1,a, ".");
>         print a[1]*100000000 + a[2]*1000000 + a[3]*10000;
>         exit
> -       }
> +}'

Why bother with awk?
I think you can do it all in a shell function.
Something like:
	read line
	line=${line##*)}
	line=${line##*version }
	IFS='.-'
	set $line
	echo $(($1*100000000 + $2*1000000 + $3*10000))

That will work on any recent shell.

	David

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