linux-kernel - Re: [PATCH] scripts/gen-btf.sh: fix shebang for NixOS

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Message-ID: <ea83b91a-796c-4329-bcf5-2c49efa897fc@t-8ch.de>
Date: Tue, 20 Jan 2026 20:38:59 +0100
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Gary Guo <gary@...yguo.net>
Cc: Ihor Solodrai <ihor.solodrai@...ux.dev>, 
	Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, 
	Andrii Nakryiko <andrii@...nel.org>, Martin KaFai Lau <martin.lau@...ux.dev>, 
	Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>, 
	Yonghong Song <yonghong.song@...ux.dev>, John Fastabend <john.fastabend@...il.com>, 
	KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>, 
	Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>, bpf@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] scripts/gen-btf.sh: fix shebang for NixOS

On 2026-01-20 19:15:11+0000, Gary Guo wrote:
> On Tue Jan 20, 2026 at 6:59 PM GMT, Ihor Solodrai wrote:
> > On 1/20/26 10:20 AM, Gary Guo wrote:
> >> From: Gary Guo <gary@...yguo.net>
> >> 
> >> NixOS only puts /usr/bin/env and /bin/sh at the standard location as
> >> required by POSIX, but not other shells. Other program that kernel build
> >> depends on is supplied via PATH, so shebang needs to use /usr/bin/env to
> >> find them.
> >> 
> >> This has been done to a few other scripts already, e.g.
> >> gen_test_kallsyms.sh or decode_stacktrace.sh.
> >> 
> >> Fixes: 522397d05e7d ("resolve_btfids: Change in-place update with raw binary output")
> >> Signed-off-by: Gary Guo <gary@...yguo.net>
> >> ---
> >>  scripts/gen-btf.sh | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >> 
> >> diff --git a/scripts/gen-btf.sh b/scripts/gen-btf.sh
> >> index be21ccee3487..4cd3159f2ddb 100755
> >> --- a/scripts/gen-btf.sh
> >> +++ b/scripts/gen-btf.sh
> >> @@ -1,4 +1,4 @@
> >> -#!/bin/bash
> >> +#!/usr/bin/env bash
> >>  # SPDX-License-Identifier: GPL-2.0
> >>  # Copyright (c) 2025 Meta Platforms, Inc. and affiliates.
> >>  #
> >> 
> >> base-commit: 053966c344dbd346e71305f530e91ea77916189f
> >
> > Hi Gary, thanks for the patch.
> >
> > I'm guessing this came up because gen-btf.sh is part of the vmlinux
> > build, and link-vmlinux.sh has #!/bin/sh (not bash).
> 
> My typical experience is that when I see an error about /bin/bash not found, I
> just use "bash <script path>" instead without putting much think into it.
> 
> gen-btf.sh is part of build so I don't get to invoke the script directly, hence
> the patch.

For the build we have $(CONFIG_SHELL) to stick before the script.
It is only 'sh', but it is the well-known variable users know to
override. IMO all script invocations should use this mechanism.


Thomas