Re: [PATCH v3 2/2] meson: prefer shell at "/bin/sh"

From: Eli Schwartz <eschwartz@gentoo.org>
Date: Apr 25, 2025, 22:21 UTC
Message-ID: <27b77b6b-d696-4837-89fe-b359ce481083@gentoo.org>
In-Reply-To: <xmqqcyd0t6qx.fsf@gitster.g>

On 4/25/25 2:51 PM, Junio C Hamano wrote:

Show 12 quoted lines

> Eli Schwartz <eschwartz@gentoo.org> writes:
>> POSIX does not require a specific absolute file path for "sh", but it
>> does mandate that you have a shell and its name is "sh", whichever
>> directory it may be found in.
>> ...
>> There is (most of the time) not actually a program called "sh". Various
>> different programs may provide a symlink "sh", pointing to their own shell:
> 
> Exactly.  And with many systems being personal these days, /bin/sh
> may point at a shell that is better for interactive use (like
> "bash"), while the user may prefer another (like "dash") scripted
> use that is not pointed by that single /bin/sh symbolic link.

I would argue 100% of interactive bash users, are running "bash" to get it. They are not running "sh" and then rewriting all scripts in /usr/bin from

#!/bin/sh

to

#!/usr/bin/dash

for the speedup.

The point is that if users set the "non-interactive scripts" command /bin/sh to GNU bash, they are fine with that being used everywhere (and it will in fact run all Git's scripts well).

Show 5 quoted lines

> In any case, we live in real world where things are not strictly
> POSIX.  Our Makefile does support with SHELL_PATH "sh", "dash", and
> "bash" just fine.  Why shouldn't I wish for feature parity in a new
> build framework that aims to at least compete and become an
> alternative?

But it's a very fair point that it's possible to need more than just POSIX. Meson can override program lookup:

$ cat paths.ini

[binaries] sh = '/usr/bin/bash'

$ meson setup builddirbash/ --native-file=paths.ini
[...]
  Runtime executable paths
    perl        : /usr/bin/perl
    python      : /usr/bin/python3
    shell       : /usr/bin/bash

A dedicated build option might be more discoverable, but it's certainly possible to override this today. Autodetecting the right one can be tricky...

-- 
Eli Schwartz