From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ot1-f53.google.com (mail-ot1-f53.google.com [209.85.210.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8B383134A0 for ; Fri, 29 Dec 2023 19:36:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=networkplumber.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=networkplumber.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=networkplumber-org.20230601.gappssmtp.com header.i=@networkplumber-org.20230601.gappssmtp.com header.b="Y31anWSQ" Received: by mail-ot1-f53.google.com with SMTP id 46e09a7af769-6dbca115636so4271753a34.2 for ; Fri, 29 Dec 2023 11:36:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20230601.gappssmtp.com; s=20230601; t=1703878594; x=1704483394; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=rOa0KZTkFN6UH7WU72Y2lMkvi0VinggiqwwLcCgErS0=; b=Y31anWSQl/d9IaG28QZKe0gKQll2ekpQlz36mBUiVR8j0lXE4HfK1+CUNum79MtWnX KGYFHid5lRtJimXnbJ25pjsDGm061/d8hE9UpzbLHpuToSyBIsjeYaNnGsde7JTf9Dyz AzdJb1dHvW+/nr/qyGdt7ffk/CXNwPF/N5yywKRfvYf5778kO4kQQuRsPhmb5F2fgEnZ jaTNol2sgR+OdOUIaXE2aiydTuvsIEe6nr3AmA8R7uynpzp9gkFZDp6tyUeXm39DhhJT ABwCO4qqupR/KDBmB5G9NRFrzTRg1+KvVDtqBja6oq9uVADlF0sMlRBUQ7sQYMumH5bg A+oA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703878594; x=1704483394; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=rOa0KZTkFN6UH7WU72Y2lMkvi0VinggiqwwLcCgErS0=; b=cPAuaqjcwHgIZfAdfrscZaQH4TWSsADFetcIpMkMmNGeoMbwFSNbhfhMbSS0E24CeA tXU5c4j3f8uyE7vA4EsoZyiLvk6/hc+yrYA7E9JR9vifOJEfXqKyafR5H7fHyvGNXppU nEVi88rNUlSWmXsvksdg37m37QUMieGtN1VE7idzF4rlH3XbWDYxWtzv4TnkcLBf0nBI 3ieympD0eszlZhFOs+8SZEgK90wtELm7VzDdNZs+cc+zF+pG9xQzGHkKXajq0pddMOo4 Zr1WRGggaZxRusQFMzZ/OiYGxVv04cmYPKNvbOB6fMJ6XChTJRbYn8hl7RK3Rz5B8gK0 UWbQ== X-Gm-Message-State: AOJu0Yyamv7E60+KGphc1t292v7Ui3W7b6xfRxqdP9GHfCO8Hev5cJzQ Cd1XcVrGf5XV3MsIcWxNmJO8wLOGRNq8ybI0Vx9co3vs4FE= X-Google-Smtp-Source: AGHT+IFBJhHQnmbIeZs1XdMOHwRoYn0Cb43AFoElHIP0/WdhzHGJcX8cQyNivuCpzKiN58LmNJwUuA== X-Received: by 2002:a9d:74c4:0:b0:6dc:2a0:26a2 with SMTP id a4-20020a9d74c4000000b006dc02a026a2mr4384073otl.56.1703878594470; Fri, 29 Dec 2023 11:36:34 -0800 (PST) Received: from hermes.local (204-195-123-141.wavecable.com. [204.195.123.141]) by smtp.gmail.com with ESMTPSA id p184-20020a625bc1000000b006d8610fcb63sm16252783pfb.87.2023.12.29.11.36.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 29 Dec 2023 11:36:34 -0800 (PST) Date: Fri, 29 Dec 2023 11:36:32 -0800 From: Stephen Hemminger To: Eli Schwartz , David Ahern Cc: netdev@vger.kernel.org Subject: Re: [PATCH iproute2 1/2] configure: avoid un-recommended command substitution form Message-ID: <20231229113632.45c70893@hermes.local> In-Reply-To: References: <20231218033056.629260-1-eschwartz93@gmail.com> <20231227164610.7cbc38fe@hermes.local> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Wed, 27 Dec 2023 22:57:10 -0500 Eli Schwartz wrote: > On 12/27/23 7:46 PM, Stephen Hemminger wrote: > > On Sun, 17 Dec 2023 22:30:52 -0500 > > Eli Schwartz wrote: > > > >> The use of backticks to surround commands instead of "$(cmd)" is a > >> legacy of the oldest pre-POSIX shells. It is confusing, unreliable, and > >> hard to read. Its use is not recommended in new programs. > >> > >> See: http://mywiki.wooledge.org/BashFAQ/082 > >> --- > > > > This is needless churn, it works now, and bash is never going > > to drop the syntax. > > > Per the patch message, the reason to avoid the syntax is because it is > confusing, unreliable, and hard to read. > > It was deprecated for good reason, and those reasons are relevant to > people writing shell scripts! Regardless of whether it is removed, it > has several very sharp edges and the modern alternative was designed > specifically because the legacy syntax is bad to use *even in bash*. > > (bash has nothing to do with it. But also, again, this is not about bash > because the configure script shebang is *not* /bin/bash.) The existing configuration was built incrementally over time. Mostly as a reaction to the issues with autoconf. Perhaps it is time to consider updating iproute2 to a modern build environment like meson that has better config support.