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[108.200.163.197]) by smtp.gmail.com with ESMTPSA id w5-20020a9d70c5000000b006d7eaaa65a4sm2445449otj.71.2023.12.27.19.57.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 27 Dec 2023 19:57:11 -0800 (PST) Message-ID: Date: Wed, 27 Dec 2023 22:57:10 -0500 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH iproute2 1/2] configure: avoid un-recommended command substitution form Content-Language: en-US To: Stephen Hemminger Cc: netdev@vger.kernel.org References: <20231218033056.629260-1-eschwartz93@gmail.com> <20231227164610.7cbc38fe@hermes.local> From: Eli Schwartz Autocrypt: addr=eschwartz93@gmail.com; keydata= xsFNBFcpfj0BEADkTcFAwHJmtXbR7WHu6qJ3c83ccZl4qjBsU//JEn9yTtfj8M2a3g+lpGAF C/8isGz9InmrqBn1BXQFwcySAkRYuromR5ZPH1HIsv21RTtJbo5wCs8GlvoRYsp5pE7JEIVC RsWixG5pFhinlssUxtm0szlrzfaKanohWDfj+2WuWh4doXJZtTQePCGpouSziButkwkgQMqE U+ubBiTtjF/f/oCyC6YMWx+5knaqNSWxjF52rXAngVD0YYAiJ7o0KOQhrC2RLF+l0x4hRikp QaZrqVL1CaP7gjceOlOZ/zdCOImAaha9ygZiJG652HCIPfsy7uypYwxoMEeldoTnsXbjJXuL fMwIp8dCVbKMhebXdCNIWCjNewusz3I4+JjOO+uPgA+YgHu8+A56tpJ7lmHw5C95XjheXt/N bo9HONG4oeILZ9pQxnx93ocZM6v0W+taoBbPzOLE0al7Oy5vmJwO/QkprDU/TkzPtrgiCKPV Ml/+smp5FXbOjp/Y5UVlFmj2aemDIVAv70RlewAytwQLdGHLv3Au81hq5xrX7JAopEkfhYJY g2+7s78C0VaMPXHw2XyLpj5uPBR2q8KihSaASfhGBH0IcxLd+lEq1+NHT2l/WlQVjRfXHZns k8giW8M12TJZvvm9rpXMAFk7zSmmojp1M/7+ImOTcDYvErW1iQARAQABzSRFbGkgU2Nod2Fy dHogPGVzY2h3YXJ0ejkzQGdtYWlsLmNvbT7CwZQEEwEKAD4CGwMFCwkIBwMFFQoJCAsFFgID AQACHgECF4AWIQS9J7B6XvRcKtr3DgSEgYpoGa9KmwUCYstIWwUJEUVkngAKCRCEgYpoGa9K m50AEACoEoXaBaVerjTGbezOHK8J+GWkDJQ8wetJJfHhBgDq/lypKF+1LmolXAkmJF29ShBx r9zr5n91E1xn4bX53X8NdVAf2r/dFMtzlu0jsl0UcZ6OllpkTBtWqbjNgAI+C/v/lbBVcCz+ irtrRfM/guLNaaUuZlh+Qtt4kdKygP64jhqRude/eD0tAVzXbnka0k2E40dNT8W23SPnbjJh gpZeGeufIf8xFddDdLaqZMuxjDcxqq1jcasPB8M57Vkt5NpTaIvCtO4ZWejoj9im+Onsdvfs 3mCHr1DcIEAYj36/2U8yXzpsdgFXD96WcLFRL3l4ELTAPua3MFNdty6Bf35Yli1Fby4yOnf8 5UQd4SRh1pYqBoBw7uEtY8qOJR+bvqo2XnTrR9HVYBZVrVhFe/CCSxOfm2ZxZn2bzMzoJZ5X jcMNGdkHVcutvgJOIUASnwSoJM4hoVdwRmGgrT1Mu18rkk05+NjElPmGcn9vFZXVddnqvuqd gf4di2xl0adpWgFFSfKeOBjNcPSQqNLjNcJTGVJ0lvlmGcYfyw020IoGu/bBEUpQA12i/4JE N5Qx1frWsvXQ+ioJkFsjydbpWqLR5xI44p1FWU2lwKT4QbtSkgx9sHOec+DIIarwxqDiMXR9 ZhG/Ue7+pXAVD/Zs/XtxXCZQBhl7keIXTmZKTccuYM7BTQRXKX49ARAAo1bWz1d7RvffuaX9 SAOqQEfeEHaRilIKpqU5+yuBSd7vLNF1QPb105cuMJtj0bHhQnqYlToNODAHn9Ug+Axgz3dT +s8j1/mizFLfgpHnWdNr7/a1lMPhmPqtoeEdUAd0bqX94xHedZBtlvhLAwoelNhatJkqbrWc voI9d3RMLA3tPrTxY6aeDTa+5LL8oHeZ04KXlWxQIqxXT+e0JEs+0V9viicYy/8i4DqfObtr jdNOV3cKCW3rmNTATlVmciGY8xHkwM77C67ibFyYOdoYo6IP7EUI1oTBZN1M2A23sSgUlAHP qPFwD38JPiBLYu5pIA3SwDaatTD/+BEdhsiIQsZaWsn0E98Bb0bHfukMvEYFEcwA//HXTVIN SGry/Tc9baIgD0hG8ImDCbR9RfXdz0uzelHypcKGnGB7FLtZ8Vw4swa06CXEGG0Oo5AfYRuU 2bQtFxH66xHEFSfgfpTy5nHTH9Ra1mTtpoDil6rMLq1q43w5XP7oEucZwdZa+hlj2M4I/i+I gcaU+Bd9bQMa2mmvmI7pOFMxCCvprY5fDaRY1v8rKWRg12bD4kYM3npR37rWkk+Zdj+w+XgS oCW0gNT2yHDDMq7H6qYUjyvaG8l0vhWb44rzQLBFfQv/Lc3QI4jUu6e7TbQui3cw5Qn0E+yu 4teV2fIVDbLB8wvRS/8AEQEAAcLBfAQYAQoAJgIbDBYhBL0nsHpe9Fwq2vcOBISBimgZr0qb BQJiy0j1BQkRRWU4AAoJEISBimgZr0qbjUwQAL+qByV+VpVmD3Guqym9uUX/gUmLdLar7ZrM Nr3RnDo/N0Dl2IZpm+eoNGlnBh2+q6bcZUWWoEtbOoy6XrlPnx3Cf+Bg4bFDNN4ibIQkYV2z cU9E1AWadCKUm1Z2eDqjc5TlLZiyUGQUh4kAW2Z3gFe1ffhyKarVExfTSxwE1ec5Q9cy6T29 iO3QjAD3v7R9EXZJIn/RRbsaWQSQLz+DVDZxjy2XcmTGLS3HMIqdYFHYAxUx7HLbCAhfIyD0 TDsMOutl3B2PWENYWmhO6E+USSwPokx461ePqcYG5haqnoUcXGQ2SGtLaoQ2iKGvGAe17xpQ yHK7NGSPWOEmYSJ1bRFJYKoe8+jtesoEY335hyQRn7RbMvTslVUvtVjRYu4FXOwPXT3NLbj8 v+in+Njm1UfuWvOZS695wepBGvDtMM3Ze+ZRB3S7zmo1/eKol1cQQ/abYlX+7TrUbxcQ+bAQ b8PeDaL4sAH77fE6m+3jsMb1CFbN3+LcaUxGV7ysh7kVYVqwhiRqnmF0E3I9z3nyZ9HQgwHt 1jmoa4lMiRDnkkOFdhoJ3vqmxHKW9XtxrUJlLQfTejUSooLFjNe6tvXgrTvrosGTpDZIIT0/ 8qKt4Nxg06u0jmnXMbbWwoPNWl9PfcPtNhjaycocCzfog5LI8N7HbRy+jHmArWAywaZVLrLe In-Reply-To: <20231227164610.7cbc38fe@hermes.local> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit 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.) -- Eli Schwartz