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Re: Incorrect alias expansion within command substitution

From: Alex fxmbsw7 Ratchev
Subject: Re: Incorrect alias expansion within command substitution
Date: Tue, 1 Feb 2022 19:22:33 +0100

On Tue, Feb 1, 2022, 19:16 Alex fxmbsw7 Ratchev <fxmbsw7@gmail.com> wrote:

> On Tue, Feb 1, 2022, 19:11 Chet Ramey <chet.ramey@case.edu> wrote:
>> On 2/1/22 10:23 AM, Chet Ramey wrote:
>> > If you defer alias expansion until execution, you lose the (posix-
>> > encouraged but officially unspecified according to the approved
>> > interpretation of issue 1342) ability to have aliases affect command
>> > parsing in the command substitution:
>> Well, I went back and read the entire interpretation. The part that's not
>> specified is whether an alias expansion provides the closing `)', but
>> alias
>> expansion has to be performed while parsing the contents of the command
>> substitution:
>> "existing aliases are required to be expanded when the shell parses the
>> input that follows the "$(" in order to find the terminating ')'"
> i see here only possible ) closing parsing, not doing so results in a mess

if, there is a closing loose ) in the alias, i assume its for usage there
non legit cases are the invalid coded ones ( the 'wouldnt work anyway cause
wrong know )

> for me, aliases as im bash ive experienced as text inplace replacements,
> flat text, then the cmdline parsing is done, so closing ) if easily
> specified by user yes works, else broken incomplete ( wrong pathed ) aliases
>> and (in the same interpretation):
>> "Historically some shells used simple parenthesis counting to find the
>> terminating ')' and therefore did not account for aliases. However, such
>> shells never conformed to POSIX, which has always required recursive
>> parsing (see XCU 2.3 item 5)."
>> So this seems like behavior that should be conditional on posix mode to
>> preserve backwards compatibility.
>> --
>> ``The lyf so short, the craft so long to lerne.'' - Chaucer
>>                  ``Ars longa, vita brevis'' - Hippocrates
>> Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/

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