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Re: extglob patterns not expanded in -c command-strings


From: Chet Ramey
Subject: Re: extglob patterns not expanded in -c command-strings
Date: Sun, 27 May 2018 21:36:14 -0400
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:52.0) Gecko/20100101 Thunderbird/52.8.0

On 5/27/18 7:38 PM, address@hidden wrote:

> Bash Version: 4.4
> Patch Level: 19
> Release Status: release
> 
> Description:
> extglob patterns are not expanded in -c command-strings, even if extglob is 
> set within the command-string. For instance, running:
> 
> bash -c 'shopt -s extglob; echo @(foo*|bar*)'
> 
> generates this error:
> 
> bash: -c: line 0: syntax error near unexpected token `('
> bash: -c: line 0: `shopt -s extglob; echo @(foo*|bar*)'

Of course. This is how the shell should behave. Bash always reads at least
one complete line of input before parsing and executing any of the commands
on that line.

If you apply that rule, you can figure out the answer: extglob changes the
behavior of the parser, so it must be enabled before a command is parsed.
The complete line of input is read before any of it is parsed, and the
complete line is parsed before any of it is executed. As a consequence, the
extglob option must be enabled for the ( to be recognized as an extended
globbing pattern instead of an operator.

-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    address@hidden    http://tiswww.cwru.edu/~chet/



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