Re: [Help-bash] ${var//!([[:class:]])} removing characters of the [:class:]

[Mart Frauenlob]

On 27.01.2013 01:24, Clark WANG wrote:
> On Sat, Jan 26, 2013 at 3:13 PM, Mart Frauenlob
> <address@hidden <mailto:address@hidden>> wrote:
>
>     Hello,
>
>     am I wrong if I think that an extglob pattern of i.e. !([[:digit:]])
>     should match all non-digit characters? Why don't they match in the
>     example below? Why are non-digit chars removed?
>
>     # cat extg
>     #!/bin/bash
>
>     shopt -s extglob
>
>     echo "address@hidden"
>
>     x=".:3:."
>
>     echo "Y${x}"
>     echo remove digits
>     echo "Y${x//@([[:digit:]])}"
>     echo remove non-digits
>     echo "Y${x//!([[:digit:]])}"
>
>
> According to the bash manual, !(pattern-list) would match "anything
> except one of the given patterns". But the matching is string based
> rather than char based. So ${x//!([[:digit:]])} removed the string
> ".:3:." which does not match the pattern [[:digit:]].
>
> More example:
>
> $ shopt -s extglob
> $ v=foobar
> $ echo ${v//!(foo)/xxx}
> xxx
> $ echo ${v//!(bar)/xxx}
> xxx
> $

um, ok, thank you.

> But I don't know how to explain this result:
>
> $ echo ${v//!(foobar)/xxx}
> xxxxxx
> $

indeed strange.

x=abc
$ echo "${x/!([[:alpha:]])}"

$ echo "${x/[![:alpha:]]}"
abc

still why does the first example remove all alphabetic chars, there 
can't be a match???

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