Re: Use of variables in the <x-y> globbing mechanism

["Nikolay Aleksandrovich Pavlov (ZyX)" <kp-pav@yandex.ru>]

21.04.2016, 10:18, "Bart Schaefer" <schaefer@brasslantern.com>:
> On Apr 20, 10:24pm, Henman wrote:
> }
> } It would be very useful if the <x-y> globbing mechanism would work with
> } variables.
>
> It can't do so because <$x-$y> is valid redirection syntax, meaning to
> read from file "$x-$y" and write to whatever comes after. It's rare
> enough to have files with digit-digit names that it was deemed OK to
> break the redirection rules in that special case, but it would cause
> to many problems to generalize it.
>
> } # The from_number and to_number are read in from a list of files to process
> } and injected between a filename pattern's prefix and extension.
> }
> } for file in ${SFNPAT:r}-<${from_number}-${to_number}>.${SFNPAT:e}
>
> Use the {x..y} syntax:
>
>     for file in ${SFNPAT:r}-{${from_number}..${to_number}}.${SFNPAT:e}
>
> This latter expands to the full list of names rather than globbing them,
> so it won't skip any missing files, but it will probably work in your
> example.
>
> If there may be gaps in the file sequence so you really do need to do
> the glob, put the entire expression in a variable like so:
>
>     local slice="<${from_number}-${to_number}>"
>     for file in ${SFNPAT:r}-${~slice}.${SFNPAT:e}

Variable can be avoided with the usual ${:-…} hack:

    for file in ${SFNPAT:r}-${~${:-<$from_number-$to_number>}}.${SFNPAT:e}