Re: incorrect brace expansion when using default values

[Chet Ramey]

Chris F.A. Johnson wrote:

>    Quote them, and they do expand:
> 
> $ foo() { echo "${1:-"a{b,c}"}" ; }
> $ foo
> ab ac

Brace expansion is essentially separate from the rest of the expansions:
in fact, it's designed to be part of a separate library if desired.  As
such, it doesn't implement all of the shell's somewhat quirky quoting
semantics.  It understands simple single- and double-quoted strings and
backslash escapes.  The manual is perhaps not as clear about this as it
could be.

The quoted string, once the brace expansion code finishes, comes out like
this:

"${1:-a"b"}" "${1:-a"c"}"

>From there, the results observed should be understandable.

Chet

-- 
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Chet Ramey, ITS, CWRU    chet@case.edu    http://cnswww.cns.cwru.edu/~chet/