The "-" and "--" options (was Re: ${var:1:1:=y})

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

On Feb 3, 10:44pm, Eric Cook wrote:
} Subject: Re: ${var:1:1:=y}
}
} On 02/03/2015 10:25 PM, Bart Schaefer wrote:
} >   All builtin commands other than precommand modifiers, even those that
} >   have no options, can be given the argument `--' to terminate option
} >   processing.  [...]  For historical reasons,
} >   most builtin commands also recognize a single `-' in a separate word
} printf , test/[, set -A and maybe a few others are exceptions to those
} rules.

Also "echo" does NOT accept "--" in this way, it ONLY acceps a solitary
"-".  I forget why that is.

printf : accepts -- but not -
test : accepts neither
set : the -A itself ends option processing, and "--" has added semantics