bug#20796: [PATCH] Document behavior of sed -i -

[Jim Meyering]

On Mon, Jun 22, 2015 at 7:06 AM, Jim Meyering <address@hidden> wrote:
> On Mon, Jun 22, 2015 at 6:43 AM, Stanislav Brabec <address@hidden> wrote:
>> Jim Meyering wrote:
>>
>>> However, rather than documenting this surprising behavior,
>>> I propose to remove the anomaly altogether with the attached patch.
>>> Does anyone see a reason to retain the behavior of treating "-"
>>> like "./-"?
>>>
>> The reason is simple: "sed -i" makes no sense on stdin, so the special
>> handling od "-" is disabled.
>>
>> We can either ignore "-i" for stdin, or report error:
>> "Editing standard input in place is an undefined operation."
>
> Ignoring a fundamental user-specified option like -i is not an option,
> so I chose the latter: to make this nonsensical usage evoke
> a diagnostic:
>
>   $ sed -i s/a/b/ -
>   sed: couldn't edit -: is a terminal
>
> I chose to use the same diagnostic that was already printed for
> a case like "sed -i s/a/b/ /dev/stdin".  It feels slightly better to
> include the name of the offending device.

I've pushed that change.