Re: grep-use-null-device

[David Kastrup]

Emilio Lopes <address@hidden> writes:

> Emilio Lopes writes:
>
>> As a result, if I forget to provide a filename to "M-x grep" it will
>> run forever, waiting for me to kill it.
>
> Richard M Stallman writes:
>
>>     So, my grep program supports "-H" but it apparently has not the
>>     expected semantics.
>
>> That is a very vague statement.  It tells us nothing.
>
> No, no.  It's very concrete if you consider the rest of the message,
> which you didn't quote.  Anyway, I understand the problem better now.
>
> If the user forgets to provide a filename to "M-x grep" (as in
> "grep.-nH.foo") it will run indefinitely waiting for input from
> stdin until killed.  In such cases it's useful to have `null-device'
> appended, even if the grep program supports the option "-H" (which
> has an other purpose anyway).
>
> One could even argue if Emacs should not append *two* instances of
> `null-device', in the case the use just press enter at the grep prompt
> without even typing a regexp.

I think what rather should be done is that standard input on the grep
process gets closed.  That requires no special options, and it will
lead to a sensible result without obscure extra options.

grep-use-null-device is just for getting file names on matches, not
for dealing with bad commands.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum