Re: How to suppress/avoid *Async Shell Command* buffer?

[Marius Hofert <marius.hofert@math.ethz.ch>]

Barry Margolin writes:

> In article <mailman.41.1368897044.22516.help-gnu-emacs@gnu.org>,
>  Andreas Röhler <andreas.roehler@easy-emacs.de> wrote:
>
>> Am 18.05.2013 16:37, schrieb Marius Hofert:
>> > Hi Andreas,
>> >
>> > what do you mean by 'caused'?
>> >
>> > The question mark is a place holder for the file (foo.pdf).
>>
>> Okay, see dired-do-shell-command reads it
>>
>> > What does this have to do with *Async Shell Command* being opened?
>> >
>>
>> Nothing. It's the ampersand following ? which matters.
>>
>> > Note: The behavior of "!" on foo.pdf in dired mode is fine (in the sense
>> > that Okular opens, the pdf is shown, everything asynchronously), I just want
>> > to avoid the buffer *Async Shell Command* being opened.
>> >
>>
>> Which seems the buffer Emacs connects the process to.
>> Deleting it should end the processes, probably not a good idea.
>>
>> So the ampersand seems the culprit - not the question mark.
>> What happens when calling your stuff without it?
>
> This is essentially the same as using M-!, isn't it, except that it
> automatically fills in the filename argument? If you don't use the
> ampersand, Emacs waits for the command to finish, and then displays the
> output in *Shell Command Output*. If you use ampersand, it doesn't wait,
> and displays the output incrementally in *Async Shell Command*.
>
> Either way, the output has to be put somewhere.
>
> However, the synchronous mode has a feature: if the command produces
> little or no output, it doesn't switch to the *Shell Command Output*
> buffer, it just displays it in the minibuffer.  Here's a trick that I
> think should do what you want: Run the backgrounded command in a
> subshell (wrap it in parentheses):
>
> ! (command ? &>/dev/null &)

indeed, this also works, very nice!

Thanks, Barry.

Cheers,

Marius

>
>
> As far as Emacs is concerned, that's a synchronous command, because it
> doesn't end in "&". But it runs in the background within the subshell.
> Redirect the output so that Emacs immediately reads EOF, and has nothing
> to display in the minibuffer (it may display "(Shell command completed
> with no output)").