Re: bash read error

[Pascal]

yes. thank you.

Le mer. 1 juin 2022 à 16:25, Greg Wooledge <greg@wooledge.org> a écrit :

> On Wed, Jun 01, 2022 at 04:11:37PM +0200, Pascal wrote:
> > thank you Greg for these explanations and for these last three lines are
> > perfect for me.
> >
> > reading fails in the background process ("simply") because the keyboard
> is
> > monopolized (attached/reserved) by the foreground process ?
>
> That's... not an entirely incorrect statement, I suppose.  Not the way I
> think of it, though.
>
> From read(2) on Linux:
>
>        EIO    I/O error.  This will happen for example when the process
> is  in
>               a  background  process group, tries to read from its
> controlling
>               terminal, and either it is ignoring or blocking SIGTTIN  or
> its
>               process  group  is  orphaned. [...]
>
> Background jobs can't read from a terminal, because it would result in
> complete chaos.  Imagine you're running a nice, normal interactive
> foreground job, like a shell.  You try to type in the shell, which wants
> to read your input, but there's a background job that's running, which
> is also trying to read your input.  Who gets it?  Would half of your
> keystrokes go to your foreground shell, and half get sucked up by the
> background process?
>
> Nobody wants that, so the rule is "background processes can't read from
> the terminal".  There may be weird exceptions or something, I dunno, but
> that's enough for me.
>
>