Re: bash read error

[Pascal]

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 ?

Le mer. 1 juin 2022 à 14:04, Greg Wooledge <greg@wooledge.org> a écrit :

> On Wed, Jun 01, 2022 at 12:47:32PM +0200, Pascal wrote:
> > it's OK if I try this :
> >
> > wpa_supplicant -B -i wlan1 -c <(
> > cat <<~~~~
> > network={
> > ...
> > identity="test"
> > password=hash:0cb6948805f797bf2a82807973b89537
> > }
> > ~~~~
> > )
>
> So... the -c option of wpa_supplicant expects a filename?  OK.
>
> > but it's KO with bash: read: read error: 0: Input/output errors if I try
> to
> > read and convert informations before "cating" configuration :
> >
> > wpa_supplicant -B -i wlan1 -c <(
> > read -p 'user     ? ' user
> > read -p 'password ? ' -s passwd
> > cat <<~~~~
> > network={
> > ...
> > identity="${user}"
> > password=hash:$( echo -n "${passwd}" | iconv -t utf16le | openssl md4 |
> > egrep -o '.{32}$' )
> > }
> > ~~~~
> > )
> > user     ? bash: read: read error: 0: Input/output error
> > password ? bash: read: read error: 0: Input/output error
>
> Where is that 'read' supposed to be reading from?  The terminal?
> It's running as a background process, because it's inside a <() process
> substitution.  Background processes can't read from a terminal.
>
> > on the other hand, the use of a pipe is not a problem :
> >
> > (
> > read -p 'user     ? ' user
> > read -p 'password ? ' -s passwd
> > cat <<~~~~
>
> In this case, the 'read' commands are running in a foreground process.
> So they *can* read from a terminal.
>
> If you want the 'read' commands to work, and to use their values in
> a background process substitution, I would simply separate the two.
> Don't try to do them all in the same spot.
>
> read -r -p 'user: ' user
> read -r -s -p 'password: ' password
> wpa_supplicant .... -c <( stuff using $user and $password )
>
>