How to allow non-root access to /dev/tty7

Question

I have problems running fbi without sudo. As user pi running

fbi -noverbose -nocomments -T 7 -1 -t 10  test.jpg
or
fbi -noverbose -nocomments -T 1 -1 -t 10 test.jpg

I get an error /dev/tty7: Permission denied.

tty1 and tty7 belong to group tty.

crw--w---- 1 root tty       4,  7 huhti 13 07:01 tty7

I have added user pi to groups tty and video.

sudo usermod -a -G tty pi
sudo usermod -a -G video pi

I added read permission crw-rw---- 1 root tty. Now theres no error but nothing is displayed. fb0 has also read and write permissions. — JPX, Commented Apr 13, 2018 at 7:03
"Now theres no error but nothing is displayed." Cross-check with sudo, do you get the same response with same command plus sudo, or not? — Fabian, Commented Apr 13, 2018 at 13:23
With sudo I get same information in console than without sudo but with sudo image is displayed. — JPX, Commented Apr 16, 2018 at 4:49
"With sudo I get same information in console than without sudo but with sudo image is displayed." Do you mean you get the image displayed and "Permission denied" if you run sudo fbi -noverbose -nocomments -T 7 -1 -t 10 test.jpg? — Fabian, Commented Apr 16, 2018 at 15:04

Seamus · Accepted Answer · 2018-04-14 19:48:57Z

1

This seems to be even more confusing in Raspbian than in *nix in general (and perhaps more confusing than it need be), but try this:

sudo raspi-config

go to 5 Interfacing Options

go to P6 Serial

select Yes

raspi-config responds:

The serial login shell is enabled

The serial interface is enabled

When asked if you want to reboot, answer Yes. Hope this helps; I can't test it on my RPi because it's headless.

answered Apr 14, 2018 at 19:48

Seamus

22.8k4 gold badges38 silver badges79 bronze badges

Thanks but that did not help. fbi behaves like without those settings.
– JPX
Commented Apr 16, 2018 at 4:50
So sorry... I'd try it on mine if it were connected to a monitor, but please follow up here when you solve it; the information will help someone else.
– Seamus
Commented Apr 16, 2018 at 12:25

Add a comment |

1 Answer 1