[SOLVED] can't chmod /boot/config.txt to add lcd_rotate

andyparker · 08-16-2022, 06:18 AM

New install of Debian 32 bit default distro on Pi 3b and need to rotate screen to suit 7"display. I can't make chmod take whatever su/sudo I use, eg if I

sudo chmod o+w config.txt -v

it reports mode changed from 0755 0757 but ls -l shows it has not changed and I can't save changes.

I realise I am probably setting myself to look a proper plonker but I have run out of ideas.

Turbocapitalist · 08-16-2022, 06:35 AM

What kind of a partition is it on? If it is on a legacy format like FAT or a derivative, permissions don't apply in the normal way.

Best then to access it through sudoedit or similar.

Code:

sudoedit /boot/config.txt

michaelk · 08-16-2022, 06:56 AM

Yes, the Pi's /boot partition is FAT32.

andyparker · 08-16-2022, 07:17 AM

Thanks chaps
sudoedit /boot/config.txt can't write file - permission denied

All the guides tell me to edit config.txt so it must be possible - I don't like how sudo chmod -v reported success incorrectly

teckk · 08-16-2022, 07:19 AM

Was the partition that config.txt is on mounted as root? Can't you write to that file as root? Can root create/delete files on that partition? Copy config.txt to somewhere, edit it, then rewrite the new config.txt.

On a FAT32 file system example:

Code:

sudo mount -t vfat /dev/sdb1 ~/mount/point

sudo touch ~/mount/point/config.txt

Root can write to config.txt. FAT32 doesn't support file permissions though.

andyparker · 08-16-2022, 11:14 AM

Sorry I don't know about partitions and mounts, it is just the default on a new Debian install on a raspberry pi3B.

After su -l I was able to copy a previously edited copy of config.txt back into /boot it doesn't however have the desired effect ie the screen is still upside down, I guess this a specifically pi issue.

I still don't like it telling me lies!

michaelk · 08-16-2022, 11:31 AM

If you can use su then you should be able to edit the file using either nano or vi. nano might be a little easier then vi.

su -
nano /boot/config.txt

andyparker · 08-16-2022, 03:25 PM

I can indeed edit config.txt as suggested but it still didn't change the screen orientation. There must be hundreds of posts giving this as the solution.
SOLVED - there is a utility in the gui under Preferences, Screen Configuration, Configure, Screens, DSI-1, Orientation where Inverted is an option.
Doesn't help if you don't want the gui mind.

boughtonp · 08-16-2022, 03:42 PM

Quote:

Originally Posted by andyparker

there is a utility in the gui under Preferences, Screen Configuration, Configure, Screens, DSI-1, Orientation where Inverted is an option.
Doesn't help if you don't want the gui mind.

If it survives a reboot then it needs to be saving that setting somewhere.

You can verify whether somewhere is config.txt by duplicating the file, toggling the setting, maybe rebooting, then checking if/how the file has changed.

Its failure to work may be because you're (possibly?) running stock Debian, and /boot/config.txt is a Raspbian-specific setting?
Please clarify exactly what version of Debian (and desktop) you're running. (inxi is a convenient tool for that.)

In any case, searching the relevant source repository for "orientation" or "inverted", and following what it does, may reveal where it's actually saved.

andyparker · 08-17-2022, 06:15 AM

The utility does not alter /boot/config.txt

inxi reports my distro as Raspbian GNU/Linux 11 (bullseye) and the Kernel 5.15.56-v7- armv7l
Desktop: LXDE 0.10.1

Searching the repository for those strings did not show anything useful to me at least.

boughtonp · 08-17-2022, 07:25 AM

LXDE has lxrandr, which is a GUI for xrandr.

Since it's a wrapper, that explains why it might not contain orientation/inverted itself, but its code does have a save_configuration function, the relevant part of which is:

Code:

    file = g_build_filename(  g_get_user_config_dir(), 
                              "autostart", 
                              "lxrandr-autostart.desktop", 
                              NULL );

g_get_user_config_dir is a GTK function that returns the value of XDG_CONFIG_HOME which defaults to "~/.config"

In other words, lxrandr probably saves to "/home/$USER/.config/autostart/lxrandr-autostart.desktop"

If so, that change will only come into effect after login - it you have a login screen which is correctly oriented then it would need to be something not user-specific, possibly in "/etc/xdg"

andyparker · 08-17-2022, 09:24 AM

Thank you boughtonp, my autostart directory only contains a file LXinput-setup.desktop which I think was written when I used LXinput and a Coordinate Transformation Matrix to get the touchscreen in sync with the display - always handy!
I am content that what I have works correctly now even if the method is probably not the best or most efficient.

If continuing this discussion might prove useful to others I am happy and interested to proceed, my problem being that a lot has changed since my SVr4 course in 198?

The login screen is correctly oriented but everything prior to that is inverted.

No recent files in /etc/xdg apart from some in lxpanel from intallation 2 days ago.

boughtonp · 08-17-2022, 09:38 AM

If the login screen is the first point it's correct then my understanding is that the display manager is where it would be handled - for LXDE that would be LXDM, and man lxdm lists relevant files as being in "/etc/lxdm/"