[Live-demo] changing the login screen backdrop on ubuntu 10.04 and 12.04

[Angelos Tzotsos]

On 07/29/2012 10:54 AM, Hamish wrote:
> Hi,
>
> I don't think I've posted these notes yet & I'm not sure if they'll be
> needed or not.
>
> with 12.04 xubuntu has switch to lightdm instead of gdm for its login screen.
> actually gdm takes a bit less memory to run at the current versions, but is
> just fresh from a rewrite so maybe similarly buggy to the newly written
> lightdm.
>
> in the past we'd manually set gdm's auto-login config, and fortunately
> lightdm is controlled by text files in /etc/lightdm/ not gnome's gconf
> editor, so it's pretty simple to do, see /etc/lightdm/lightdm.conf.
>
> one question that came up in the past is what if we wanted to change the
> backdrop on that login screen to have some text saying what the pswd was
> etc. with the current setup you only see that screen if you log out, which
> you might do to change the language. If you didn't read the notes you
> wouldn't otherwise know what the pre-set pswd was.  /shrug
>
> anyway, if you ever want to do it, here it is. As a bonus for archive
> searchers I'll throw in how to do it on Lucid too, and how to set up dual
> monitors with lightdm's login screen on xubuntu 12.04.
>
>
> ubuntu 10.04 lucid:
>
> # set the image
> sudo -u gdm gconftool-2 --set --type string \
>     --set /desktop/gnome/background/picture_filename \
>           /usr/local/share/images/your_new_background.jpg
>
> (default is /usr/share/backgrounds/warty-final-ubuntu.png)
>
> # also, you might want to scale it differently:
> sudo -u gdm gconftool-2 --set --type string \
>           --set /desktop/gnome/background/picture_options scaled
>
> #scaling options are none, wallpaper (tiled), centered, scaled,
> #  stretched, zoom, and spanned (across 2 monitors)
>
>
> # if not stretching to full screen, do this to avoid purple borders:
> sudo -u gdm gconftool-2 --set --type string \
>       --set /desktop/gnome/background/primary_color "#000000"
>
>
> ----------------------------
>
> ubuntu 12.04 precise:
>
> lightdm background image is pretty easy:
>    edit /etc/xdg/lubuntu/lightdm/lightdm-gtk-greeter.conf
>
>
> To change the background image in GDM (regular ubuntu not xubuntu)
>
> from  http://smashingweb.ge6.org/change-the-background-of-gnome-3-gdm-login-screen/
>
> quoted:
>
> """
> # su - gdm -s /bin/bash
> $ dbus-launch
>
> The above command will print DBUS_SESSION_BUS_ADDRESS and DBUS_SESSION_BUS_PID. We need to export them
>
> $ export DBUS_SESSION_BUS_ADDRESS=unix:abstract=/tmp/dbus-Jb433gMQHS,guid=fc14d4bf3d000e38276a5a2200000d38
> $ export DBUS_SESSION_BUS_PID=4283
>
> Check to see if dconf-service is running and if not, start it like this
>
> $ /usr/lib/dconf/dconf-service &
>
> Set the wallpaper
>
> $ GSETTINGS_BACKEND=dconf gsettings get org.gnome.desktop.background picture-uri
> $ GSETTINGS_BACKEND=dconf gsettings set org.gnome.desktop.background picture-uri "file:///usr/share/backgrounds/gnome/SundownDunes.jpg"
>
> You will need to point to a file where the gdm user has permission to read, not in your home directory.
> """
>
> then as root restart the gdm service.
>
> for precise I had to "chown gdm.gdm /var/lib/gdm/.config -R" first, as root owned that not the gdm user, so the gdm user couldn't write the file.
> seems like an oversight.
>
>
> -------
>
> finally, dual monitor setup for the login screen:
>
> [if you installed the nVidia proprietary driver you can save an X.org
> config file with that already set up, otherwise do this]
>
>   (gdm on ubuntu 12.04)
> - run arandr and make a setup script
> - move it to /usr/local/bin/dual-monitors.sh
> - edit /etc/gdm/Init/Default
>
> add "/usr/local/bin/dual-monitors.sh" before gdmwhich()
>
>
> lightdm on ubuntu 12.04:
> - same as above, add script to
>
> cat << EOF >> /etc/lightdm/lightdm.conf
>
> [SeatDefaults]
> greeter-session=lightdm-gtk-greeter
> user-session=xubuntu
> display-setup-script=/usr/local/bin/dual-monitors.sh
> EOF
>
>
>
> maybe it helps sometime,
> Hamish
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>
Thanks Hamish, this is really helpful.
Should we go on and change the login image?

Angelos

-- 
Angelos Tzotsos
Remote Sensing Laboratory
National Technical University of Athens
http://users.ntua.gr/tzotsos