Cannot get gsettings set to work at boot using cron, rc.local, or autostart

Question

I am trying to "lock down" the computer by running a script at boot that turns lock on, lock screen after 10 min and require password, etc. I am using Ubuntu 12.04

I have tried editing crontab, anacrontab as well as rc.local to either run my script or actually inserted the code from the script into the files and I cannot get anything to work.

Any ideas?

* this is the only way I can get the commands to run in a script manually *

(su - $(logname) -c "gsettings set org.gnome.desktop.screensaver lock-enabled true")

(su - $(logname) -c "gsettings set org.gnome.desktop.screensaver lock-delay 600")

(su - $(logname) -c "gsettings set org.gnome.desktop.screensaver ubuntu-lock-on-suspend true")

(su - $(logname) -c "gsettings set org.gnome.desktop.screensaver user-switch-enabled false")

* These commands work if entered into terminal manually *

gsettings set org.gnome.desktop.screensaver lock-enabled true
gsettings set org.gnome.desktop.screensaver lock-delay 600
gsettings set org.gnome.desktop.screensaver ubuntu-lock-on-suspend true
gsettings set org.gnome.desktop.screensaver user-switch-enabled false

I also tried inserting the following code from other posts about using gsettings in cron with no luck:

DISPLAY=:0 
GSETTINGS_BACKEND=dconf
sessionfile=`find "${HOME}/.dbus/session-bus/" -type f`
export `grep "DBUS_SESSION_BUS_ADDRESS" "${sessionfile}" | sed '/^#/d'`

Also I double checked my script was executable and created /home/username/.config/autostart/screenlock.desktop:

[Desktop Entry]
Type=Application
Exec=/path/screenlock.sh
Terminal=False
Hidden=true
NoDisplay=true
X-GNOME-Autostart-enabled=true
Name[en_US]=screen lock
Name=screen lock

Also adding /path/screenlock.sh to bash.rc or .profile do not seem to work as well.

Answer 1

Instead of using:

DISPLAY=:0 
GSETTINGS_BACKEND=dconf
sessionfile=`find "${HOME}/.dbus/session-bus/" -type f`
export `grep "DBUS_SESSION_BUS_ADDRESS" "${sessionfile}" | sed '/^#/d'`

try to use:

PID=$(pgrep gnome-session)  # instead of 'gnome-session' it can be also used 'noutilus' or 'compiz' or the name of a process of a graphical program about that you are sure that is running after you log in the X session
export DBUS_SESSION_BUS_ADDRESS=$(grep -z DBUS_SESSION_BUS_ADDRESS /proc/$PID/environ|cut -d= -f2-)

See the explanation in my answer here.