/etc/xdg/autostart/alarm-clock-applet.desktop is in alarm-clock-applet 0.3.4-1build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 | [Desktop Entry]
Name=Alarm Clock
Comment=Wake up in the morning
Icon=alarm-clock
Exec=alarm-clock-applet --hidden
Terminal=false
Type=Application
Categories=GNOME;GTK;Utility;
X-Ubuntu-Gettext-Domain=alarm-clock
|