/usr/share/xgreeters/unity-greeter.desktop is in unity-greeter 0.2.8-0ubuntu1.
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 | [Desktop Entry]
Name=Unity Greeter
Comment=Unity Greeter
Exec=unity-greeter
Type=Application
X-Ubuntu-Gettext-Domain=unity-greeter
|