/usr/share/mimelnk/application/x-qgis-project.desktop is in qgis 2.8.6+dfsg-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]
Type=MimeType
MimeType=application/x-qgis-project
Hidden=false
Comment=QGIS Project
Comment[de]=QGIS-Projekt
Patterns=*.qgs;
Icon=qgis-mime
X-KDE-IsAlso=application/x-qgis
|