This article originally appeared on http://olezfdtd.wordpress.com I’ve copied it over to my current blog to consolidate all my blogging efforts over the years in one place.
KDE (and linux) in general has a very elaborate system of guessing the file type of your file, that depends on both the file extension and the file contents. In 99% of the cases these rules work, unfortunately the other 1% has been annoying me for quite some time.
If you create a matlab m-file that starts with comments (% some comment), KDE will think the file is a latex file and insist on opening it with a dedicated latex editor. This behaviour can be changed by modifying the mime type definitions.
/usr/share/mime/packages/freedesktop.org.xml in your favourite text editor as root.
Find the node
<mime-type type="text/x-tex">. This will have a subnode that looks like:
<magic priority="10"> <match value="%" type="string" offset="0"/> </magic>
Change the priority to something smaller than 10, so it has a lower priority than the matlab magic rule. Now run
sudo update-mime-database /usr/share/mime
And that’s it. KDE will now see all your m-files as matlab scripts even if they start with a comment.