File Associations

File associations associate a file type with an application or applications. The type of a file is established by determining its MIME type. MIME types known by KDE are stored in $KDEDIR/share/mimelnk and each application's .desktop file contains a list of MIME types supported by that application.

kview.desktop:

MimeType=image/gif;image/x-xpm;image/x-xbm;image/jpeg;
image/x-bmp;image/png;image/x-ico;image/x-portable-bitmap;
image/x-portable-pixmap;image/x-portable-greymap;
image/tiff;image/jp2

kuickshow.desktop:

MimeType=image/gif;image/x-xpm;image/x-xbm;image/jpeg;
image/png;image/tiff;image/x-bmp;image/x-psd;image/x-eim;
image/x-portable-bitmap;image/x-portable-pixmap;
image/x-portable-greymap

Both can open image/gif Which one is used to open a .gif file?

The application with highest preference!. kview.desktop contains

InitialPreference=3

whereas kuickshow.desktop contains

InitialPreference=6

Therefore, KuickShow will be used to open .gif files.

How can we make KView default?

A user can change file association in the KDE Control Center. These changes are stored in $HOME/.kde/share/config/profilerc. To use the same settings for multiple users, store these settings in user profile directory or the global KDE config directory to use as default for multiple users.