I found eog to be too slow at rendering pictures for my purpose. I wanted to make feh (a commandline based image viewer) my default.

  1. Try and figure out how to change default.

    • right click image
    • properties
    • open with

    but I couldn't find feh listed as an option

  2. Edit feh's .desktop file

    • open /usr/share/applications/feh.desktop
    • change a bunch of stuff

    still cannot get feh to show up.

  3. Change the mime type default manually

    • edit ".local/share/applications/mimeapps.list" to map all image opens to feh.

      8,23c8,23
      < image/bmp=gpicview.desktop
      < image/gif=gpicview.desktop
      < image/jpeg=gpicview.desktop
      < image/jpg=gpicview.desktop
      < image/png=gpicview.desktop
      < image/tiff=gpicview.desktop
      < image/x-bmp=gpicview.desktop
      < image/x-pcx=gpicview.desktop
      < image/x-tga=gpicview.desktop
      < image/x-portable-pixmap=gpicview.desktop
      < image/x-portable-bitmap=gpicview.desktop
      < image/x-targa=gpicview.desktop
      < image/x-portable-greymap=gpicview.desktop
      < application/pcx=gpicview.desktop
      < image/svg+xml=gpicview.desktop
      < image/svg-xml=gpicview.desktop
      ---
      > image/bmp=feh.desktop
      > image/gif=feh.desktop
      > image/jpeg=feh.desktop
      > image/jpg=feh.desktop
      > image/png=feh.desktop
      > image/tiff=feh.desktop
      > image/x-bmp=feh.desktop
      > image/x-pcx=feh.desktop
      > image/x-tga=feh.desktop
      > image/x-portable-pixmap=feh.desktop
      > image/x-portable-bitmap=feh.desktop
      > image/x-targa=feh.desktop
      > image/x-portable-greymap=feh.desktop
      > application/pcx=feh.desktop
      > image/svg+xml=feh.desktop
      > image/svg-xml=feh.desktop
      
  4. Change the default feh command by copying /usr/share/applications/feh.desktop to ~/.local/share/applications

    11c11
    < Exec=feh
    ---
    > Exec=feh -Z %U