How can I run the slideshow in a specified order?

gwenview:

This is probably the best image viewer available at the moment. Built for KDE4, Gwenview comes with support for virtually all image formats out there, tools to do basic editing, tree-like file browser, support for tags, thumbnail previews, cropping, image rating system, slideshow, fullscreen mode, support for plugins and two view modes (Browse and View).

Let's install and use it:

sudo apt-get install gwenview

Now select your images and right-click on and choose Open With ► Gwenview

When the Gwenview GUI opens, select Sort By ► Date under the View menu

Now your added images are sorted by date, just go to the View menu and select Start Slideshow

Don't forget: before Start Slideshow you should select all added images in the Gwenview window to select to show in Slide show mode. cool!

Also here are a lot of Ubuntu Photo Slide Show applications.

I know this is an old question, but I just wrote a plug-in that allows sorting by date. It works with the GNOME Image Viewer (EOG) and I tested on the latest Ubuntu 21.10 and it works great. You can download the plugin here: https://github.com/cybereality/eog-modified-date-plugin