Overview
The standard PDF viewer included with the GNOME environment in Oracle Linux 7 is Document Viewer from Evince. While it is a decent PDF viewing utility, it is missing some features. I have found another PDF utility for Oracle Linux that provides some cool features.
Background
When we show Oracle Linux on a laptop (Server with GUI) at conferences and events, we want to display slides about Oracle Linux as an "attention-grabber". While Microsoft PowerPoint can easily do looping presentations, PowerPoint is not available on Linux. The default PDF viewer included in the Oracle Linux 7 GNOME environment (Document Viewer) is missing two desired key features: (1) no way to auto advance slides, and (2) no way to set the presentation to loop over and over until manually interrupted.
Adobe Acrobat Viewer was a viable alternative as it did have a looping feature, but Adobe has discontinued development of Acrobat for Linux. The last release is quite old (circa 2013), requires 32-bit dependencies and is no longer available on any Adobe Yum repositories. It is not available on EPEL, either. I decided that Adobe Acrobat Reader for Linux was too risky and too much trouble.
In preparation for our recent Oracle Open World event, I did some more research and discovered a great PDF viewer for Linux... Okular
Even though Okular is part of the KDE environment, I found that it works great under GNOME. And it is easy to install and configure.
Installation, Configuration, and Use
Okular is included in the Oracle Linux 7 Latest channel, and it does not have any dependencies to any other channel. It is very easy to install. Simply run the following command (as root):
# yum install okular
The icon for Okular will be in Applications - Graphics
To configure Okular to advance slides automatically after a delay, and to set up looping mode - go to Settings - Configure Okular
Click the Advance every: check box and set the slide display time. To loop until interrupted, click the Loop after last page check box. Don't forget to click Apply, then OK:
To begin a looping presentation, File - Open in Okular then View - Presentation (keyboard shortcut for Presentation mode is Ctrl+Shift+P)
To change the default association in GNOME from Document Viewer to Okular, in the Files app Right Click on a PDF file, then click Properties
Click the Open With menu, then click Okular, then click Set as default
This will set Okular as the default PDF viewer for all PDF files for this specific Oracle Linux user.
I hope you find Okular to be a helpful PDF viewer for Oracle Linux!