Create an Org file with a link to an existing PDF file. For example: [[file:~/circulant_diagonalization.pdf][file:~/circulant_diagonalization.pdf]]
(assuming the mentioned file exists at that path). In an attempt to open the PDF in the system viewer, position point over the link and type C-u C-u C-c C-o. The link opens in DocView, belying the docstring, which says: With a double prefix argument, try to open outside of Emacs, in the application the system uses for this file type. I reproduced with an empty Emacs init file. I use Ubuntu 16.04. The default PDF application is Okular. Emacs : GNU Emacs 25.0.93.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.18.9) of 2016-04-22 Package: Org-mode version 8.3.4 (8.3.4-39-ge0acd8-elpaplus @ /home/jorge/.emacs.d/elpa/org-plus-contrib-20160418/) current state: ============== (setq org-tab-first-hook '(org-hide-block-toggle-maybe org-babel-hide-result- toggle-maybe org-babel-header-arg-expand) org-speed-command-hook '(org-speed-command-default-hook org-babel-speed- command-hook) org-occur-hook '(org-first-headline-recenter) org-metaup-hook '(org-babel-load-in-session-maybe) org-confirm-shell-link-function 'yes-or-no-p org-after-todo-state-change-hook '(org-clock-out-if-current) org-src-mode-hook '(org-src-babel-configure-edit-buffer org-src-mode- configure-edit-buffer) org-agenda-before-write-hook '(org-agenda-add-entry-text) org-babel-pre-tangle-hook '(save-buffer) org-mode-hook '(#[nil "\300\301\302\303\304$\207" [org-add-hook change-major- mode-hook org-show-block-all append local] 5] #[nil "\300\301\302\303\304$\207" [org-add-hook change-major- mode-hook org-babel-show-result-all append local] 5] org-babel-result-hide-spec org-babel-hide-all-hashes org- eldoc-load) org-archive-hook '(org-attach-archive-delete-maybe) org-ctrl-c-ctrl-c-hook '(org-babel-hash-at-point org-babel-execute-safely- maybe) org-cycle-hook '(org-cycle-hide-archived-subtrees org-cycle-hide-drawers org- cycle-show-empty-lines org-optimize-window-after-visibility-change) org-confirm-elisp-link-function 'yes-or-no-p org-metadown-hook '(org-babel-pop-to-session-maybe) org-clock-out-hook '(org-clock-remove-empty-clock-drawer) ) -- - I am Brazilian. I hope my English is correct and I welcome corrections. - Please adopt free formats like PDF, ODF, LaTeX, Vorbis, Opus, WebM and 7z. - Free software for Android: https://f-droid.org/