Let auctex run pdflatex command on the tex source when it has been changed.

[Hongyi Zhao]

On Ubuntu 20.04, I'm using git master version of Emacs and auctex. At
the same time, I use the following configurations to do the forward
and inverse search:


;https://www.emacswiki.org/emacs/AUCTeX#h5o-24
;https://www.emacswiki.org/emacs/AUCTeX#h5o-27
;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; ;;;;;;;;;;;;;;;;        LaTeX         ;;;;;;;;;;;;;;;;;
;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; ##### Don't forget to configure
;; ##### Okular to use emacs in
;; ##### "Configuration/Configure Okular/Editor"
;; ##### => Editor => Emacsclient. (you should see
;; ##### emacsclient -a emacs --no-wait +%l %f
;; ##### in the field "Command".

;; ##### Always ask for the master file
;; ##### when creating a new TeX file.
(setq-default TeX-master nil)

;; ##### Enable synctex correlation.
;; ##### From Okular just press `Shift + Left click' to go to the good line.
;; ##### From Evince just press `Ctrl + Left click' to go to the good line.
(setq TeX-source-correlate-mode t
      TeX-source-correlate-start-server t)

;; ### Set Okular as the default PDF viewer.
(eval-after-load "tex"
  ;'(setcar (cdr (assoc 'output-pdf TeX-view-program-selection)) "Okular")
  '(setcar (cdr (assoc 'output-pdf TeX-view-program-selection)) "Evince")
  )

But I want to know how to automatically trigger auctex compilation on
the tex source file with pdflatex every time I've changed and saved
the Tex source file.

Regards
-- 
Assoc. Prof. Hongyi Zhao <hongyi.zhao@gmail.com>
Theory and Simulation of Materials
Hebei Vocational University of Technology and Engineering
NO. 552 North Gangtie Road, Xingtai, China