Forcing tikz externalization to recreate all images using arara

Question

I am using the externalization library of tikz to have most of the pictures compiled only once and just included in later LaTeX runs.

Once in a while I would like to redo all the images, for example after making changes to the font. To achieve this I used to manually delete the externalized files, OR adding the line \tikzset{external/force remake} somewhere before my first picture and commenting it for the future runs.

Since I just discovered arara I would love to have myself some automation ;)

How do I achieve with arara to either

• delete the content of an entire folder, not knowing how many files are in there or what they're called or
• add a line of code in the .tex file for one single run, in this case: \tikzset{external/force remake}

Sorry, but I don't have a single clue on how to start with rules or directives. But this snippet could serve as a starting point

% arara: cleanfolder: { folder: tikzternalize }
% !arara: insertforceremake
% arara: pdflatex: { shell: yes }
\usepgfplotslibrary{external}
\tikzsetexternalprefix{tikzternalize/}

Answer 1

After some copy/pasting from existing rules and research I came up with a working solution, although I am not entirely happy with it...

Instead of removing all the files from an exisiting folder, I simply delete the directory and recreate it in the same place. Empty, of course.

!config
# Rule for deleting the contents of a folder with arara
identifier: cleanfolder
name: CleaningTool for a whole folder
commands:
 - <arara> @{ isWindows( "cmd /c rmdir /s/q", "rm -f" ).concat(' "').concat(folder).concat('"') }
 - <arara> @{ isWindows( "cmd /c md", "mkdir").concat(' "').concat(folder).concat('"') }
arguments:
 - identifier: folder
   flag: <arara> @{parameters.folder}

I would be very happy with any comment on this, for I think the problem could be solved a lot more "elegantly" than with what I produced.

Update:

I even managed to address the second part of my question myself. Inspired by Chris' answer to Using arara to compile powerdot twice I modified the pdflatex rule that is shipped with arara to define some sort of switch command that triggers the desired action in the .tex file if the switch is correctly defined.

rule: pdflatexwithswitch

!config
identifier: pdflatexwithswitch
name: run PDFLaTeX with specified switch and optional value
command: <arara> pdflatex @{action} @{draft} @{shell} @{synctex} @{options} "\def\@{switchname}{@{switchvalue}}\input{@{file}}"
arguments:
- identifier: action
  flag: <arara> --interaction=@{parameters.action}
- identifier: shell
  flag: <arara> @{isTrue(parameters.shell,"--shell-escape","--no-shell-escape")}
- identifier: synctex
  flag: <arara> @{isTrue(parameters.synctex,"--synctex=1","--synctex=0")}
- identifier: draft
  flag: <arara> @{isTrue(parameters.draft,"--draftmode")}
- identifier: options
  flag: <arara> @{parameters.options}
- identifier: switchname
  flag: <arara> @{parameters.switchname}
- identifier: switchvalue
  flag: <arara> @{parameters.switchvalue}
  default: 0

The rule in action:

demo.tex

% arara: pdflatexwithswitch: { shell: yes, switchname: forceremake, switchvalue: doit }
\usepgfplotslibrary{external}
\ifthenelse{\isundefined{\forceremake}}{}{\ifthenelse{\equal{\forceremake}{doit}}{\tikzset{external/force remake}}{}}

I am much more content with this one. Comments still welcome.