Hello!
After some toying around I have gotten sage installed, and I have Texmaker installed. I have run the example.tex file that comes with sage through the pdflatex, which generated the .sage file. I then successfully compiled the .sage file within sage itself, and then recompiled in texmaker via pdflatex and got a fully configured file. Thus everything seems to be running fine.
I also adjusted the latexmkrc file as per http://www.highschoolmathandchess.com/pythonsage/integrating-sage-with-other-ides/
The problem comes when I try to configure the quickbuild to get Texmaker to run all of this at once. I have tried configuring the metapost to sage %.sagetex.sage and then created a macro to run latexmk then metapost then latexmk then pdfviewer as per this post here: http://tex.stackexchange.com/questions/251870/how-do-i-write-a-custom-command-to-enable-sage-in-texmaker/251872#251872
When I try to run that macro, it gives the oh-so-helpful error of "Error : could not start the command". For diagnostic purposes I tried running through the custom macro just latexmk, and just the custom metapost. Both work fine (minus the expected failures in context) individual, however the macro of latexmk then metapost gives that error.
The helpful people at the tex stackexchanged recommended I posted here to see if anyone had an idea as to where the error is and/or how to solve it.
