Use the build system

Build this article: a one-liner

$ nix-shell --run make

Further make targets

$ make rules.pdf
$ make <name>.pdf

Will make rules.pdf (resp. <name>.pdf)specifically

$ make rules
$ make <name>

Will run latexmk in continuous preview mode. From latexmk's man page:

The second previewing option is the powerful -pvc option (mnemonic: "preview continuously"). In this case, latexmk runs continuously, regularly monitoring all the source files to see if any have changed. Every time a change is detected, latexmk runs all the programs necessary to generate a new version of the document. A good previewer (like gv) will then automatically update its display. Thus the user can simply edit a file and, when the changes are written to disk, latexmk completely automates the cycle of updating the .dvi (and possibly the .ps and .pdf) file, and refreshing the previewer's display. It's not quite WYSIWYG, but usefully close.