Latexmkrc quickstart - you won't need more

.latexmkrc

# Setup directory with extra packages and documentclasses
ensure_path( 'TEXINPUTS', './extra//' );

# Setup out directory 
$out_dir = 'build';

# Setup main file
@default_files = ( 'main.tex' );

# Setup command options (use -shell-escape only if necessary)
set_tex_cmds( '-interaction=batchmode -shell-escape -halt-on-error %O %S' );

# Set LaTeX engine to use by default
$pdf_mode = 5; # use xelatex

# Setup extra extensions
push @generated_exts, 'run.xml', 'xdv';

# Use the default application of your linux desktop to preview pdfs 
$pdf_previewer = 'start xdg-open %O %S'