How do I change all fonts to sans-serif in Lilypond?

Question

I'm sure this information is available somewhere, but all I can find is how to change the font for specific parts, not the entire document. Can you help me?

Answer 1

Look here at the bottom: https://lilypond.org/doc/v2.24/Documentation/notation/fonts

So you need to do

\paper  {
  myStaffSize = #20
  #(define fonts
    (make-pango-font-tree "Sans Font"
                          "Sans Font"
                          "Typewriter Font"
                          (/ myStaffSize 20)))
}

to change the default serif font to sans. With 2.25 this gets a bit more user friendly: https://lilypond.org/doc/v2.25/Documentation/notation/changing-fonts

\paper  {
  property-defaults.fonts.serif = "Sans Font"
}

Note that this changes the default font to sans. If you want to have the choice to still use serif you can also (with 2.25) change the default family:

\paper {
  property-defaults.font-family = #'sans
}

\markup { Test \serif Test }

This might lead to use of serifs for certain markups where this is explicitely demanded, but since this is the default this should be uncommon I think.