/usr/share/lilypond/2.18.2/ly/ is in lilypond-data 2.18.2-12build1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/lilypond/2.18.2/ly/Welcome-to-LilyPond-MacOS.ly
/usr/share/lilypond/2.18.2/ly/Welcome_to_LilyPond.ly
/usr/share/lilypond/2.18.2/ly/arabic.ly
/usr/share/lilypond/2.18.2/ly/articulate.ly
/usr/share/lilypond/2.18.2/ly/bagpipe.ly
/usr/share/lilypond/2.18.2/ly/catalan.ly
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/usr/share/lilypond/2.18.2/ly/deutsch.ly
/usr/share/lilypond/2.18.2/ly/drumpitch-init.ly
/usr/share/lilypond/2.18.2/ly/dynamic-scripts-init.ly
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/usr/share/lilypond/2.18.2/ly/engraver-init.ly
/usr/share/lilypond/2.18.2/ly/espanol.ly
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/usr/share/lilypond/2.18.2/ly/festival.ly
/usr/share/lilypond/2.18.2/ly/generate-documentation.ly
/usr/share/lilypond/2.18.2/ly/generate-interface-doc-init.ly
/usr/share/lilypond/2.18.2/ly/grace-init.ly
/usr/share/lilypond/2.18.2/ly/graphviz-init.ly
/usr/share/lilypond/2.18.2/ly/gregorian.ly
/usr/share/lilypond/2.18.2/ly/guile-debugger.ly
/usr/share/lilypond/2.18.2/ly/init.ly
/usr/share/lilypond/2.18.2/ly/italiano.ly
/usr/share/lilypond/2.18.2/ly/lilypond-book-preamble.ly
/usr/share/lilypond/2.18.2/ly/makam.ly
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/usr/share/lilypond/2.18.2/ly/norsk.ly
/usr/share/lilypond/2.18.2/ly/paper-defaults-init.ly
/usr/share/lilypond/2.18.2/ly/performer-init.ly
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/usr/share/lilypond/2.18.2/ly/predefined-fretboards-init.ly
/usr/share/lilypond/2.18.2/ly/predefined-guitar-fretboards.ly
/usr/share/lilypond/2.18.2/ly/predefined-guitar-ninth-fretboards.ly
/usr/share/lilypond/2.18.2/ly/predefined-mandolin-fretboards.ly
/usr/share/lilypond/2.18.2/ly/predefined-ukulele-fretboards.ly
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/usr/share/lilypond/2.18.2/ly/script-init.ly
/usr/share/lilypond/2.18.2/ly/spanners-init.ly
/usr/share/lilypond/2.18.2/ly/string-tunings-init.ly
/usr/share/lilypond/2.18.2/ly/suomi.ly
/usr/share/lilypond/2.18.2/ly/svenska.ly
/usr/share/lilypond/2.18.2/ly/text-replacements.ly
/usr/share/lilypond/2.18.2/ly/titling-init.ly
/usr/share/lilypond/2.18.2/ly/toc-init.ly
/usr/share/lilypond/2.18.2/ly/vlaams.ly