/usr/share/acl2-7.1/books/hacking/ is in acl2-books 7.1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/acl2-7.1/books/hacking/all.o
/usr/share/acl2-7.1/books/hacking/bridge.o
/usr/share/acl2-7.1/books/hacking/defcode.o
/usr/share/acl2-7.1/books/hacking/defstruct-parsing.o
/usr/share/acl2-7.1/books/hacking/doc-section.o
/usr/share/acl2-7.1/books/hacking/dynamic-make-event-test.o
/usr/share/acl2-7.1/books/hacking/dynamic-make-event.o
/usr/share/acl2-7.1/books/hacking/evalable-ld-printing.o
/usr/share/acl2-7.1/books/hacking/hacker.o
/usr/share/acl2-7.1/books/hacking/hacking-xdoc.o
/usr/share/acl2-7.1/books/hacking/progn-bang-enh.o
/usr/share/acl2-7.1/books/hacking/raw.o
/usr/share/acl2-7.1/books/hacking/redefun.o
/usr/share/acl2-7.1/books/hacking/rewrite-code.o
/usr/share/acl2-7.1/books/hacking/subsumption.o
/usr/share/acl2-7.1/books/hacking/table-guard.o