/usr/share/acl2-6.3/books/centaur/bitops/ is in acl2-books 6.3-5.
This file is owned by root:root, with mode 0o755.
..
/usr/share/acl2-6.3/books/centaur/bitops/ash-bounds.o
/usr/share/acl2-6.3/books/centaur/bitops/bits-between.o
/usr/share/acl2-6.3/books/centaur/bitops/bitsets-opt-raw.o
/usr/share/acl2-6.3/books/centaur/bitops/bitsets-opt.o
/usr/share/acl2-6.3/books/centaur/bitops/bitsets.o
/usr/share/acl2-6.3/books/centaur/bitops/congruences.o
/usr/share/acl2-6.3/books/centaur/bitops/defaults.o
/usr/share/acl2-6.3/books/centaur/bitops/equal-by-logbitp.o
/usr/share/acl2-6.3/books/centaur/bitops/extra-defs.o
/usr/share/acl2-6.3/books/centaur/bitops/ihs-extensions.o
/usr/share/acl2-6.3/books/centaur/bitops/ihsext-basics.o
/usr/share/acl2-6.3/books/centaur/bitops/install-bit.o
/usr/share/acl2-6.3/books/centaur/bitops/integer-length.o
/usr/share/acl2-6.3/books/centaur/bitops/part-select.o
/usr/share/acl2-6.3/books/centaur/bitops/rotate.o
/usr/share/acl2-6.3/books/centaur/bitops/saturate.o
/usr/share/acl2-6.3/books/centaur/bitops/sbitsets.o
/usr/share/acl2-6.3/books/centaur/bitops/sign-extend.o
/usr/share/acl2-6.3/books/centaur/bitops/signed-byte-p.o
/usr/share/acl2-6.3/books/centaur/bitops/top.o