/usr/share/acl2-6.3/books/str/ is in acl2-books 6.3-5.
This file is owned by root:root, with mode 0o755.
..
/usr/share/acl2-6.3/books/str/abbrevs.o
/usr/share/acl2-6.3/books/str/arithmetic.o
/usr/share/acl2-6.3/books/str/base64.o
/usr/share/acl2-6.3/books/str/case-conversion.o
/usr/share/acl2-6.3/books/str/cat.o
/usr/share/acl2-6.3/books/str/char-case.o
/usr/share/acl2-6.3/books/str/char-fix.o
/usr/share/acl2-6.3/books/str/coerce.o
/usr/share/acl2-6.3/books/str/defs.o
/usr/share/acl2-6.3/books/str/digitp.o
/usr/share/acl2-6.3/books/str/eqv.o
/usr/share/acl2-6.3/books/str/explode-atom.o
/usr/share/acl2-6.3/books/str/explode-nonnegative-integer.o
/usr/share/acl2-6.3/books/str/fast-cat.o
/usr/share/acl2-6.3/books/str/firstn-chars.o
/usr/share/acl2-6.3/books/str/hexify.o
/usr/share/acl2-6.3/books/str/html-encode.o
/usr/share/acl2-6.3/books/str/ieqv.o
/usr/share/acl2-6.3/books/str/iless.o
/usr/share/acl2-6.3/books/str/iprefixp.o
/usr/share/acl2-6.3/books/str/isort.o
/usr/share/acl2-6.3/books/str/istrpos.o
/usr/share/acl2-6.3/books/str/istrprefixp.o
/usr/share/acl2-6.3/books/str/isubstrp.o
/usr/share/acl2-6.3/books/str/make-character-list.o
/usr/share/acl2-6.3/books/str/natstr.o
/usr/share/acl2-6.3/books/str/pad.o
/usr/share/acl2-6.3/books/str/portcullis.o
/usr/share/acl2-6.3/books/str/prefix-lines.o
/usr/share/acl2-6.3/books/str/stringify.o
/usr/share/acl2-6.3/books/str/strline.o
/usr/share/acl2-6.3/books/str/strnatless.o
/usr/share/acl2-6.3/books/str/strpos.o
/usr/share/acl2-6.3/books/str/strprefixp.o
/usr/share/acl2-6.3/books/str/strrpos.o
/usr/share/acl2-6.3/books/str/strsplit.o
/usr/share/acl2-6.3/books/str/strsubst.o
/usr/share/acl2-6.3/books/str/strtok.o
/usr/share/acl2-6.3/books/str/strval.o
/usr/share/acl2-6.3/books/str/subseq.o
/usr/share/acl2-6.3/books/str/substrp.o
/usr/share/acl2-6.3/books/str/suffixp.o
/usr/share/acl2-6.3/books/str/symbols.o
/usr/share/acl2-6.3/books/str/top.o