/usr/share/acl2-8.0dfsg/books/projects/codewalker/ is in acl2-books-source 8.0dfsg-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/acl2-8.0dfsg/books/projects/codewalker/cert.acl2
/usr/share/acl2-8.0dfsg/books/projects/codewalker/codewalker.lisp
/usr/share/acl2-8.0dfsg/books/projects/codewalker/demo-fact-count-up.lisp
/usr/share/acl2-8.0dfsg/books/projects/codewalker/demo-fact-partial.lisp
/usr/share/acl2-8.0dfsg/books/projects/codewalker/demo-fact-preamble.lisp
/usr/share/acl2-8.0dfsg/books/projects/codewalker/demo-fact.lisp
/usr/share/acl2-8.0dfsg/books/projects/codewalker/if-tracker.lisp
/usr/share/acl2-8.0dfsg/books/projects/codewalker/m1-version-3.lisp
/usr/share/acl2-8.0dfsg/books/projects/codewalker/simplify-under-hyps.lisp
/usr/share/acl2-8.0dfsg/books/projects/codewalker/terminatricks.lisp