vis(1) on OpenBSD
The text 53d4392ecb66, as OpenBSD 2.4, OpenBSD 2.3, OpenBSD 2.2, OpenBSD 2.1 shipped it.
display non-printable characters in a visual format
Flags it lists
-
-F -
-b -
-c -
-f -
-l -
-n -
-o -
-s -
-t -
-w