Please let us know about all possible return code by running sudo and ls on RHEL6

Issue

• Please let us know about all possible return code by running sudo and ls on RHEL6
• How to get all possible return code list from sudo and ls, rather than manpage?
• What "sudo cannot execute the given command" means in SUDO(8) manpage?
• What does manpage SUDO(8) mean by following description?

If sudo cannot stat(2) one or more entries in the user’s PATH an error
is printed on stderr.  (If the directory does not exist or if it is
not really a directory, the entry is ignored and no error is printed.)