A sed command to display non-visible characters in a text file

I just ran into a need to see what non-printable (non-visible? non-ASCII?) characters were embedded in a text file in a Unix system, when I remembered this old sed command:

sed -n 'l' myfile.txt

Note that the character in that sed command is a lower-case letter "L", and not the number one ("1").

This command shows the contents of your file, and displays some of the non-printable characters with the octal values. On some systems tab characters may also be shown as ">" characters.

Similar to vi binary mode

This is similar to using the cat command, except for the handling of the non-printing characters. You can also see something similar with the vi "binary mode" argument, like this:

vi -b myfile.txt