Concatenate Non-Printing Characters

I’ve been writing some non-printing characters to a file. But when I concatenate, it appears empty.

cat log.txt
# Nothing here 🥺

cat those non-printing characters with -v:

cat -v log.txt
jjjj:wq^M%

See man cat for these details:

-v      Display non-printing characters so they are
        visible.  Control characters print as ‘^X’ for
        control-X; the delete character (octal 0177) prints
        as ‘^?’.  Non-ASCII characters (with the high bit
        set) are printed as ‘M-’ (for meta) followed by the
        character for the low 7 bits.