Question

How to print “-n”, “-e” or “-neeenen” from bash (without a newline at the end, without invoking of external programs)?

Q="-n"

echo -n "$Q" # fail

echo -- "$Q" # fail

cat <<< "$Q" # fail, also starts external program

printf -- '%s' "$Q" # success, but starts external program

Answer 1

In bash, printf is a builtin, so no external program is invoked.

$ help printf 
printf: printf [-v var] format [arguments]

printf formats and prints ARGUMENTS under control of the FORMAT.
FORMAT
is a character string which contains three types of objects: plain
characters, which are simply copied to standard output, character
escape
sequences which are converted and copied to the standard output, and
format specifications, each of which causes printing of the next
successive
argument. In addition to the standard printf(1) formats, %b means
to
expand backslash escape sequences in the corresponding argument, and %q
means to quote the argument in a way that can be reused as shell input.
If the -v option is supplied, the output is placed into the value of the
shell variable VAR rather than being sent to the standard output.