dash and ANSI escape sequences

[Alex Waite <alexqw85@gmail.com>]

I come here in search of someone who understands dash/portable scripting 
better than I do. Today, my Google-foo is failing me.

I am in the process of cleaning up someone else's semi-portable shell 
script (originally written on FreeBSD). The original script uses colors, 
in the form of

echo -e "\e[1;32mpassed\e[0m"

"echo" should be avoided in general and any option passed to "echo" is 
non-portable. In bash, I can easily port this to printf

printf '%b' "\x1b[32;1mpassed\x1b[0m\n"

However, this approach does not work in dash. I have read both the echo 
and printf sections of the dash manual, and it seems that both "\e" and 
"\x" are unsupported. Using "%b" allows additional backslash-escape 
sequences, but only \c and \0.

I know the purpose of dash is to provide an efficient POSIX compliant 
shell. Is there really no POSIX compliant way to use color? It seems 
so... 80s. Dash's manpage does state that it supports "backslash 
notation as defined in ANSI X3.159-1989 (“ANSI C89”)", but I can't find 
a copy of ANSI C89 online to confirm whether it includes display 
attributes. ANSI C89 is old, but still... too old for color?

Am I somehow missing some hidden functionality in printf, or is there 
really no POSIX compliant method of printing colors, or is Dash simply 
incomplete with its POSIX support in this regard?

Any insight is most appreciated.

---Alex