Sequin: A powerful little tool for inspecting ANSI escape sequences

> Isn't it true that ANSI sequences can vary depending on the terminal emulator?

Yes, historically, many terminals were not even ANSI compatible. That is why the terminfo database (and its predecessor termcap) exist; for programs to look at the TERM environment variable, use that to look up the terminal’s capabilities in terminfo, and see what the terminal can and cannot do, and then choose to output whatever sequences the terminal does support. Normally, a program uses yet another library, like ncurses, to do this, but you can do it yourself if you want to, like in a shell script or similar. Outputting raw escape codes is wrong, since the correct way is so very easy.

Don't forget to take care about the terminal code pages as well! Thankfully, terminfo tells you which commands to use when you want to print e.g. β, right?

The easy way is to either restrict yourself to ASCII, or to output raw characters in whatever encoding your locale (LC_CTYPE, LANG, etc.) specifies. If you want to get really fancy with ancient terminals, some of them have, for instance, line drawing characters (and, yes, sometimes things like β) hidden behind special escape sequences, which you can, IIRC, look up in terminfo.

So the "correct" way is not that easy, after all.

On the other hand, ignoring ancient terminals and simply pretending everything is color-enabled, VT-220 compatible, UTF-8 aware terminal emulator works well enough™ almost everywhere, including recent versions of Windows (which IIRC don't even have terminfo; not that it'd help since the legacy Windows console uses ioctl()-like interface instead of the escape sequences) — and is actually easy.

Outputting UTF-8 to a UTF-8 locale is not easy? Most of this is automatically handled by appropriate libraries.

I.e. I would expect

  python3 -c 'print("\N{GREEK SMALL LETTER BETA}")'

to just work on any terminal, as Python does the right thing for you.