Further tangent: a colleague and I talked about creating a derivative of one of the programmer fonts, replacing smart/curly quotes and another such nuisances with unmistakeable indicators.

This would be a useful feature for any programming font. I can totally imagine writing exploits through zero-width characters; smart insertion into interpreted strings (scanners/parsers) can potentially insert a security leak by an attacker. Though input can come from many places off course, this would at least make one vector visible.

You could probably just invert any non-ASCII character, and you could probably do this programmatically over an existing font.

> `vis`: display non-printable characters in a visual format

Or `cat -v`, the namesake of http://cat-v.org/. :P

what is cat-v.org? (Obviously I visited that link, read the about page - I'm asking for your summary. it's still not clear to me after my initial visit.)

I'm sure there are better people to answer this question, but cat-v.org is the personal blog & collection of interesting stuff by former plan9 personality uriel (sadly no longer with us). It hosts random thoughts and lots of interesting stuff (including man pages) about plan9 and early unix systems, and miscellaneous other unix trivia.

It really is a treasure. Take the time to browse, it's well worth it if you're somewhat interested in unix history and not overly familiar with the subject already.

Thank you, I found your summary helpful and yes I will look through it.

Nostalgic Unix nerds hating on everything that (i) was not in original Unix, or (ii) in Plan9, or (iii) not implemented by authors of these.

Cynical and disingenuous.

Bitterly invidious Lisp nerd?

(They give off rays or something ... took a cursory look to see if I was being unfair, and booom - https://www.gkayaalp.com/blog/20170206_emacs-argument.html )

Yeah that's me :) At least the second part, because with Emacs I don't really need to be invidious.

TBH I do actually like Unix and Plan9, but having read a big part of cat-v website in the past, most of the views there are fanatical, and are more bitter, cynical and disingenuous than I can ever force myself to be. Especially the way incredibly useful and important OSS projects are denigrated and misrepresented is really annoying (see the harmful stuff section, for example).

Well, I apologize and withdraw the 'bitterly invidious', you aren't.

One part is a matter of taste, and having been around both styles, I like better the 'keep it simple' approach. Too many functions/options overload my simple brain ;-)

Do you have any useful commands like these that can handle multi-byte characters in UTF-8? For instance, handling the zero-width space U+200B, which in UTF-8 takes up more than one byte. I've got some custom scripts that do, I was wondering if there was already something out there.

Ooh! I adore `od`, and know too many options for it. But I didn't know about the others. Thanks!

I'll also add my favorite companion to `od` and hexdumps: `man ascii`.

P.S. May we please have a basic Markdown parser for HN?

Is `hexdump` not `xxd`?

`hexdump` is part of util-linux, `xxd` is not. They do the same thing though, up to formatting differences.

And on Debian it's called `hd`.

xxd is part of vim IIRC.

Nope.

https://linux.die.net/man/1/xxd

Yep:

  $ apt-cache show xxd | grep Source:
  Source: vim (2:8.0.1453-1)
  Source: vim

Oh I must've misunderstood what you meant by "part of" vim.

and under emacs whitespace-mode (just in case)