I would rather check urls with the following method:

  echo -e -n "https://іnstall.example-clі.dev" | python -c 'exec("""import sys, unicodedata\nfor ch in sys.stdin.read():\n  try:\n    print (ch, " ", unicodedata.name(ch))\n  except ValueError:\n    print ("codepoint ", ord(ch))\n""")'

instead of putting my trust in the hundreds of crates in this tool's Cargo.lock not having a supply chain attack.

I use non-Unicode terminal mode (I might prefer to use a terminal emulator that does not support Unicode but you can add fonts for arbitrary character sets (of your choice, so that none are forced) instead) and program the browser to always display URLs as ASCII. So, when I copy the text to the terminal, I get "#" in place of the Cyrillic alphabets.

I think making IDN work the way it does was a mistake. I thought of making IDN with a character set specific for that use (I did think about how it would work) instead of using Unicode or any other existing character sets (none of them are suitable, as far as I am concerned; however, this new IDN character set would potentially be suitable for some other uses such as perhaps package names). Using one character set for everything is not very good, and Unicode is especially bad for this. (Although in my opinion, TRON code is generally better than Unicode, neither TRON code nor Unicode is the one to use for this)

However, there are other problems with paste in the terminal window, but bracketed paste mode can mitigate some of these problems in some cases, it is not entirely helpful.

My terminal "warns" about them thanks to using a bitmap font that has no (significant?) Unicode coverage beyond code points 0 to 255.

The word tirith means guard (or watch) in Sindarin, one of Tolkien's languages from Lord of the Rings. See also Minas Tirith! I really enjoy this utility's name.

A simpler solution: examine the URL displayed in the browser window before copying terminal commands from the page. E.g. "starts with github.com" -> "trusted GitHub UI indicates the repo is the official one for this project" -> "URL points to the official project README" -> "terminal commands are most likely not malicious, and if they are, there's a bigger problem here".

Of course, more secure installation methods should be preferred, but those are not always available. I am simply comparing the provided solution to homograph attacks with another solution to the same problem.

My terminal is set to CP437 and uses a font incapable of rendering anything else.

Then again, I don't blindly pipe directly from the network into the shell either.

Weird that just 3 days ago https://github.com/makalin/preexec was released with almost exactly the same functionality written in Go.

Amusing that the chosen illustrative homograph is "i" and tirith has two...

Handy! I feel like this should be built into the terminal emulator though?