Re: why would "tr --complement --squeeze-repeats ..." append the substitution char once more? ...

[Greg Wooledge <greg@wooledge.org>]

On Mon, Dec 11, 2023 at 09:37:42AM +0100, tomas@tuxteam.de wrote:
>  2. This is tr, not regexp, so '[A-Za-z0-9.]' isn't doing what you
>    think it does. It will match '[', 'A' to 'Z', 'a' to 'z','.' and
>    ']'. I guess you want to say 'A-Za-z0-9.'

Well spotted.

>  3. As a convenience, tr has char classes. Perhaps [:alnum:] is for
>    you. No idea whether this is a GNU extension

It's POSIX.  100% portable, as long as you ignore any bugs in GNU tr.

Looks like GNU tr in Debian 12 still doesn't handle multibyte characters
correctly:

    unicorn:~$ echo 'mañana' | tr ñ X
    maXXana

So... as long as you're working in the C locale, where [:alnum:] is
just the ASCII capital and lowercase letters and digits, you should be
fine.