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

From	Albretch Mueller <lbrtchx@gmail.com>
Newsgroups	linux.debian.user
Subject	Re: why would "tr --complement --squeeze-repeats ..." append the substitution char once more? ...
Date	2023-12-11 20:00 +0100
Message-ID	<HJTFw-cTrx-9@gated-at.bofh.it> (permalink)
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On 12/11/23, Greg Wooledge <greg@wooledge.org> wrote:
> 1) Many implementations of echo will interpret parts of their argument(s),
>    in addition to processing options like -n.  If you want to print a
>    variable's contents to standard output without *any* interpretation,
>    use printf.
>
>     printf %s "$myvar"
>     printf '%s\n' "$myvar"
>

 I will use "printf ..." from now on.

> 2) As tomas already told you, the square brackets in
>
>     tr -c -s '[A-Za-z0-9.]' _
>
>    are literal.  You're using a command which will keep left and right
>    square brackets in the input, *not* replacing them with underscores.
>    This may not be what you want.

 My mistake, even though it didn't get in the way of what I was trying
to do. I replaced :alnum: by what I thought it meant and left the
brackets.

> 3) In locales other than C or POSIX, ranges like A-Z are *not* necessarily
>    synonyms for [:upper:].  As I've already mentioned, GNU tr is known to
>    contain bugs, so you're getting lucky here.  The bugs in GNU tr happen
>    to work the way you're expecting, so that A-Z is treated like [:upper:]
>    when it should not be.  If at some point in the future GNU tr is fixed
>    to conform to POSIX, your script may break.
>
>    The correct tr command you should be using if you want to retain
>    accented letters (as defined in your locale) is:
>
>     tr -c -s '[:alnum:].' _
>
>    If you want to discard accented letters, then either of these is OK:
>
>     LC_COLLATE=C tr -c -s '[:alnum:].' _
>     LC_COLLATE=C tr -c -s 'A-Za-z0-9.' _
>

 I like your second one liner much better (LC_COLLATE=C tr -c -s 'A-Za-z0-9.' _)

 I tend to avoid '[:alnum:].' because the intended meaning of
"ALphabetic et NUMeric" characters, even though it depends on the
locale has a strong ASCII accent to it.

> Thus, we come full circle.

 Yes, we did. Thank you, lbrtchx

Thread

why would "tr --complement --squeeze-repeats ..." append the  substitution char once more? ... Albretch Mueller <lbrtchx@gmail.com> - 2023-12-11 04:00 +0100
  Re: why would "tr --complement --squeeze-repeats ..." append the  substitution char once more? ... Greg Wooledge <greg@wooledge.org> - 2023-12-11 04:40 +0100
    Re: why would "tr --complement --squeeze-repeats ..." append the  substitution char once more? ... Albretch Mueller <lbrtchx@gmail.com> - 2023-12-11 09:10 +0100
      Re: why would "tr --complement --squeeze-repeats ..." append the  substitution char once more? ... <tomas@tuxteam.de> - 2023-12-11 09:40 +0100
        Re: why would "tr --complement --squeeze-repeats ..." append the  substitution char once more? ... Albretch Mueller <lbrtchx@gmail.com> - 2023-12-11 12:30 +0100
          Re: why would "tr --complement --squeeze-repeats ..." append the  substitution char once more? ... tomas@tuxteam.de - 2023-12-11 13:00 +0100
          Re: why would "tr --complement --squeeze-repeats ..." append the  substitution char once more? ... Greg Wooledge <greg@wooledge.org> - 2023-12-11 13:40 +0100
        Re: why would "tr --complement --squeeze-repeats ..." append the  substitution char once more? ... Greg Wooledge <greg@wooledge.org> - 2023-12-11 13:50 +0100
          Re: why would "tr --complement --squeeze-repeats ..." append the  substitution char once more? ... <tomas@tuxteam.de> - 2023-12-11 14:20 +0100
            Re: why would "tr --complement --squeeze-repeats ..." append the  substitution char once more? ... Greg Wooledge <greg@wooledge.org> - 2023-12-11 14:30 +0100
              Re: why would "tr --complement --squeeze-repeats ..." append the  substitution char once more? ... Albretch Mueller <lbrtchx@gmail.com> - 2023-12-11 15:10 +0100
                Re: why would "tr --complement --squeeze-repeats ..." append the  substitution char once more? ... Max Nikulin <manikulin@gmail.com> - 2023-12-11 16:00 +0100
                Re: why would "tr --complement --squeeze-repeats ..." append the  substitution char once more? ... Greg Wooledge <greg@wooledge.org> - 2023-12-11 16:00 +0100
                Re: why would "tr --complement --squeeze-repeats ..." append the  substitution char once more? ... <tomas@tuxteam.de> - 2023-12-11 16:10 +0100
                "echo" literally in sh scripts (was: why would "tr --complement --squeeze-repeats ..." append the substitution char once more? ...) Stefan Monnier <monnier@iro.umontreal.ca> - 2023-12-11 16:20 +0100
                Re: "echo" literally in sh scripts (was: why would "tr --complement  --squeeze-repeats ..." append the substitution char once more? ...) Greg Wooledge <greg@wooledge.org> - 2023-12-11 18:00 +0100
                Re: why would "tr --complement --squeeze-repeats ..." append the  substitution char once more? ... Albretch Mueller <lbrtchx@gmail.com> - 2023-12-11 20:00 +0100
  Re: why would "tr --complement --squeeze-repeats ..." append the  substitution char once more? ... debian-user@howorth.org.uk - 2023-12-11 19:20 +0100

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