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Re: Why are hyperlinks blue?

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In comp.os.linux.misc, The Natural Philosopher  <tnp@invalid.invalid> wrote:
> On 29/08/2021 05:21, Rich wrote:
>> Another possibility (for the Python specific question) is that Python
>> simply copied the Unix shell's comment character, which is also a #.

Yeah, # was a common choice of comment character before Python existed,
so need to look back before Python.

>> But then that just moves the question back to: Why do Unix shell
>> comments begin with a "#"?
> Why not?

:r! stty -a |grep erase
	-echoprt -altwerase -noflsh -tostop -flusho pendin -nokerninfo
	erase = ^?; intr = ^C; kill = ^U; lnext = ^V; min = 1; quit = ^\;
	time = 0; werase = ^W;

These days erase defaults to del (^?) or backspace (^H), but I can
remember a time when it defaulted to #, and using your backspace
character as a comment indicator makes it hard to add comments. My 1988
copy of _The Unix Operating System_ (second edition) by Kaare Christian
shows defaults (page 98)

	erase = #, kill = @, intr = ^?

(I remember seeing that kill thing also interfere with use of @ in
passwords.) The book does not show the default for lnext, which is what
you'd need to type to escape the special meaning of # or @ to use it in
comments. There's an explanation that you can use # for comments in
shell scripts (p195), but no explaination for why in that book.

For reference, first release of Python was 1991. First release of Perl,
which also uses # for comments, is 1988. 

Looking around I see a 1967 doc for BCPL using // for comments, very
c++ ish:

https://www.bell-labs.com/usr/dmr/www/bcpl.pdf

The Unix Seventh Edition man pages, in *roff format which I can read
fine but..., are here:

https://s3.amazonaws.com/plan9-bell-labs/7thEdMan/index.html

I see that awk uses # for comments, but shell shows : for comments.
These days, in sh the : command is a substitute for /bin/true. It
works like a no-op command, which is subtly different from a comment:

	#!/bin/sh
	#this is a comment
	:this will like produce ":this: command not found"
	# the following does nothing
	# > /etc/passwd
	: the following will produce an error or destroy your system
	: > /etc/password
	: moral: don't run stuff as root
	# oops, no closing quote!

https://s3.amazonaws.com/plan9-bell-labs/7thEdMan/vol2/awk.txt

   .ND "September 1, 1978"

https://s3.amazonaws.com/plan9-bell-labs/7thEdMan/vol2/shell.bun.txt

   .ds DA 1977 November 1

No stty manpage there to look for control character defaults. Erase,
kill, etc, might not have made sense in early ASR-33 days. I wasn't
there and don't know. BUT probably:

Larry Wall probably used # for comments in Perl because AWK used # for
comments. Guido van Rossum likely used # for comments because languages
like AWK and Perl used # for comments.

Elijah
------
carefully uses : for embeded vi commands in shell scripts sometimes

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Thread

Why are hyperlinks blue? "Andrei Z." <no-email@invalid.invalid> - 2021-08-27 07:25 +0300
  Re: Why are hyperlinks blue? not@telling.you.invalid (Computer Nerd Kev) - 2021-08-28 05:31 +0000
  Re: Why are hyperlinks blue? SixOverFive <hae274c.net> - 2021-08-28 01:32 -0400
    Re: Why are hyperlinks blue? The Natural Philosopher <tnp@invalid.invalid> - 2021-08-28 09:10 +0100
    Re: Why are hyperlinks blue? "Carlos E. R." <robin_listas@es.invalid> - 2021-08-28 13:11 +0200
      Re: Why are hyperlinks blue? Rich <rich@example.invalid> - 2021-08-29 04:21 +0000
        Re: Why are hyperlinks blue? The Natural Philosopher <tnp@invalid.invalid> - 2021-08-29 08:44 +0100
          Re: Why are hyperlinks blue? Eli the Bearded <*@eli.users.panix.com> - 2021-08-29 21:44 +0000
            Re: Why are hyperlinks blue? Richard Kettlewell <invalid@invalid.invalid> - 2021-08-31 20:43 +0100
        Re: Why are hyperlinks blue? Aragorn <thorongil@telenet.be> - 2021-08-29 16:43 +0200
          Re: Why are hyperlinks blue? Richard Kettlewell <invalid@invalid.invalid> - 2021-08-30 08:08 +0100

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