Re: Odd behavior with various (q) array modifiers and non-printable characters (backspace, newline)

[Zach Riggle <zachriggle@xxxxxxxxx>]

Apologies for resurrecting this thread, but I wanted to revisit and thank everybody for the help.

I ran into some issues where my print-a-$-and-then-the-minally-quoted-version-of-this-array-of-scalars when dealing with regex, due to "builtin echo" treating '\bfoo bar\b' incorrectly.

I attempted a variety of things to fix the problem, but going back through this thread really helped a bunch.  I had written additional code that relied in builtin echo.  "command echo" and the issue is resolved.

On Sat, Aug 14, 2021 at 10:52 AM Daniel Shahaf <d.s@xxxxxxxxxxxxxxxxxx> wrote:

Lawrence Velázquez wrote on Wed, Aug 11, 2021 at 17:42:09 -0400:
> On Wed, Aug 11, 2021, at 5:16 PM, Bart Schaefer wrote:
> > You need to stop testing things with "echo".  The "echo" builtin
> > interprets some backslash escapes itself, which will confuse you about
> > what the quoting options have done.
> >
> > Repeat all your tests instead with
> >   printf "%s\n" ${(q)...}
> > and so on, and come back if you still have questions.
>
> Additionally, \b and \n are not interpreted in double quotes, so
> your initial data does not actually contain BS or NL characters.
⋮
> As per the QUOTING section of zshmisc(1):
>
>       Inside double quotes (""), parameter and command substitution
>       occur, and `\' quotes the characters `\', ``', `"', `$',
>       and the first character of $histchars (default `!').

There are third-party plugins that implement syntax highlighting at the
prompt (I happen to co-maintain one such plugin).  Those plugins are
aware of the quoted docs section, so on input such as
.
    % foo "bar \n \\ \x"
.
they will correctly highlight only the «\\» as an escape sequence, and
everything else as literals.