Re: Why this expansion doesn't work?

[DervishD <zsh@xxxxxxxxxxxx>]

    Hi Bart :)

 * Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx> dixit:
> On Mar 12, 11:14am, DervishD wrote:
> } Subject: Why this doesn't work?
> As long as I'm passing out netiquette lessons, I might as well say
> that it would be nice if the word "this" in that Subject had been
> replaced by a slightly more descriptive phrase.

    Yes, you're right, but I couldn't think of a more apropriate
subject at the time, sorry O:)) Next time I'll use a better and more
descriptive subject.
 
> }     $ eval printf -- "Hello\\n"
> }     Hello$
> If this is really what you're seeing, then something is indeed wrong.
> What you should see is "Hellon", not "Hello".

    That's weird :(( I still have open the console where I saw that,
but in a new virtual console that doesn't happen and yes, I see
'Hellon' and not 'Hello'. I don't know why, because the options are
the same in both terminals (I've double checked that) :???

    On every new terminal I see 'Hellon'.
 
> }     $ eval printf -- "Hello\\\n"
> }     Hello<newline>
> }     I mean, no newline character is output when using just two
> } backslashes, and I don't understand that.
> Remember that when you use "eval" the command line is actually parsed
> twice.  So
> 	eval printf -- "Hello\\n"
> is equivalent to
> 	printf -- Hello\n
> 
> The first parse removes the quotes and one of the backslashes, and the
> second parse removes the remaining backslash.

    So I must use something like:

    eval printf -- \"Hello\\n\"

    I forgot that the double quotes were removed :((( Is there any
way of seeing how a command line is parsed *just before* being
executed by the shell? That would avoid the stupidity from the user
(that is, me) you can see above O:) I've tried the eval command with
the double quotes quoted and works perfectly ;)

    Thanks a lot for answering, Bart, and my excuses for the poor
subject O:)

    Raúl Núñez de Arenas Coronado

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