History expansion modifiers :t, :h, :r and :e break quoting in some cases

History expansion modifiers :t, :h, :r and :e break quoting in some cases

[Axel Beckert]

Hi,

Today I was slightly confused about the "`quote>" prompt after the
following commands:

% echo 'foo/bar'
foo/bar
% echo !$:h
`quote> ^C
echo 'foo
% 

(I manually added the "^C" above where I pressed Ctrl-C. My real-life
case was more complex and had blanks in the file names and hence
qualifies the quoting. :-)

So ":h" seems not only to strip "/bar" as I would have expected but
also strips the trailing single quote.

The same happens with ":e" as well as with ":t" or ":r" and the
leading single quote:

% echo 'foo/bar.bla'
foo/bar.bla
 echo !$:e
`quote> ^C
echo bla'
%

% echo 'foo/bar'
foo/bar
% echo !$:t
`quote> ^C
echo bar'
%

% echo 'foo/bar.bla'
foo/bar.bla
% echo !$:r
`quote> ^C
echo 'foo/bar
%

It also behaves the same way with double quotes instead of single
quotes.

At least for enclosing double and single quotes, I would have expected
that these are not stripped on :t or :h. I can imagine that it may be
harder to implement for more complex quoting variants like

% echo "foo '"'/"'"' bla"
foo '/"' bla
% 

Initially noticed with zsh 4.3.17 in Debian Wheezy, but also
reproducible with zsh 5.0.2 in Debian Unstable.

		Kind regards, Axel
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Re: History expansion modifiers :t, :h, :r and :e break quoting in some cases

[Peter Stephenson]

On Tue, 02 Jul 2013 19:43:56 +0200
Axel Beckert <abe@deuxchevaux.org> wrote:
> Today I was slightly confused about the "`quote>" prompt after the
> following commands:
> 
> % echo 'foo/bar'
> foo/bar
> % echo !$:h
> `quote> ^C
> echo 'foo
> % 
> 
> (I manually added the "^C" above where I pressed Ctrl-C. My real-life
> case was more complex and had blanks in the file names and hence
> qualifies the quoting. :-)
> 
> So ":h" seems not only to strip "/bar" as I would have expected but
> also strips the trailing single quote.

Yes, the history modifiers know essentially nothing about shell syntax.
They are applied very early in processing, before any lexical analysis.

The only workaround I can see that would process the command line more
intelligently would be some function running in the line editor, which
has access to more intelligence, including some existing functions for
analysing command lines.  However, that's not a 5-minute job.

pws