Re: purposes of quotearg

On 29/05/2026 23:51, Bruno Haible via Gnulib discussion list wrote:
> Hi,
> 
> I would like to document, in quotearg.h, the possible purposes of the
> 'quotearg' module.
> 
> Clearly, not all *_quoting_style styles fulfil all the possible purposes.
> But once we have a list of possible purposes, we can make up the matrix
> which style fulfils which purposes.
> 
> The purposes I can think of are the following:
> 
>    * Avoid ambiguous diagnostics. For instance, if 'E.T.' is the name of
>      a network interface:
>        program: cannot connect to E.T.
>      is ambiguous, whereas
>        program: cannot connect to 'E.T.'
>      is less ambiguous.
> 
>    * Avoid emitting escape sequences that, by virtue of being ANSI
>      escape sequences <https://en.wikipedia.org/wiki/ANSI_escape_code>,
>      may cause trouble in the terminal, including (but not limited to)
>        - displaying fake results,
>        - crashing the terminal.
>      For instance, create a file like this:
>        $ touch `printf 'fooinv\x1b[3Dbar'`
>      Then some diagnostics might make the user think that they are about
>      'foobar'.
> 
>    * Avoid printing characters that are "unprintable" in the terminal's
>      encoding. If that encoding is not UTF-8, they would typically leave
>      no traces on screen, thus end up presenting misleading results.
> 
> Other purposes that I missed?
Avoid printing shell meta-characters,
which may cause side effects if pasted back to a shell command.