On 1/21/19 11:38 AM, Robert Elz wrote:
> Date: Mon, 21 Jan 2019 09:37:02 -0500
> From: Chet Ramey <[email protected]>
> Message-ID: <[email protected]>
>
> | It's the here-document. Backslashes and double quotes in here documents
> are
> | kind of strange. This is historical sh behavior.
>
> Not so much backslashes, a here doc (this form) is just a double
> quoted string, and \ behaves in it like in any other double quoted
> string - escaping the special chars, and otherwise simply being
> left alone.
>
> What is odd is that even though it is a double quoted string, the
> double quote character is just a character, and has no quoting
> effects at all. And as it is not special, the \" combination is
> simply the two characters \ and ".
>
> This really gets ugly when var expansions (the old forms, not the
> new pattern matching ones, or any of the ones that are not posix
> which bash supports) which was being used in this case. Quoting
> inside a double quoted string, inside a var expansion is bad enough
> on the command line, in a here doc it is just a disaster.
>
> For what it is worth, both bosh and the FreeBSD shell
> produce
>
> \"A\"
> "A"
There's little consistency. The SVR4.2 sh produces the above. Bash and dash
produce
\"A\"
A
ksh93, mksh, and yash produce
"A"
A
Chet
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU [email protected] http://tiswww.cwru.edu/~chet/
