Re: POSIX woes in t7810.87: dash bash or bash dash?

From: Jeff King <peff@peff.net>
Date: Jun 21, 2011, 00:21 UTC
Message-ID: <20110621002114.GA2050@sigill.intra.peff.net>
In-Reply-To: <7vwrgg9j1n.fsf@alter.siamese.dyndns.org>

On Mon, Jun 20, 2011 at 04:31:32PM -0700, Junio C Hamano wrote:

Show 11 quoted lines

> >> +	cat >expected <<-EOF &&
> >> +	hello.c:	printf("Hello world.\n");
> >> +	EOF
> >
> > Do you need to quote EOF to suppress expansion in the here document?
> > Both bash and dash seem to pass unknown backslash-escapes like "\n"
> > through unharmed, but I don't know if that is portable (they do both
> > munge known escapes like "\\", of course).
> 
> I do not think that is strictly necessary, as we are not in the corner of
> non-portable echo behaviour anymore, but I guess it wouldn't hurt.

I think my brain is fried from using too many almost-shell-compatible quoting languages. For example, unknown escape sequences in C get their backslash removed and the sequence used literally (at least by gcc; I couldn't find anything definite in C99 on this).

But actually, POSIX is quite clear that a backslash before anything besides:

  $   `   "   \   <newline>

is just a backslash, and gets included literally.

-Peff