Re: CVS commit: src/usr.bin/printf

[Valery Ushakov <uwe%stderr.spb.ru@localhost>]

On Sun, Jun 28, 2020 at 21:52:23 +0700, Robert Elz wrote:

>     Date:        Fri, 26 Jun 2020 22:05:05 +0000
>     From:        "Valeriy E. Ushakov" <uwe%netbsd.org@localhost>
>     Message-ID:  <20200626220505.E9030FB28%cvs.NetBSD.org@localhost>
> 
>   | Modified Files:
>   | 	src/usr.bin/printf: printf.1
>   |
>   | Log Message:
>   | Drop redundant quoting in the nested printf example.
> 
> I don't think that is correct, the quotes around 0x0A were obviously
> redundant (and changing it to 0x0a doesn't alter that), but those
> around the $(printf ...) are not - without those the result from the
> command substitution would be subject to field splitting, and if IFS
> happens to contain a \ or an octal digit, bad things will happen.
> 
> In general it is never a good idea to omit quotes around sh word
> expansions except in the cases where you actually want field splitting
> (or pathname expansion, etc) to happen (and sometimes except in the
> contexts where those don't occur anyway, like x=$whatever)
> 
> For the example in question, try running it with IFS=1 or IFS=2
> to see what I mean.

Right, but I'd expect people that actually use IFS with octal digits
or a backslash to also understand and know how to add necessary
quoting in that case.  Though perhaps it makes sense to them back for
pedagogical purposes.

-uwe