On Thu, Nov 03, 2022 at 05:20:52PM -0400, Greg Wooledge wrote:
> On Fri, Nov 04, 2022 at 04:09:10AM +0900, Koichi Murase wrote:
> > When one wants to also support Bash 4.2, one possible workaround is to
> > assign the result to a variable (without quoting the right-hand side
> > of the assignment):
> >
> > $ bash-4.2 -c 'string=\"hi\"; string=${string//\"/\"}; echo "$string"'
> > $ bash-4.2 -c 'str="a string"; rep="a&b"; str=${str//a/"$rep"}; echo "$str"'
> >
> > These work as expected in all Bash versions I can test (2.0..5.2).
>
> That's amazingly clever. You're forcing the semantics of double-quoting
> the right-hand side (implicitly, due to the simple assignment), without
> putting actual quotes in it.
Hmm, no, you *are* including quotes, so that's not why it works.
I actually have no idea why it works. But that's OK. I'm just happy
that it *does* work.
So far, that makes two cases where a temporary variable is the only
known workaround for incompatible changes introduced in bash 5.2:
parameter expansion with search-and-replace, and associative array
element access within an arithmetic context.
