On 07/25/2011 03:45 PM, Linda Walsh wrote:
I mistyped that but it brings me to an interesting
conundrum:
GLOBAL="hi there"
{foo=GLOBAL echo ${!foo}; }
This says:
evaluate ${!foo}, and pass that expansion to 'echo', with foo=GLOBAL in
the environment of echo. You are invoking behavior that POSIX leaves
undefined (that is, bash is perfectly fine evaluating ${!foo} prior to
assigning foo, but bash would also be okay if it assigned foo prior to
evaluating ${!foo}. Hence, you got no output.
But:
{ foo=GLOBAL;echo ${!foo}; }
> hi there
The extra ; forces the semantics. Here, the assignment to foo is a
different statement than the expansion of of ${!foo}. And while ${!foo}
is a bash extension, it still proves that this is a case where foo was
assigned prior to its use.
Weird...
Not if you think about it properly.
--
Eric Blake ebl...@redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
