Bruce Momjian <bruce@momjian.us> writes:
> On Fri, Oct 21, 2011 at 05:31:41PM -0400, Robert Haas wrote:
>> I'm not sure whether that's a bug per se, but I can see where a
>> behavior change might be an improvement.
> I did some research on this and learned a little more about flex rules.
> Turns out we can allow variable substitution in psql whole-line
> commands, like \copy and \!, by sharing the variable expansion flex
> rules with the code that does argument processing.
Well, it'd be nice to allow substitution there ...
> What we can't easily do is to allow quotes to prevent variable
> substitution in these whole-line commands because we can't process the
> quotes because that will remove them.
... but if there is then no way to prevent it, that's absolutely
unacceptable.
regards, tom lane