The following reply was made to PR bin/51269; it has been noted by GNATS.
From: David Holland <dholland-bugs%netbsd.org@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc:
Subject: Re: bin/51269: pkg_info enhancements
Date: Sun, 31 Jul 2016 18:39:14 +0000
On Sun, Jun 26, 2016 at 06:25:00PM +0000, Joerg Sonnenberger wrote:
>>>> * Allow for querying of more than one variable at a time, by specifying
>>>> multiple -Q options
>>>>
>>>> pkg_info -Q PKGPATH -Q PKGNAME
>>>
>>> So, how would I know where one variable ends and the next one starts?
>>
>> Uh, with getopt?
>
> In the output, not on the command line.
One per line, same as in +BUILD_INFO? That won't work if there are
multiple values for one of the variables, but that's not the common
case.
Also, right now if you run the above example with two -Q options
pkg_info silently prints nothing, which does not seem like it's better
behavior.
>>>> * Allow querying for a list of packages that have a variable set, and/or
>>>> packages that have a variable set to a specific value (and maybe even
>>>> a third variant to get a list of packages that do _not_ set the
>>>> variable).
>>>>
>>>> pkg_info -V variable_name
>>>> pkg_info -V variable_name=value
>>>> pkg_info -V \!variable
>>>
>>> Given that this can be trivally written as shell loop, I don't see the
>>> point. [...]
>>
>> "Because shell loops suck" seems like a reason.
>
> Then use awk or Python or Perl or whatever.
...which does not avoid needing O(n) invocations of pkg_info.
> > You're really giving the impression of looking for excuses not to
> > change anything :-|
>
> I've been looking at improving the interface in the past. Most
> approaches apart very easily, so are of very limited use for the
> complexity they add.
I agree that making up a simple ad-hoc query language isn't a good
idea (it should be a simple principled query language) but I don't
agree that it's a silly or non-useful thing to do.
I long ago gave up on trying to use pkg_info as the interface to
/var/db/pkg; it's too hard to do anything useful. It's much easier to
write e.g.
grep -h variable_name= /var/db/pkg/*/+BUILD_INFO
grep -h variable_name=value /var/db/pkg/*/+BUILD_INFO
grep -hL variable_name= /var/db/pkg/*/+BUILD_INFO
plus some output filtering. Not only do you not need to argue with
what pkg_info is willing to do this way, but it uses standard tools
and techniques.
If you/we want people to use pkg_info instead of doing this sort of
thing, it needs to be better at data retrieval.
--
David A. Holland
dholland%netbsd.org@localhost