Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!cs.utexas.edu!usc!elroy.jpl.nasa.gov!jpl-devvax!lwall
From: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Newsgroups: comp.lang.perl
Subject: Re: dbm and news history
Message-ID: <7383@jpl-devvax.JPL.NASA.GOV>
Date: 12 Mar 90 18:27:43 GMT
References: <1990Mar11.130242.11596@pegasus.com>
Reply-To: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 31

In article <1990Mar11.130242.11596@pegasus.com> richard@pegasus.com (Richard Foulk) writes:
: I'm having a little trouble figuring out just how to use the dbm stuff
: in perl.  Can someone give me an example of how to find an entry in
: /usr/lib/news/history given the usual key (e.g. <123@xyz.UUCP>),
: assuming the usual multi-megabyte history{,.pag} files?

Two things you have to realize when accessing the history file (at least
in the news system we're currently using).

First, "<123@xyz.UUCP>" won't be found because the keys are canonicalized
to lower case:

	$key =~ y/A-Z/a-z/;

Second, "<123@xyz.uucp>" won't be found because there's a trailing null as
part of the key.  So you have to say

	$key .= "\0";

Now you should be able to say

	$data = $history{$key}.
	($loc) = unpack('l',$data);
	seek(HIST,$loc,0);
	$histline = <HIST>;
	($messid,$date,$artlist) = split(/\t/,$histline);

or some such, depending on your news system.  For a longer example see the
refetch script I posted a while back.

Larry