Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uunet!convex!convex.COM
From: tchrist@convex.COM (Tom Christiansen)
Newsgroups: comp.lang.perl
Subject: Re: dbm and news history
Message-ID: <100525@convex.convex.com>
Date: 12 Mar 90 12:23:09 GMT
References: <1990Mar11.130242.11596@pegasus.com>
Sender: news@convex.com
Reply-To: tchrist@convex.COM (Tom Christiansen)
Organization: CONVEX Software Development, Richardson, TX
Lines: 38

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?

This should do it -- it's out of my examples suite.

--tom

#!/usr/bin/perl
#
# xpost -- given article id's, check news history dbm file
# 	   for what newsgroups they're in.   shows how to 
#	   use associative arrays and bind them to external files.

$HIST = '/usr/local/lib/news/history';
dbmopen(HIST,$HIST,0666) || die "$0: couldn't dbmopen $HIST: $!\n";
open HIST || die "$0: couldn't open $HIST: $!\n";

foreach $key ( @ARGV ) {
    $key =~ tr/A-Z/a-z/;
    $key = "<$key>" if $key !~ /^<.*>$/;
    $key .= "\000";
    if (!defined $HIST{$key}) {
	print stderr "no article $key\n";
	next;
    } 
    ($pos) = unpack('L',$HIST{$key});
    seek(HIST,$pos,0);
    $line = <HIST>;
    print $line;
} 
--

    Tom Christiansen                       {uunet,uiucdcs,sun}!convex!tchrist 
    Convex Computer Corporation                            tchrist@convex.COM
		 "EMACS belongs in <sys/errno.h>: Editor too big!"