richard@pegasus.com (Richard Foulk) (03/11/90)
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?
Thanks.
--
Richard Foulk richard@pegasus.commerlyn@iwarp.intel.com (Randal Schwartz) (03/12/90)
In article <1990Mar11.130242.11596@pegasus.com>, richard@pegasus (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? I stole this code more-or-less from somewhere. Sorry I don't have the original author's name to give full credit. ################################################## snip snip #!/usr/bin/perl # print the appropriate line from /usr/lib/history # usage: $0 [<]article-ID[>] ... chdir "/r2/usr.lib.news" || # directory for /usr/lib/news die "Cannot chdir to /usr/lib/news ($!)"; dbmopen(HISTDB,"history",0666) || die "Cannot open history.dir/pag ($!)"; open(HIST,"<history") || die "Cannot open history ($!)"; for (@ARGV) { $_ = "<$_>" unless /^<.*>$/; # add brackets if necessary (warn "No such article: $_"), next unless defined $HISTDB{$_ . "\000"}; seek(HIST, unpack('L', $HISTDB{$_ . "\000"}), 0); $_ = <HIST>; print; } ################################################## snip snip print join('',grep(s/.*"(.)".*/$1/,split(/\n/,<<))); Gimme a "J"! Gimme a "u"! Gimme an "s"! Gimme a "t"! Gimme a " "! :-) Gimme an "a"! Gimme an "n"! Gimme an "o"! Gimme a "t"! Gimme an "h"! Gimme an "e"! Gimme an "r"! Gimme a " "! :-) Gimme a "P"! Gimme an "e"! Gimme an "r"! Gimme an "l"! Gimme a " "! :-) Gimme an "h"! Gimme an "a"! Gimme a "c"! Gimme a "k"! Gimme an "e"! Gimme an "r"! Gimme a ","! :-) What's that spell?? -- /=Randal L. Schwartz, Stonehenge Consulting Services (503)777-0095 ==========\ | on contract to Intel's iWarp project, Beaverton, Oregon, USA, Sol III | | merlyn@iwarp.intel.com ...!any-MX-mailer-like-uunet!iwarp.intel.com!merlyn | \=Cute Quote: "Welcome to Portland, Oregon, home of the California Raisins!"=/
tchrist@convex.COM (Tom Christiansen) (03/12/90)
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!"
lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall) (03/13/90)
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.
Larryjwc@unify.uucp (J. William Claypool) (03/16/90)
In article <7383@jpl-devvax.JPL.NASA.GOV> lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall) writes: >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? >or some such, depending on your news system. For a longer example see the >refetch script I posted a while back. Of course, if you built cnews with dbz all bets are off. -- Bill Claypool +1 916 920 9092 | I know what I know if you know what I mean jwc@unify.UUCP |-------------------------------------------- ...!{csusac,pyramid}!unify!jwc | SCCA SFR Solo II 74 es 1984 CRX 1.5