[TAG] need information about sylpheed-claws

[Benjamin A. Okopnik]

On Tue, Apr 12, 2005 at 03:18:59PM -0600, Jason Creighton wrote:
> On Thu, 7 Jul 2005 21:18:06 -0400, 
> "Benjamin A. Okopnik" <ben at linuxgazette.net> wrote:
> 
> > ``
> > ben at Fenrir:/tmp$ dd if=/dev/zero bs=1GB count=1|bzip2 > foo.bz2
> > ben at Fenrir:/tmp$ ls foo*
> > -rw-r--r--  1 ben ben 722 2005-07-07 21:05 foo.bz2
> > ben at Fenrir:/tmp$ mutt -s 'Hi, Karl-Heinz!' -a foo.bz2 kh at somewhere.com < /dev/null
> > ''
> 
> Perhaps apropos of the swap space discussion elsewhere, I tried your
> command, and...
> 
> ``
> ~$ dd if=/dev/zero bs=1GB count=1|bzip2 > foo.bz2
> dd: memory exhausted
> ~$ dd --version
> dd (coreutils) 5.2.1
> Written by Paul Rubin, David MacKenzie, and Stuart Kemp.
 
I've got the same one. 

> Copyright (C) 2004 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions.  There is NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
> ''
> 
> I have 128 megs of RAM, plus 150 or so of swap. Looks like dd tried to
> grab the whole thing at once. You either have a different version of dd
> or a much nicer setup than me. 

Heh. Not necessarily nicer, but I tend to do some large-scale
stuff once in a while, so I tend to prefer to configure it by using a
Mack truck's front bumper as a model.

``
ben at Fenrir:~$ free -tk
             total       used       free     shared    buffers     cached
Mem:        515464     320600     194864          0      23032     117328
-/+ buffers/cache:     180240     335224
Swap:      1951888          0    1951888
Total:     2467352     320600    2146752
''

In other words, 512MB of RAM and a couple of GB of swap (none of which
is being used at the moment, but I've just rebooted after configuring a
shiny new 2.6.11.7 kernel.)


> So for people without that much VM kicking around, you could use:
> 
> ``
> ~$ dd if=/dev/zero bs=1M count=1024 | bzip2 > foo.bz2
> 1024+0 records in
> 1024+0 records out
> ''
> 
> You'd have to use "bs=1MB count=1000" to make the size match Ben's
> command.
 
Right on both counts. I wasn't expecting people to actually *do* this,
just to become aware of it. It _is_ an interesting sort of thing to play
with, though - 1GB shrunk to 700-some _bytes?_ Wow.

> > If you project that kind of compression ratio to, say, 1TB or so, you
> > can see how it might fry an AV utility's little brain... and if Mr.
> > Cracker is lucky, it might totally fill up the partition as well.
> 
> That's just *evil*, Ben. I wish I'd thought of it.

[grin] Me too. I was just riffing off something that a poster on Bugtraq
said a while back; he didn't approach the problem exactly this way, but
it was implicit in his idea. A clever fellow, that one.


* Ben Okopnik * Editor-in-Chief, Linux Gazette * http://linuxgazette.net *