September 2006 Archives

If you recognized the first few Bell numbers, you would, of course, have guessed 877 immediately. Otherwise, you would have done like me and headed off to the fantastic On-Line Encyclopedia of Integer Sequences I've just recently discovered. A quick query for:

http://www.research.att.com/~njas/sequences/?q=1+1+2+5+15+52+203

Would take you straight to sequence A00110, also known as "Bell or exponential numbers: ways of placing n labeled balls into n indistinguishable boxes. It can also be expressed as this short formula (among others):

 a(n) = exp(-1)*sum(k=>0, k^n/k!)

I love this, as I've always loved/hated these types of puzzles. And it has many more usefull uses, as is pointed out by their demo.

Another quick Solaris trick to write about before I forget about it.

When used to do:

$> cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 15
model : 4
model name : Intel(R) Xeon(TM) CPU 3.00GHz
stepping : 1
cpu MHz : 2992.785
[...]

Instead, on Solaris, use psrinfo(1M)

$> psrinfo -v
Status of virtual processor 0 as of: 09/17/2006 21:45:32
on-line since 08/24/2006 16:16:03.
The i386 processor operates at 1800 MHz,
and has an i387 compatible floating point processor.
Status of virtual processor 1 as of: 09/17/2006 21:45:32
on-line since 08/24/2006 16:16:07.
The i386 processor operates at 1800 MHz,
and has an i387 compatible floating point processor.

I've always said Solaris was a solid operating system, just a sucky distro. Well, since Sun opened up things, OpenSolaris is making new distributions possible.

There are already 4 listed distros:

• BeleniX
• marTux
• NexentaOS
• SchilliX

Of the 4, I've looked at Nexenta, and it looks like the more serious one. It's Debian/Ubuntu based and it's pretty much in a usable state as it is. It comes with a LiveCD, a VMWare image (cool), and the ordinary install CD. And as they proclaim on their homepage, They have 12029 packages available in their APT repository.

Nothing like being able to :

$> apt-get dist-upgrade

On a solaris box ;-)

Oh, and it comes with ZFS ;-)

No zones yet...

It's a quick and dirty Solaris trick, but I better write it down or I'll forget.

When faced with the annoying question: "And what drives are in this box again?", don't get all confused anymore, and call format(1) to the rescue.

$> format
Searching for disks...done
AVAILABLE DISK SELECTIONS:
       0. c0t0d0 <IBM-DXHS18Y-0430 cyl 8152 alt 2 hd 20 sec 218>
          /pci@1f,4000/scsi@3/sd@0,0
       1. c0t1d0 <IBM-DXHS18Y-0430 cyl 8152 alt 2 hd 20 sec 218>
          /pci@1f,4000/scsi@3/sd@1,0

Certainly not exactly what it was intended for, but it worked for me and I hope I never forget it again.