September 2006 Archives

What's next ? 1, 1, 2, 5, 15, 52, 203, ???


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:

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.

/proc/cpuinfo on Solaris


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.

A better Solaris Distro


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:

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
       0. c0t0d0 <IBM-DXHS18Y-0430 cyl 8152 alt 2 hd 20 sec 218>
       1. c0t1d0 <IBM-DXHS18Y-0430 cyl 8152 alt 2 hd 20 sec 218>

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

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