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About A.P. Lawrence

A.P. Lawrence provides SCO Unix and Linux consulting services http://www.pcunix.com
Virtual Tape

Virtual tape does just what you’d think: a backup thinks it’s writing to tape, but in reality the data is going elsewhere. It may still end up on tape eventually, but in the meantime it’s heading for disk, local or otherwise. This stuff isn’t cheap, but then neither are the systems where people would be interested in it.

The Cost of Linux

Matt Asay’s AC/OS blog says that one of the “expenses” noted in Microsoft TCO studies is the cost of training.

Windows vs. Unix – the Forgotten Facts (An Opinion)

“Windows Beat Unix, But It Won’t Beat Linux” makes some valid points, but I think it leaves out one very important thing.

When All Other Explanations Fail..

An article in Wired titled Mind over Matter discusses some researchers who claim that human thought can have effects upon physical events – such as falling ping pong balls and other things.

Mozilla Suite, Seamonkey, huh?

OK, apparently some of the Firefox developers aren’t happy. I don’t follow this stuff closely, and probably wouldn’t understand their complaints anyway.

Bash Aliases

Most shells have some provision for aliases. Aliases can assign default behavior to a command (for example “rm” is often aliased to “rm -i”) or can be used to create new commands (a typical example is “ll” aliased to be “ls -l”).

Bash In-process Regular Expressions

Bash acquired in-process regular expressions in version 3.0, but I never noticed, probably because most of the machines I’m using are Bash 2.05b.

Lies and Statistics – the Unix Server Market

“There are three types of lies – lies, damn lies, and statistics.” The source of that truth seems to be unknown, but it’s sure on the mark for statistics reported in the Unix server market.

Personal Dictionary for Ispell

Ispell works well, but it has to be the most confused project I’ve ever seen. I started looking into this because I got tired of seeing the same common words pop up for correction and wanted to add those words to some file that would cause Ispell to ignore them.

Creating Perl Modules for Web Sites

When you are writing your own code, you are more apt to use someone else’s module than write your own, unless your project gets fairly large and complex.

Microsoft Likes Unix?

The news from Microsoft is that they will be putting more Unix features into their server offerings according to…

Host, Dig

I tend to use “dig” for DNS lookups, but it’s more habit than anything else. The main page for host says “host is a simple utility for performing DNS lookup” while dig’s brags “Most DNS administrators use dig to troubleshoot DNS problems because of its flexibility, ease of use and clarity of output. Other lookup tools tend to have less functionality than dig.”

Darwin (Mac OS X Open Source)

I have a handful of Boston clients, so around once a month or so, I take the commuter rail train into Back Bay or South Station.

Bitkeeper,git (patch maintenance)

Kernel programmers need to keep track of patches. That’s pretty obvious, but what isn’t immediately obvious to those of us who aren’t kernel developers is just how onerous that task is for Linux kernels.

Perl Range Operator (.. and …)

In a list context, this operator is easy to use and understand:

Bit vector, using Perl vec

A bit vector is just an array of bits; subsets of bits within the bytes have some meaning. That allows more compact storage for certain types of data. For example, if you only needed boolean on-off values, you can store eight values in one byte.

LWP (Library for WWW in Perl)
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If you want to automatically process web pages to extract data, you have a number of tools available. You can bring a web page down to your computer using “curl” or “wget”

Magic Sysrq

The “Magic Sysrequest key” is Alt (left or right Alt key) and Sysrq (up there under Print Screen, next to F12 on most keyboards). To use it, you need to have it enabled in your kernel (CONFIG_MAGIC_SYSRQ).

Loadkeys, Dumpkeys

You can change the output of the console keyboard with loadkeys. It’s an extremely powerful command, and the man page can be confusing, but for simple use (which is often all we need it for), it’s very easy.

getconf

“getconf” returns the value of certain system variables. According to the man page (which you may not have on your system) it queries system configuration variables which are either:

A.P. Lawrence On Pro Perl

In the review copy I read, there still were some unfortunate typos that might confuse someone completely new to Perl. I hope those will be fixed before the actual publication. None of them bothered me, but they could be bad for someone starting with no experience at all.

Samba Problems

It never rains but it pours: I’ve had four Samba call in the past two days. A couple of things to keep in mind as a result of helping those folks:

Basic DNS: PTR Records and Why You Care

A PTR record is what lets someone do a “reverse” DNS lookup – that is, they have your IP address and want to know what your host/domain is. At any Unix/Linux command line, you can use “dig -x” to do a reverse lookup:

Controlling Linux colors in vi (vim)

Because of an old application that apparently partially looks at termcap and partially hard-codes terminal info, a customer has to set TERM=ansi when using Alphacom to access his Linux box.