Recently, for my version of recently, a shell history meme has beengoing around various places .Thinking about the meme and what it would look like for me has ledme to thinking about two different usage patterns in Unix graphicalenvironments; I will call these persistent and disposable.

People who follow the persistent pattern like long-lived, multi-purposecontexts; for example, they are inclined to leave a terminal window or ashell session active for a long time, and over its lifetime such a shellwill wind

I was once fairly interested in and involved in anti-spam stuff; I spenta bunch of time on anti-spam precautions here, followed news sources,and so on. These days, I find myself much less involved, and althoughI still care about various spam issues, I don't spend very much timeinvolved with the whole field.

What happened is simple: somewhat to my surprise, the spam problemhere was pretty much solved when we deployed a commercial anti-spamsolution in combination with greylisting

System activity tracers are a hot topic, with the best known one beingSun's DTrace. In thinking about this issue recently, I believe thatthere are three sorts of questions that they can be used to answer,or at least that I'm interested in having answered:

• what is my system doing?

  Performance related tracing is one obvious subset of this, both inthe 'what is taking all the time' sense and in the 'how long doessome operation take' sense.

• why is my system