At least on the x86 architecture, shared libraries are not entirely madeup of position independent code. This means that there is a certainamount of relocation that you have to do when you load a shared libraryinto memory at run time. The basic idea behind prelinking is to try todo this relocation ahead of time; for each shared library, you pick adefault location in memory and 'prelink' it so that if it is loaded atthat location it doesn't need any run-time relocation

The other problem with certified email asa way to solve the spam problem is a basic idea:

People don't pay for what they don't need.

So ask yourself: who actually needs to pay for a certification that theiremail isn't spam?

Significant sources of good email certainly don't need to pay; peoplealready want email from them and will raise heck if stuff startsgetting blocked. No one can afford to block GMail, for example.

There's some motivation for smaller sources

Consider a fileserver and SAN environment where you have a number offrontend NFS fileservers and a number of backend SAN disk units, with atleast as many backend disk units as fileservers. The obvious sensibleway to split the disk units among the fileservers is to have each SANunit used by only one fileserver, because that makes various things mucheasier to manage.

(You might even be tempted to design an infrastructure around theassumption that disk units won't be shared.)

The problem with staying this way is that

Right from the early days of vendor provided Unix, two things wererelatively obvious to people: first, you were going to need to adda bunch of local programs to make the system really useful to yourusers, and second, adding local programs to vendor areas like /bin or /usr/bin was a pretty sure road to doom and disaster. So peoplestarted putting them somewhere else.

(The most famous example is that BSD Unix put a bunch of their additionsin /usr/ucb , which then