UNIX for Dummies Questions & Answers

Hi everyone,
I am running Debian Wheezy 7.2 with a 3.2.0-4-686-pae kernel. There are a couple of virtual files and directories in /proc I can't seem to find much information about. I am aware that some of them might be legacy, though. Anyway, here they are:

Actually there is a bunch of other files / directories, of which I presume the most important ones are:

In your opinion, am I missing anything?
As a final note, this is in preparation for Exam 101 in LPIC-1.
Any hints or suggestions will be more than welcome.
Thanks in advance.

Maybe...

Sit down, young one, while i tell you a story from the times of yore...

At first, there was UNIX ("UNICS", actually), and one absolutely new paradigma to this OS (and a prominent reason for its success) was the idea that everything is a file. UNIX does most of its workings in files: devices? There is a device file. Inter-process communication? There are named pipes and semaphores and FIFOs. Drivers? Interact with a pseudo device (file)! And so on, and so on.

Now, this was a very simple yet efficient and flexible design, but humans always seek to improve on even the best ideas and so a successor for UNIX was conceived by some of the people who built UNIX: it was called "Plan 9" and it took whatever was good in UNIX and tried to improve on it. One of these improvements was to take the idea of "everything is a file" one step further and do even process accounting in the filesystem: this was the invention of the /proc filesystem.

Well, sometimes even the best laid plans fall short and, sadly enough, this was the case with Plan 9 (from outer space) too - it never gained momentum and it never took off, let alone replaced UNIX. Still, many ideas from Plan 9 were good and have been built (Plan-9-developers would probably say "backported") into various UNIX flavours. The /proc filesystem was such an idea. It was built into the Linux kernel and since then most UNIX-derivates have - under the impression of the Linux success - also incorporated a /proc filesystem. My "home" OS, IBMs AIX, has it since version 5 (~2000). Also SunOS has it, but i don't know since when. I do not know enough about HP-Ux to know if there is a /proc filesystem or not.

I hope this story has enriched your understanding. I know, it will not answer any concrete questions of "how to ..." but i think knowing some historical dimensions of the things we deal with helps us doing better work in the long run.

bakunin

bakunin,
Thank you so very much for taking the time to write this.
Yes, it did not answer my question, but I actually love to learn about the background of things I tend to take for granted.
Thanks again.