[GLLUG] My recruitment efforts

[Matt Graham]

On Sunday 26 May 2002 11:29, Jane DeBano wrote:
> Sorry, it was actually Jane DeBano sending the message.  Clicking on
> the link got me into Netscape (dreck) with Karen's return address. 
> She's the lead Instructor for the CIT program.

Oops.  (Multi-user machines can be a bit annoying sometimes...)

> I've got from 3 to 6 hours to fill or any portion thereof.  So far,
> Our textbook covers the above theory as it regards UNIX/LINUX.  

OK, memory/processor management are the responsibility of the Unix 
kernel.  On an x86, the kernel uses the processor's protected mode to 
make each user-level process have its own address space.  The kernel 
(in its "stock" mode, without the patches for huge amounts of memory) 
uses a 32-bit address space, 3G of that is for user processes, 1G of 
that is for the kernel itself.  Processes can share segments of memory.

Processor management... The kernel divides time up into timeslices, and 
every time the timer interrupt fires, the kernel checks its scheduler, 
which determines which process gets to use the processor next.  
Processes get timeslices based on their priority--normal user processes 
are at priority 0 (normal) and the superuser (root) can use "nice" to 
increase the priority of a process, up to -20 (extremely high 
priority.)  Users can "nice" a process and decrease its priority down 
to 20 (extremely low priority) meaning the process will get fewer 
timeslices.  Things that take lots of CPU time (running the compiler) 
are typically niced to priority 10, so they don't interfere with the 
users' normal applications too much.  Some people set the X server (the 
thing that handles all the graphics) priority at -10, so it will 
respond faster.

Device management:  Everything is a file, including all the devices 
attached to the system.  So the hard drive that's master on the first 
IDE controller is /dev/hda , the first partition on that hard drive is 
/dev/hda1 , etc.  Access to the devices is controlled by standard Unix 
user and group permissions.  There are 2 types of devices, "block", and 
"character".  

File management:  Typical Linux systems don't store very much metadata 
with the files.  Every file is a single stream of data, unlike MacOS 
which has "resource forks", or WinNT, which can associate metadata with 
a file but usually doesn't.  Each file has a set of permissions 
associated with it, "special", "read", "write", and "execute", and is 
owned by a user and a group.

> What
> I'm looking from a guest speaker is why you are using Linux.  Why are
> you pumped abut Linux?  

I'm using it because it's *fun*.  (Yeah, some people have fun in weird 
ways....)

> What are it's advantages/disadvantages?  What
> can you do with Linux that DOS and Windows can't do?

The main advantages are:

Almost everything that makes up a Linux distro is Open (free as in 
speech), meaning anybody can look at the code and see how the 
professionals and überhackers did things.  This helps those who want to 
do programming, since it gives them a huge base of code to look at and 
get ideas from.  Also, if there's a bug somewhere, a programmer can 
look at the code, figure out where the bug is, and fix it, without 
waiting for the vendor to do it.  (This makes fixing bugs faster and 
should improve software quality.)

Also, almost everything in a Linux distro is Free (free as in beer), 
meaning you can legally redistribute the distro.  One set of Redhat CDs 
can be used to install Redhat Linux on 1 or 1000 machines--no garbage 
about per-seat licensing.  Also, you can get copies of most distros for 
very little money, or for $0.00 if you have a Linux-using friend.

> What applications are most used in Linux?

Depends on the user, really.

> How widespread is its use? 

Nobody really knows.  The Linux Counter counts about 300,000 registered 
users, but the number of actual Linux users is probably 2 to 10 times 
higher.  The number of people who use another OS on their desktops but 
depend on Linux firewalls/fileservers/webservers/database servers on 
the backend is very large.

> Will it come to dominate the world? 

Maybe.

> Enthusiasm and
> some nifty demo's plus info on how to get, setup and use Linux would
> probably substitute for hands-on if it's not feasible to put Linux on
> our machines.  As I said in a previous message, we have 20 student
> computers with a double boot option on Windows 2000 and Win98, so I
> don't think we could boot from a CD.

?  Why not?  Well, they'd have to change a setting in the BIOS, but 
that's it.  I can understand if you don't want to wipe out the previous 
installations of whatever, but there are a number of "live filesystem 
CDs" that you can use.  SuSE has one available--you boot from the CD, 
and it loads a small root filesystem into RAM, then grabs everything 
else it needs from the CD.  IIRC, it creates 3 small files on the hard 
disk that can be deleted after you're done running the live CD.  It's 
very similar to running a real Linux system, just slower.

> Boot from a floppy, yes. Can you create a bootable system floppy in 
> LInux?

http://www.toms.net/rb/ for a very popular and useful miniature Linux 
distro that fits on a floppy.  It's very stripped-down, but still 
powerful.  No GUI, just command-line.  There are other miniature 
distros around, but these tend to be optimized for a specific purpose, 
like Coyote Linux (turn an old 486 into a good firewall with 1 floppy).

Problem is, using these miniature distros is not really for the new 
user.  It'd be best to use the live filesystem CDs or have some people 
bring in already-working Linux machines for the students to bang on, I 
think.

-- 
   First they came for the verbs, and I said nothing because verbing
   weirds language.  Then they arrival for the nouns, and I speech
   nothing because I no verbs.      -- Peter Ellis on afp
There is no Darkness in Eternity/But only Light too dim for us to see