1. LINUX System Administration
Perspectives, Practices and Expectations

2. Eunuchs or UNIX?

3. System Administration?
General user administration
Disk administration
Application Administration
Scripting and automation
Security
Network
Performance – CPU, memory, disk, network
Application installation, configuration and maintenance
System software installation, configuration and maintenance
OS installation, configuration and maintenance
Virtualization
Storage/Backup/Restore
Hardware selection and design
Architectural design
Platform Interface

4. Why UNIX? Technical strengths – Common platform, commands and services
The original “portable” OS
Multi-user OS
Disk/process oriented
Highly configurable
Basis of most modern open source technologies and platforms – File Systems, Inter-process communication, script languages, “C” language, Language roject Packaging (IDEW/SCCS) Regex, Internet – TCP/IP, MAC OSx (BSD) , IBM and Windows UNIX Services
Many vendors – software, hardware platforms
At some level not proprietary? (snicker)

5. Commercial UNIX Versions
IBM AIX
SunOS, Solaris
Ultrix, Digital Unix (DEC/Compaq))
HP-UX
Irix (SGI)
SCO (Inte)
UnixWare -> Novell -> SCO -> Caldera ->SCO
Xenix: -> SCO
OSF Standardization (Posix, X/Open, OSF-1)
Coherent (RIP)

6. UNIX Source Code License
Developed in 1960’s on DEC PDP with 6 bit hardware. Later ported to AT&T 3B hardware for automated switching systems.
Internal development continues. BSD developed at UC Berkley in mid-70’s by Ken Thompson and Bill Joy with features like “vi”, TCP/IP.
After internal and academic distribution, AT&T enters computer business in with System III after AT&T breakup. Commercial variants expand Sun, IBM, HP and smaller vendors. PC development leads to SCO – only Intel based commercial version.
System V and BSD continue parallel development until terminal versions AT&T SVR4 and BSD4.3 LINUX in late 1980’s. BSD “Tahoe”, “Reno” versions continue into early 90’s.
USL passws from AT&T Bell Labs, Lucent/Alcatel, Caldera, Novell (licensed to SCO) and then Attachmate and Microsoft.

7. The SCO Story
1980s: Started by Intel (Santa Cruz Operations). Only Intel based commercial UNIX
1980s-1990s: Post AT&T breakup, USL changes hands several time winding up with Novell. “Licenses” USL to SCO.
March 2003: SCO sues IBM for $3 billion. Alleges contributions to Linux come from proprietary licensed code. AIX is based on System V r4, now owned by SCO?
Aug 2003: Evidence released. Some code traced to Ancient UNIX but isn’t in 90% of all running Linux distributions. Suspect code dropped from Linux in July
Aug 2005: Linux Kernel Code May Have Been in SCO
- 2009: Lawsuit proceeds supported by “patent trolls”
2009 – 2010: Lawsuit dismissed. Goodbye SCO.
2011: Netware dead. USL sold to Attachmate and Microsoft(?)

8. UNIX Structure User Space Kernel Devices shell scripts utilities
C programs
system calls
compilers
signal handler
scheduler
Kernel
device drivers
swapper
terminal
printer
Devices
disk
RAM

9. What is the kernel? The kernel is …
a program loaded into memory during the boot process, and always stays in physical memory.
responsible for managing CPU and memory for processes, managing file systems, and interacting with devices.
The Operating System
Microkernel architecture, HAL

10. Kernel Subsystems Process management Memory management I/O system
Schedule processes to run on CPU
Inter-process communication (IPC)
Memory management
Virtual memory
Paging and swapping
I/O system
File system
Device drivers
Buffer cache
Network I/O, protocol stacks

11. System Calls to OS Interface to the kernel – microkernel level 3
Over 1,000 system calls available on Linux
3 main categories
File/device manipulation
e.g. mkdir(), unlink()
Process control
e.g. fork(), execve(), nice()
Information manipulation
e.g. getuid(), time()

12. System call in code The kernel implements a set of special routines
A user program invokes a routine in the
kernel by issuing a hardware TRAP
The trap switches the CPU into a
privileged mode and the kernel executes the
system call
The CPU goes back to user mode
A C language API exists for all
system calls

13. Why LINUX? “Free” open source via GPL with all the UNIX advantages
Multitude of available software
Multi-vendor support some even commercial level (i.e. RedHat)
Desktop of the future? (see Android)
Few proprietary competitors (i.e. Apple, IBM, Novell)
Even fewer *NIX competitors – SCO (dead), Open/Free BSD
Few viable Intel based competitors, even fewer ARM based competitors
“Frozen” USL at System V R4
Proprietary UNIX hardware/software vendors falling by the wayside
Convergence of hardware and software platforms
Services not systems - “the cloud”
New technologies – Android, Redhat, Centos, Ubuntu
Basis for a lot of other proprietary technologies - database frontends, network appliances

14. Administrivia
all day, every day. Or Division II office if necessary.
See syllabus for class schedule
Be on time, eat a good breakfast, it’s a long day, short lunch
Check the website regularly: and follow links. Class material always being updated.
Office hour: Just after class
Labs 75% of grade, attendance is a good idea
Read ahead, online text, supplementary material, Internet reading assignments
Acceptable Use Policy – Systems are on the school and Internet. Personal systems OK, wirelesss is unencrypted. If you wouldn’t do it in front of your mother/wife/girlfriend/kids/significant other/life partner, don’t do it here.
Bad/impolitic/wife/mother-in-law/current event humor OK (see instructor), keep your politics and biases to yourself.
Removeable disc procedures.

15. Who cares, how do I get an A?
Labs: 75%
Midterm, Final: 25%
Got to be there (Michael Jackson)