Download Basic System Administration

LINUX System Administration
Perspectives, Practices and
Expectations
Eunuchs or UNIX?
System Administration?
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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
Why UNIX?
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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)
Commercial UNIX Versions
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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)
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 1982-3 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.
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
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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(?)
UNIX Structure
shell scripts
system calls
signal handler
device drivers
terminal
disk
User Space
Kernel
Devices
utilities
C programs
compilers
scheduler
swapper
printer
RAM
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
Kernel Subsystems
• Process management
– Schedule processes to run on CPU
– Inter-process communication (IPC)
• Memory management
– Virtual memory
– Paging and swapping
• I/O system
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File system
Device drivers
Buffer cache
Network I/O, protocol stacks
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()
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
Why LINUX?
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“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
Administrivia
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[email protected], 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: HTTP://www.oakton.edu/~rjtaylor and follow
links. Class material always being updated.
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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.
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Who cares, how do I get an A?
Labs: 75%
Midterm, Final:
25%
Got to be there
(Michael Jackson)