PowerPoint Presentation

Linux Basics

Part 1

OSU Picture Greg Keene

Introductions

Lance Albertson

Greg Lund-Chaix

source: http://shesawake.com/

Goals for this Talk

Linux Overview

Linux distributions

System overview

More detail: permissions, processes, package management, services

GREG

Ask audience about their experience level.

Linux Overview

Unix-like operating system

Free, open source software

Runs servers, desktops, phones, tablets, network equipment and more.

GREG

History of UNIXGNU/BSD

Linux Statistics

Supercomputers
More than 90% of thetop 500

Number of distributions
More than 350

Number of developers
1,000 developers contributed in 2010

Number of commits to linux kernel last year
195,579 commits in 2010

GREG

Supercomputers source: http://www.top500.org/overtime/list/32/osDistro count:http://futurist.se/gldt/Number of devs & commits:http://www.linuxfoundation.org/docs/lf_linux_kernel_development_2010.pdf

covers 2.6.11 though 2.6.35

1 commit every 3 minutes, 24/7/365

Linux Distributions

Packaging of applications around a Linux kernel

Different distributions have different target audiences

Distribution lifecycles vary

source: http://www.guilfordlug.org

LANCE

Common Linux Distributions

Fedora / RedHat Enterprise / CentOS

Debian / Ubuntu / Mint

Gentoo / Arch

source: http://www.guilfordlug.org

LANCE

Fedora RHEL rpm based. 18mo. Release cycle for fedora, X years of support for each major RHEL version

Debian Ubuntu deb based. Debian is community based, Ubuntu is based off of debian, targets ease of use for end-user. Has short and long-term supported releases

Gentoo ebuild based, much more customizable, but can be more difficult to deploy/maintain

Choosing a Distribution

Server/desktop/other

Existing infrastructure

Admin experience

Support contract

Release supported lifetime

LANCE

Fedora RHEL rpm based. 18mo. Release cycle for fedora, X years of support for each major RHEL version

Debian Ubuntu deb based. Debian is community based, Ubuntu is based off of debian, targets ease of use for end-user. Has short and long-term supported releases

Gentoo ebuild based, much more customizable, but can be more difficult to deploy/maintain

Linux System Overview

source:wikipedia

LANCE

bash: Bourne Again SHell

Default shell on Linux

Originally based off of the Bourne Shell (sh)

Learn it, live it, love it

GREG

Bash is the default shell on Linux machines

Explain architecture: built in commands vs. external binaries

Quick overview of filesystem, ie. Full vs. relative paths

Basic bash commands

ls *.txtfile1.txt file2.txt file3.txt

ls *.txt > list

for i in `cat list`; do cp "$i" "$i".bak ;done

ls *.txt*file2.txt file1.txt.bak file2.txt file2.txt.bak file3.txt file3.txt.bak

GREG

Demo commands:Directory movement and file manipulation: Cd, pwd, ls, rm, mv, touchUser info: id, whoami, w

Pipes, redirection (pipe.txt, redirect.txt)

Special variables: $?, $$ (pid.sh), !!, !*, !$

Documentation

Most packages include man pages for documentation

More extensive than the --help flag on CLI

Stored in different 'sections'

Picture Flickr user 'bobeirasa'

GREG

Users and Groups

Users and groups are stored in /etc/passwd and /etc/group

Each user name and group name is linked to a number (UID/GID)

UID 0 = root

0-99 typically used for system/service accounts

GREG

File Permissions

Three roles: user (file owner), group, other (world)

Three permissions: read, write, execute

Picture Flickr user 'amagil'

GREG

root user

root user = full access to everything on the system

sudo, su change user

Don't use root user unless you have to!

Comic: http://xkcd.com/149/

GREG

Components of a process

PID: Process ID number

PPID: Parent PID

UID & EUID: real & effective user ID

GID & EGID: real & effective group ID

Niceness

Control terminal

LANCE

Signals

Sent to procs as communication

Sent to terminal driver to kill, interrupt, or suspend

Sent by admin to kill

Sent by kernel

Picture Flickr user 'atomicshark'

LANCE

Signals: Types you should know

HUP, INT, QUIT, KILL, BUS, SIGV, TERM, STOP, TSTP, CONT, WINCH, USR1, USR2

Can catch, block, or dump core?

BUS & SEGV error signals

KILL & STOP cannot be blocked

WINCH term emulators

LANCE

ps: monitor processes

primary tool for monitoring processes

differ between UNIX's

show PID, UID, priority, control term, memory, status, etc

complex over the years, archaic

pstree

LANCE

top: monitor in real-time

big picture in real time

refreshes every 2-3 seconds

kill, renice, sort, memory, etc.

htop even better

color, prettier, more configurable

Picture United Artists from 'Hackers'

LANCE