Introduction

System Administrator?

• 系統管理員• 不只是 IT

• 管理別人 / 大家使用的系統• http://www.theage.com.au/articles/2002/12/27/1040511172494.h

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工作內容

• 裝機設定 / 更新• 讓機器 / 系統不要掛• 找問題• 引進並整合新科技• 寫文件• 未雨綢繆 - 防災演練• 資訊安全

工作需求

• 能力傾向 (aptitude)

• 快速上手複雜的東西• 掌握東西如何運作• 小心行事• 把東西搞爆了可以很快救回來• 溝通技巧• 品德操守

參考資料• Unix and Linux System Administration Handbook

• Essential System Administration (O'Reilly)

• http://people.cs.nctu.edu.tw/~huanghs/course/sysadm2011/

• http://www.washington.edu/R870/ ( 有點舊 )

• 我們絕對講不完 !!

UNIX Basics

Linux vs *BSD

• 教派問題• 沒有誰比較好• 發展模式不同

o 中央集權o 各自為政

BSD

• FreeBSD, OpenBSD, NetBSD, ....

• Developed by Berkeley(B -> Berkeley)

• Kernel + base + boot loader + ....

• Ports/Packages

Linux

• Kernel

• Distributionso Debian/Ubuntuo Redhat/CentOS/Fedorao SUSEo Slackwareo Gentoo

• Mostly packages

Root is God

• Root can do anythingo Almighty

• Root can do anythingo Protect it wello Be careful what you doo Always logouto Never login as root

Everything is a file

• Typeso Regularo Directorieso Linkso Specials (devices)o Socketso Pipes

• Similar interface for everything

Trees Everywhere

• Paths starts from / (root)

• Processes start from init (PID 1)

File System Structure

• / Root

• /home User homes

• /dev Device files

• /bin Basic programs

• /lib* Basic libraries

• /sbin Basic system programs

• /usr Programs/libraries

• /var System data storage

• /proc Process states

• /sys System states

• http://en.wikipedia.org/wiki/Filesystem_Hierarchy_Standard

File Permissions

• rwx Octal (八進位 )

• r - 4 - read

• w - 2 - write

• x - 1 - execute / search

rwx = 4+2+1 = 7r-x = 4+1 = 5

File Permissions

rwxrwxrwx 1 wens wens 182 Jun 28 16:13 test.c

Others Group

User

File Permissions

• Owner

• Group

• Others

Check the first matching type onlyCheck complete path

Path vs Inode

• Pathpoint in FS to access file

• Inode actual file

• Multiple paths can point to same fileo Hard linko Share metadata

Inode

• Metadata about a fileo Permissionso Dateso Sizeo ...

• Points to disk blocks with content

Basic CommandsKnow them well

Command Prompt

Normal user$ _

Fancywens@linux1:/home$ _

Root# _

Comment (in this document)##

File/Directory ops

• cd• mkdir• rm• mv• ln• cp• chown• chgrp• chmod

man

• Manual

• Manpages notated as cp(1)

• 1 is section

## Lookup “cp”$ man cp

## to be precise$ man 1 cp

## to search for “XXX”$ man -k XXX

su

• Switch user

$ su root## Enter root password

$ su ta217## Enter ta217 password

sudo

• Switch user and do something

• More controlled

• Enter your password

$ sudo lsEnter your passwordrun "ls" as root

ps

• List processes

• man ps for all options

$ ps

$ ps aux

find

• find something

$ find /home -name wens## search for file "wens" under /home

$ find /home -exec ls -l {} \;## search for files in /home and run ls -l {file} for each one

xargs

• Run a command with a list as arguments

$ find | xargs ls –l# Similar to last find example

grep

• Look for lines in files containing a pattern

• Regular expressions!

$ grep printf *.c## look for lines in all .c files with printf

df

• Disk Free

• How much space is free?

$ df

$ df /home

du

• Disk Usage

• How much space is something using?

$ du hello.c## How large is hello.c

$ du ~## How large are the files in my home?

$ du -s ~## How large (total) is my home?

vi

• Vi/Vim

• Text editor

$ vim

$ vim hello.c

$ vimtutor## Tutorial!!

Vim modes

• Command modecommands (duh)

• Insert modetype and see

• Visual modeselection

Vim key commands

• d - delete from here to...

• c - change from here to...

• x - delete 1 (delete key)

• X - delete 1 (backspace)

• y - copy from here to...

• p - paste here

• P - paste before here

• r - replace

• dd - delete line

• yy - copy line

• /XXX - search for XXX

Vim commands

• :e xxx - open xxx

• :e! xxx - open xxx without saving

• :w - save

• :w xxx - save as xxx

• :q - quit

• :q! - quit without saving

Combine!

• :wq - save and quit

回家練習Vimtutor工作站上熟悉指令

(chown, chgrp, su, sudo 除外 )

作業

最後一堂課是經驗分享 /Q&A你想聽什麼 ?

大家 12月見