Linux Basics

Linux Basics
By
SATHISHKUMAR G
(sathishsak111@gmail.com)

Roadmap
 What is Unix?
 What is Linux?
 Which Linux Distribution is better?
 Fish vs. Fishing
 Basic Commands
 Vi and Emacs
 Q&A
 References

What is Unix?
 A multi-task and multi-user Operating System
 Developed in 1969 at AT&T’s Bell Labs by
 Ken Thompson (Unix)
 Dennis Ritchie (C)
 Douglas Mcllroy (Pipes - Do one thing, do it well)
 Some other variants: System V, Solaris, SCO
Unix, SunOS, 4.4BSD, FreeBSD, NetBSD,
OpenBSD, BSDI

What is Linux?
 A clone of Unix
 Developed in 1991 by Linus Torvalds, a Finnish
graduate student
 Inspired by and replacement of Minix
 Linus' Minix became Linux
 Consist of
 Linux Kernel
 GNU (GNU is Not Unix) Software
 Software Package management
 Others
http://www.linuxdevices.com/files/misc/ibm-watchpad.jpg

What is Linux?
 Originally developed for
32-bit x86-based PC
 Ported to other
architectures, eg.
 Alpha, VAX, PowerPC,
IBM S/390, MIPS, IA-64
 PS2, TiVo, cellphones,
watches, Nokia N810,
NDS, routers, NAS, GPS,
…
* See references at the end
for the corresponding websites.

Which Linux Distribution is better?
 > 300 Linux Distributions
 Slackware (one of the oldest, simple and stable distro.)
 Redhat
 RHEL (commercially support)
 Fedora (free)
 CentOS (free RHEL, based in England)
 SuSe ( based in German)
 Gentoo (Source code based)
 Debian (one of the few called GNU/Linux)
 Ubuntu (based in South Africa)
 Knoppix (first LiveCD distro.)
 …

Source:
http://futurist.se/gldt/
CentOS
Ubuntu
Knoppix
GentooSlackware
Redhat
Debian

 Ask yourself these questions (from LAH)
 Is it going to be around in 5 yrs?
 Is it giong to stay on top of the latest security
patches?
 Is it going to release updated software promptly?
 If I have problems, will the vendor talk to me?
 Personally, I use Slackware
 But, we will use CentOS (possibly along with
Slackware :)

Fish vs. Fishing
 Manpage
 $ man ls
 $ man 2 mkdir
 $ man man
 $ man -k mkdir
 Manpage sections (LAH
Table 1.2 @ page 12)
 1 User-level cmds and
apps
 /bin/mkdir
 2 System calls
 int mkdir(const char *, …);
 3 Library calls
 int printf(const char *, …);
 4 Device drivers and
network protocols
 /dev/tty
 5 Standard file formats
 /etc/hosts
 6 Games and demos
 /usr/games/fortune
 7 Misc. files and docs
 man 7 locale
 8 System admin. Cmds
 /sbin/reboot
 $ manpath
 $ env | grep MANPATH
 /etc/man.config

Fish vs. Fishing (cont)
 Google
 linux package management -rpm
 “linux package management” -rpm
 linux OR windows
 rpm site:redhat.com
 linux faq filetype:pdf
 Info
 Text-base, menu-based help from GNU
 ?, h, u, t, ^N, ^P, Enter
 $ info info

Basic Commands
 ls
 $ ls -l
 $ ls -a
 $ ls -la
 $ ls -l --sort=time
 $ ls -l --sort=size -r
 cd
 $ cd /usr/bin
 pwd
 $ pwd
 ~
 $ cd ~
 ~user
 $ cd ~weesan
 What will “cd ~/weesan” do?
 which
 $ which ls
 whereis
 $ whereis ls
 locate
 $ locate stdio.h
 $ locate iostream
 rpm
 $ rpm -q bash
 $ rpm -qa
 $ rpm -qa | sort | less
 find
 $ find / | grep stdio.h
 $ find /usr/include | grep stdio.h

Basic Commands (cont)
 echo
 $ echo “Hello World”
 $ echo -n “Hello World”
 cat
 $ cat /etc/motd
 $ cat /proc/cpuinfo
 cp
 $ cp foo bar
 $ cp -a foo bar
 mv
 $ mv foo bar
 mkdir
 $ mkdir foo
 rm
 $ rm foo
 $ rm -rf foo
 $ rm -i foo
 $ rm -- -foo
 chgrp
 $ chgrp bar /home/foo
 chsh
 $ chsh foo
 chfn
 $ chfn foo
 chown
 $ chown -R foo:bar /home/foo

 tar
 $ tar cvfp lab1.tar lab1
 gzip
 $ gzip -9 lab1.tar
 untar & ungzip
 $ gzip -cd lab1.tar.gz | tar xvf –
 $ tar xvfz lab1.tar.gz
 touch
 $ touch foo
 $ cat /dev/null > foo
 Pipe
 $ cal > foo
 $ cat /dev/zero > foo
 $ cat < /etc/passwd
 $ who | cut -d’ ‘ -f1 | sort |
uniq | wc –l
 backtick
 $ echo “The date is `date`”
 $ echo `seq 1 10`
 Hard, soft (symbolic) link
 ln vmlinuz-2.6.24.4 vmlinuz
 ln -s firefox-2.0.0.3 firefox

 Disk usage
 $ df -h /
 File space usage
 $ du -sxh ~/
 Advance stuff 
 $ ssh eon who
 $ ssh eon ‘cd .html ; tar cvfp - cs183 | gzip -9c’ | tar
xvfpz -
 $ ssh kilo-1 ‘tar cvfp - /extra/weesan’ | tar xvfp - -C /

Vi
 2 modes
 Input mode
 ESC to back to cmd mode
 Command mode
 Cursor movement
 h (left), j (down), k (up), l (right)
 ^f (page down)
 ^b (page up)
 ^ (first char.)
 $ (last char.)
 G (bottom page)
 :1 (goto first line)
 Swtch to input mode
 a (append)
 i (insert)
 o (insert line after
 O (insert line before)
 Delete
 dd (delete a line)
 d10d (delete 10 lines)
 d$ (delete till end of line)
 dG (delete till end of file)
 x (current char.)
 Paste
 p (paste after)
 P (paste before)
 Undo
 u
 Search
 /
 Save/Quit
 :w (write)
 :q (quit)
 :wq (write and quit)
 :q! (give up changes)

Emacs
 $ emacs
 Cursor movement
 ^f (forward one char.)
 ^b (backward one char.)
 ^a (begin of line)
 ^e (end of line)
 ^n (next line)
 ^p (prev. line)
 ^v (page up)
 alt-v (page down)
 Deletion
 ^d (delete one char)
 alt-d (delete one word)
 ^k (delete line)
 Paste
 ^y (yank)
 Undo
 ^/
 Load file
 ^x^f
 Cancel
 ^g
 Save/Quit
 ^x^c (quit w/out saving)
 ^x^s (save)
 ^x^w (write to a new file)

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