INTRODUCTION TO LINUX

CS 11 Lab

Introduction to Computer Science

Cheza Marie R. Vianzon

Lecturer

History of Linux

Mid 1980's

Richard Stallman & Free Software Foundation has developed functional alternatives to every major UNIX component except the kernel

1991

Linus Torvalds at the University of Helsinki (Finland) developed the original Linux kernel

March 1992

Linux v1.0 was officially released

History of Linux

1992 onwards

Red Hat Linux – most commonly used distribution

Slackware – offers the full range of expected utilities, tools, and applications

Caldera OpenLinux – comes into two editions: eDesktop 2.4 (workstations) and eServer 2.3 (servers)

S.u.S.E. Linux – popular Linux distribution available in Europe

Debian/GNU – offers more than 3950 software packages using its own package-management system

Corel – newest major Linux distribution; explicitly targeted as a replacement for Microsoft Windows on desktop

File System

Linux has a hierarchical, unified filesystem

Supports 256-character filenames

All command line entries are case sensitive

Uses slash '/' and not backslash '\'

Four types of files

Ordinary files

Directories

Links

Special device files

Prompt

Login as root → machinename:~#

Login as user → machinename:~$

Tilde charcater (~)

Represents home directory

Appended to the end of a filename, which means a backup of a file that has been edited

Shell Account

echo $SHELL

Bourne Shell - /bin/sh

Bourne Again Shell - /bin/bash

Korn shell - /bin/ksh

C-shell - /bin/csh

10 Basic Linux Commandsm

an – Unix manual

ls – lists files

pwd – shows what directory you are in

cd – changes directory

more – shows the contents of text files

whereis – same with 'find' and 'locate'

vi – editing program

grep – extracts info from files

chmod – change file permission

rm – delete file

LAN and Internet Exploration Tools

● telnet – allows you to login remotely from a remote computer to a host server running any linux or linux clone system

● who – shows you who else is currently logged in on you ISP's LAN

● netstat – all sorts of statistics on your LAN, including all Internet connections

● whois – get lots of info on Internet hosts outside your LAN

● nslookup – get a whole bunch more info on other Internet hosts

LAN and Internet Exploration Tools

● dig – even more info on Internet hosts

● finger – get you valuable info about users on other Internet hosts

● ping – to find out if a distant computer is alive and run diagnostic tests

● traceroute – maps Internet connections, reveals routers and boxes running firewalls

● ftp – use it to upload and download files to and from other computers

Listing Directories

● List files in alphabetical order

● Useful options:

– '-a' lists all files, including hidden files– '-A' lists all files, except the current and parent

directory– '-c' sorts file by time (oldest first)– '-d' lists only the name of a directory, not its contents– '-l' lists in long format (permissions and other details)

Listing Directories

● Other useful options:

– '-r' lists in reverse order– '-t' sorts files by time (newest first)– '-x' lists all files across the page instead of in

columns● Current directory (.)

● Parent directory (..)

Permissions

● Read, write, or execute a file or command in a directory

● chmod

– Numeric system● chmod 764 SomeFile

– Symbolic system● chmod g+x SomeFile

Wildcards

● Three types

– Asterisk (*)● Any number of characters anywhere in the

filename– Question mark (?)

● Single character– Brackets ([ ])

● Specific characters

Processes

● Shell acts as the intermediary between the user and the operating system

● Shell can run multiple commands at one time

● Shell can run commands in the background

● Multiple requests to the shell are called processes

● Use 'ps' to list the current processes

● Use 'kill' to stop a process

Using the VI editor

● Two modes– Insert

● Everything you type appears in the document at the place where the blinking cursor is

– Command● Keystrokes perform special functions rather than actually inserting text to the document

Running an Executable File in Linux

● Create a C program i.e. Hello.c

● Compile

– gcc -o Hello Hello.c● Execute/Run

– ./Hello