Introduction to Unix (CA263) Getting Started By Tariq Ibn Aziz

Objectives After reading this chapter, you should be able to: –Understand the computing environment in which you will practice –Practice your first Unix session by logging on and off your computer network –Experiment with a few Unix commands to develop a “feel” for Unix –Acknowledge responsibilities and concern of computer use

The Unix Language ASCII, American Standard Code for Information Interchange Originally, ASCII used only 7 bits (0 and 1) providing 128 characters Extended ASCII uses 8 bits to store 256 characters. For example English letter “H” has a decimal code 72. In term of bits, H is

Case Sensitivity Unix is case sensitive. So beware of Shift and CapLock.

Control Characters Many command employ control characters. The beep, sound that computer make, is signifies as ^G. Activate ^G by holding down control and press G. A useful control character is ^L, which usually clear your window. To correct error use Backspace, or ^H Pressing ^C usually cancels command, its “kill” control sequence. If not respond then use ^Z as a last ditch to suspend your command. Suspended processes linger and thus consume system memory. Sometime ^D (exit) can help, it might log you out.

Syntax and Semantics Writing command correctly and in a specific spelling and order (syntax). If you made error in writing statement you will get syntax error. The choice of usage and meaning (semantics)

Logging In The username, also referred as login name, user account, or user ID is typically chosen for you and is usually abstracted from your real name. Your password is special combination of characters, number, and symbols that you create to protect your account.

Command Window Command Prompt, is used to enter UNIX command. You are running a shell, which is a program that will interpret your instructions for Unix. Unix usually comes with three shell, Bourne and Korn shell uses the dollar sign ($), while C shell uses the (%) sign. Your system might be customized with entirely different prompt. Cursor, used to type commands

Command Window Command Line, place where you type command using cursor and terminate command by pressing Enter key Editing the command, Before press Enter you can edit the command line. Use Backspace or Delete to correct error. Typically ^A and ^E which put you at the beginning and end of the command line.

Command Options Unix command has the following form: – command options arguments –For example print command lp (laser printer) has one option d (for destination), which has it’s own argument, the printer name hp2040 and command argument Data.txt. –$>lp –d hp2040 data.txt

Command Options Unix command has the following form: – command options arguments –who is a command has a command option am I, which modify the behavior of who, restricting its report to only your identity. –$>who am i

Finding Help There’s a special Unix command called man, which means manual. To find help on a particular command, enter man command –$> man lp

Finding your shell The shell is a UNIX program that helps you to communicate with Unix’s core program. The shell run on the top of UNIX’s core. To determine your current shell, enter echo $SHELL. The dollar sign ($) tells Unix to look of the value of SHELL, which is an environment variable. –$> echo $SHELL

Logout With C–shells the command log out will end your session. In GUI environment you must choose a menu option such as exit, log out, or KillTWM.

Error Message If you make mistake, Unix will usually respond with an error message: –$> sl –sl: command not found

Protecting Your Account Change your password –$> passwd –Passwd: Changing password for taziz –Old password: –New password: –Re-enter new password: –$>

Fun With Unix What’s Today –$> date –Sat Mar 26 13:43:21 EST 2008

Unix Command Cal, On what day were you born –$> cal Banner, Print big version in ASCII –$> banner TARIQ Finger, to see who is sharing my last name –$> finger aziz Lynx, a text based web browser –$> lynx (Type G for go)

Unix Command History will show your previous commands –$>History Repeat 10 th Commandyou used before –$>!10 Customizing some of the command name alias customname command –$>alias dir ls –$>dir –UnixBook Mail Courses –$>ls –UnixBook Mail Courses

Compound Commands In Unix, the semicolon (;) can connect two command lines. –$> who am i; who

Piping in Unix Pipe one command’s output into another –$> who | wc –l –$> ls | wc -l

Command Summary aliascustomize a command banneroutput an big sized message calshow calendar dateshow current date echooutput the value of a variable fingeroutput information about a user historyshow commands recently entered lpprint hard copy lslist file lynxinvoke text-based Web browser manfind help on a Unix command moreview contents of text file passwdreset Unix password scinvoke spreadsheet calculator timeshow current time wccount words in a file whoshows users currently logged on