introduction to unix (ca263) getting started
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Introduction to Unix (CA263)
Getting Started
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 01001000
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 user ahmed
– 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 10 1923
• 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 10th Command you 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• alias customize a command• banner output an big sized message• cal show calendar• date show current date• echo output the value of a variable• finger output information about a user• history show commands recently entered• lp print hard copy• ls list file• lynx invoke text-based Web browser• man find help on a Unix command• more view contents of text file• passwd reset Unix password• sc invoke spreadsheet calculator• time show current time• wc count words in a file• who shows users currently logged on
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