Teach Yourself UNIX - PUCP

1 Dave TaylorJames C. Armstrong, YourselfUNIXin 24 Hours201 West 103rd StreetIndianapolis, Indiana 46290 Teach Yourself unix in 24 HoursivPresident, Sams PublishngRichard K. SwadleyPublishing ManagerDean MillerDirector of Editorial ServicesCindy MorrowDirector of MarketingKelli SpencerProduct Marketing ManagerWendy GilbrideAssistant Marketing ManagersJen Pock, Rachel WolfeDecimilli accipitrae Raptor Regina. JATo the newest light of my life: Ashley Elizabeth. DTCopyright 1997 by Sams PublishingFIRST EDITIONAll rights reserved. No part of this book shall be reproduced, stored in aretrieval system, or transmitted by any means, electronic, mechanical, photo-copying, recording, or otherwise, without written permission from thepublisher.

2 No patent liability is assumed with respect to the use of the informa-tion contained herein. Although every precaution has been taken in thepreparation of this book, the publisher and author assume no responsibility forerrors or omissions. Neither is any liability assumed for damages resulting fromthe use of the information contained herein. For information, address SamsPublishing, 201 W. 103rd St., Indianapolis, IN Standard Book Number: 0-672-31107-0 Library of Congress Catalog Card Number: 97-661982000 99 98 974 3 2 1 Interpretation of the printing code: the rightmost double-digit number is theyear of the book s printing; the rightmost single-digit, the number of the book sprinting.

3 For example, a printing code of 97-1 shows that the first printing ofthe book occurred in in AGaramond and MCPdigital by Macmillan Computer PublishingPrinted in the United States of AmericaAll terms mentioned in this book that are known to be trademarks or servicemarks have been appropriately capitalized. Sams Publishing cannot attest to theaccuracy of this information. Use of a term in this book should not be regardedas affecting the validity of any trademark or service EditorGrace M. BuechleinDevelopment EditorBrian-Kent ProffittProduction EditorKristi HartIndexerGreg PearsonTechnical ReviewerRaj MangalEditorial CoordinatorsMandi RouellKatie WiseTechnical Edit CoordinatorLynette QuinnResource CoordinatorDeborah FrisbyEditorial AssistantsCarol AckermanAndi RichterRhonda Tinch-MizeCover DesignerTim AmrheinBook DesignerGary AdairCopy WriterDavid ReichweinProduction TeamSupervisorsBrad ChinnCharlotte ClappProductionBrad LenserChris LivengoodGene ReddingJanet SeibOverviewIntroductionxviHour 1 What Is this unix Stuff?

4 12 Getting onto the System and Using the Command Line213 Moving About the File System434 Listing Files and Managing Disk Usage635 Ownership and Permissions876 Creating, Moving, Renaming, and Deleting Files and Directories1137 Looking into Files1278 Filters and Piping1459 Wildcards and Regular Expressions16110 Power Filters and File Redirection18711An Introduction to the vi Editor19912 Advanced vi Tricks, Tools, and Techniques24513An Overview of the emacs Editor28114 Introduction to Command Shells30515 Getting the Most Out of the C Shell32316 Basic Shell Programming34717 Job Control36118 Printing in the unix Environment37919 Searching for Information and Files39720 Communicating with Others40721 Using Netscape To See the World Wide Web42522 Internet E-Mail, Netnews, and IRC44323 Using telnet and ftp47924 Programming in C for UNIX509 Glossary531 Index541 Teach Yourself unix in 24 HoursviContentsHour 1 What Is This unix Stuff?

5 1 Goals for This Hour .. 1 What Is unix ? .. 2A Brief History of unix .. 3 The C Programming Language .. 4 unix Becomes Popular .. 5 What s All This About Multiuser Systems? .. 5 Cracking Open the Shell .. 6 Getting Help .. 7 Task : Man Pages, unix Online Reference .. 7 Task : Other Ways to Find Help in unix .. 14 Summary .. 17 Workshop .. 17 Key Terms .. 17 Questions .. 18 Preview of the Next Hour .. 192 Getting onto the System and Using the Command Line21 Goals for This Hour .. 21 Task : Logging In and Out of the System .. 22 Task : Changing Passwords with 25 Task : Picking a Secure Password.

6 26 Task : Who Are You? .. 28 Task : Finding Out What Other Users Are Loggedin to the System .. 30 Task : What Is Everyone Doing on the Computer? .. 31 Task : Checking the Current Date and Time .. 33 Task : Looking at a Calendar .. 33 Simple Math with unix .. 36 Task : Using the bc Infix Calculator .. 36 Task : Using the dc Postfix Calculator .. 38 Summary .. 40 Workshop .. 40 Key Terms .. 40 Questions .. 41 Preview of the Next Hour .. 413 Moving About the File System43 Goals for This Hour .. 43 What a Hierarchical File System Is All About .. 44 Task : The unix File System Organization .. 45 The bin Directory.

7 46 The dev Directory .. 47 The etc Directory .. 47 The lib Directory .. 47 The lost+found Directory .. 48 The mnt and sys Directories .. 48 The tmp Directory .. 48 The usr Directory .. 48 Other Miscellaneous Stuff at the Top Level .. 49 How Mac and PC File Systems Differ from the unix File System .. 50 Directory Separator Characters .. 50 The Difference Between Relative and Absolute Filenames .. 51 Task : Hidden Files in unix .. 52 Task : The Special Directories . and .. 55 Task : The env Command .. 56 Task : PATH and 57 Task : Find Where You Are with 58 Task : Move to Another Location with 58 Summary.

8 60 Workshop .. 60 Key Terms .. 60 Questions .. 62 Preview of the Next Hour .. 624 Listing Files and Managing Disk Usage63 Goals for This Hour .. 63 The ls Command .. 64 Task : All About the ls Command .. 64 Task : Having ls Tell You More .. 65 Task : Combining Flags .. 68 Task : Listing Directories Without Changing Location .. 69 Special ls Command Flags .. 71 Task : Changing the Sort Order in 71 Task : Listing Directory Trees Recursively in 73 Task : Long Listing Format in 74 Permissions Strings .. 74 Task : Long Listing Format for Directories in 75 Task : Creating Files with the touch Command.

9 78 Task : Check Disk-Space Usage with 79 Task : Check Available Disk Space with 82 Task : Shrink Big Files with the compress Program .. 83 Summary .. 84 Workshop .. 84 Key Terms .. 84 Questions .. 85 Preview of the Next Hour .. 85 Teach Yourself unix in 24 Hoursviii5 Ownership and Permissions87 Goals for This Hour .. 87 Task : Understand File Permissions Settings .. 88 Task : Directory Permissions Settings .. 93 Task : Modify File and Directory Permissions with 96 Task : Set New File Permissions with 98 Task : Calculating Numeric Permissions Strings .. 102 Task : Establish Default File and Directory Permissionswith the umask Command.

10 104 Task : Identify Owner and Group for Any File or Directory .. 107 Task : Change the Owner of a File or Directory .. 108 Task : Change the Group of a File or Directory .. 109 Summary .. 110 Workshop .. 110 Key Terms .. 110 Questions .. 111 Preview of the Next Hour .. 1116 Creating, Moving, Renaming, and Deleting Filesand Directories113 Goals for This Hour .. 113 Task : Creating New Directories Using 114 Task : Copying Files to New Locations Using 116 Task : Moving Files to New Locations Using 118 Task : Renaming Files with 119 Task : Removing Directories with 120 Task : Removing Files Using 121 Task : Minimizing the Danger of the rm Command.