The Most Useful UNIX Guide for Mac OS X Users Ever, with Hundreds of High-Quality Examples!
Beneath Mac OS® X's stunning graphical user interface (GUI) is the most powerful operating system ever created: UNIX®. With unmatched clarity and insight, this book explains UNIX for the Mac OS X user—giving you total control over your system, so you can get more done, faster. Building on Mark Sobell's highly praised A Practical Guide to the UNIX System, it delivers comprehensive guidance on the UNIX command line tools every user, administrator, and developer needs to master–together with the world's best day-to-day UNIX reference.
This book is packed with hundreds of high-quality examples. From networking and system utilities to shells and programming, this is UNIX from the ground up—both the "whys" and the "hows"—for every Mac user. You'll understand the relationships between GUI tools and their command line counterparts. Need instant answers? Don't bother with confusing online "manual pages": rely on this book's example-rich, quick-access, 236-page command reference!
Don't settle for just any UNIX guidebook. Get one focused on your specific needs as a Mac user!
A Practical Guide to UNIX® for Mac OS® X Users is the most useful, comprehensive UNIX tutorial and reference for Mac OS X and is the only book that delivers
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The GNU-Linux Connection 2
The Heritage of Linux: UNIX 5
What Is So Good About Linux? 6
Overview of Linux 10
Additional Features of Linux 15
Chapter Summary 16
Conventions Used in This Book 22
Logging In 24
Working with the Shell 25
Curbing Your Power: Superuser Access 28
Getting the Facts: Where to Find Documentation 29
More About Logging In 35
Chapter Summary 38
Advanced Exercises 39
Special Characters 42
Basic Utilities 43
Working with Files 45
| (Pipe): Communicates Between Processes 52
Four More Utilities 53
Compressing and Archiving Files 56
Locating Commands 61
Obtaining User and System Information 63
Communicating with Other Users 67
Chapter Summary 69
Advanced Exercises 73
The Hierarchical Filesystem 76
Directory and Ordinary Files 77
Working with Directories 88
Access Permissions 91
Chapter Summary 102
Advanced Exercises 105
The Command Line 108
Standard Input and Standard Output 113
Running a Program in the Background 125
Filename Generation/Pathname Expansion 127
Chapter Summary 133
Advanced Exercises 136
Tutorial: Creating and Editing a File with vim 141
The compatible Parameter 148
Introduction to vim Features 148
Command Mode: Moving the Cursor 154
Input Mode 158
Command Mode: Deleting and Changing Text 160
Searching and Substituting 164
Miscellaneous Commands 170
Yank, Put, and Delete Commands 171
Reading and Writing Files 174
Setting Parameters 175
Advanced Editing Techniques 180
Units of Measure 184
Chapter Summary 188
Advanced Exercises 194
Tutorial: Getting Started with emacs 198
Basic Editing Commands 204
Online Help 209
Advanced Editing 212
Language-Sensitive Editing 225
Customizing emacs 235
More Information 240
Chapter Summary 241
Advanced Exercises 250
Shell Basics 257
Parameters and Variables 277
Controlling bash Features and Options 318
Processing the Command Line 322
Chapter Summary 332
Advanced Exercises 336
Shell Scripts 340
Entering and Leaving the TC Shell 341
Features Common to the Bourne Again and TC Shells 343
Redirecting Standard Error 349
Working with the Command Line 350
Control Structures 368
Chapter Summary 381
Advanced Exercises 384
Programming in C 388
Using Shared Libraries 396
make: Keeps a Set of Programs Current 399
Debugging C Programs 407
System Calls 417
Source Code Management 420
Chapter Summary 430
Advanced Exercises 432
Control Structures 436
File Descriptors 470
Parameters and Variables 474
Builtin Commands 487
Shell Programs 510
Chapter Summary 520
Advanced Exercises 524
Language Basics 530
Advanced gawk Programming 554
Error Messages 559
Chapter Summary 560
Advanced Exercises 561
Editor Basics 565
Chapter Summary 578
Standard Multiplicative Suffixes 586
Common Options 587
The sample Utility 587
sample: Very brief description of what the utility does 588
aspell: Checks a file for spelling errors 589
at: Executes commands at a specified time 593
bzip2: Compresses or decompresses files 596
cal: Displays a calendar 598
cat: Joins and displays files 599
cd: Changes to another working directory 601
chgrp: Changes the group associated with a file 603
chmod: Changes the access mode (permissions) of a file 604
chown: Changes the owner of a file and/or the group the file is associated with 608
cmp: Compares two files 610
comm: Compares sorted files 612
configure: Configures source code automatically 614
cp: Copies files 616
cpio: Creates an archive or restores files from an archive 619
crontab: Maintains crontab files 624
cut: Selects characters or fields from input lines 627
date: Displays or sets the system time and date 630
dd: Converts and copies a file 633
df: Displays disk space usage 636
diff: Displays the differences between two files 638
du: Displays information on disk usage by file 644
echo: Displays a message 647
expr: Evaluates an expression 649
file: Displays the classification of a file 653
find: Finds files based on criteria 655
finger: Displays information about users 661
fmt: Formats text very simply 664
fsck: Checks and repairs a filesystem 666
ftp: Transfers files over a network 671
gcc: Compiles C and C++ programs 678
grep: Searches for a pattern in files 683
gzip: Compresses or decompresses files 688
head: Displays the beginning of a file 691
kill: Terminates a process by PID 693
killall: Terminates a process by name 695
less: Displays text files, one screen at a time 697
ln: Makes a link to a file 702
lpr: Sends files to printers 705
ls: Displays information about one or more files 708
make: Keeps a set of programs current 715
man: Displays documentation for commands 721
mkdir: Creates a directory 724
mkfs: Creates a filesystem on a device 725
Mtools: Uses DOS-style commands on files and directories 728
mv: Renames or moves a file 732
nice: Changes the priority of a command 734
nohup: Runs a command that keeps running after you log out 736
od: Dumps the contents of a file 737
paste: Joins corresponding lines from files 742
pr: Paginates files for printing 744
ps: Displays process status 746
rcp: Copies one or more files to or from a remote system 750
rlogin: Logs in on a remote system 752
rm: Removes a file (deletes a link) 753
rmdir: Removes a directory 755
rsh: Executes commands on a remote system 756
scp: Securely copies one or more files to or from a remote system 758
sleep: Creates a process that sleeps for a specified interval 760
sort: Sorts and/or merges files 762
split: Divides a file in into sections 771
ssh: Securely executes commands on a remote system 773
strings: Displays strings of printable characters 777
stty: Displays or sets terminal parameters 778
tail: Displays the last part (tail) of a file 783
tar: Stores or retrieves files to/from an archive file 786
tee: Copies standard input to standard output and one or more files 791
telnet: Connects to a remote system over a network 792
test: Evaluates an expression 794
top: Dynamically displays process status 798
touch: Changes a file's access and/or modification time 801
tr: Replaces specified characters 804
tty: Displays the terminal pathname 807
tune2fs: Changes parameters on an ext2 or ext3 filesystem 808
umask: Establishes the file-creation permissions mask 810
uniq: Displays unique lines 812
w: Displays information about system users 814
wc: Displays the number of lines, words, and bytes 816
which: Shows where in PATH a command is located 817
who: Displays information about logged-in users 819
xargs: Converts standard input into command lines 821
Simple Strings 828
Special Characters 828
Bracketing Expressions 832
The Replacement String 833
Extended Regular Expressions 834
Appendix Summary 835
Solving a Problem 838
Finding Linux-Related Information 839
Specifying a Terminal 844
yum: Updates and Installs Packages 848
Apt: An Alternative to yum 850
A Practical Guide to UNIX® for Mac OS® X Users explains how to work with the UNIX operating system that is the foundation of Mac OS X. This book looks “under the hood,” past the traditional graphical user interface (GUI) that most people think of as a Macintosh, and explains how to use the powerful command line interface (CLI) that connects you directly to UNIX.
Command line interface (CLI). In the beginning UNIX had a command line (textual) interface. There was no mouse to point or icons to drag and drop. Some programs, such as emacs, implemented rudimentary windows using the very minimal graphics available in the ASCII character set. In addition, reverse video helped separate areas of the screen. UNIX was born and raised in this environment.
Naturally all of the original UNIX tools were invoked from the command line. The real power of UNIX, and of Mac OS X, lies in this environment, which explains why many UNIX professionals work exclusively from the command line.
Using clear descriptions and lots of examples, this book shows you how to get the most out of your UNIX-based Mac OS X system using the command line interface. The first few chapters quickly bring readers with little computer experience up to speed. The rest of the book is appropriate for more experienced computer users.
Audience. This book is designed for a wide range of readers. It does not require programming experience, but assumes a basic familiarity with the Macintosh GUI. It is appropriate for the following readers:
Benefits. A Practical Guide to UNIX® for Mac OS® X Users gives you an in-depth understanding of how to use the UNIX operating system that is the foundation for Mac OS X.
A large amount of free software has always been available for Macintosh systems. In addition, the Macintosh shareware community is very active. By introducing the UNIX aspects of Mac OS X, this book throws open to Macintosh users the vast store of free and low-cost software available for UNIX, Linux, and other UNIX-like systems.
Regardless of your background, this book offers the practical knowledge you need to get on with your work: You will come away from this book understanding how to use the UNIX operating system that underlies OS X, and this text will remain a valuable reference for years to come.
This book is organized for ease of use in different situations. For example, you can read it from cover to cover to learn about the UNIX aspects of Mac OS X from the ground up. Alternatively, once you are comfortable using OS X, you can use this book as a reference: Look up a topic of interest in the table of contents or index and read about it. Or, refer to one of the utilities covered in Part VI, “Command Reference.” You can also think of this book as a catalog of Mac OS X topics: Flip through the pages until a topic catches your eye. If you are familiar with UNIX or a UNIX-like operating system such as Linux, refer to Appendix C, “Mac OS X for UNIX Users,” which lists some of the differences between Mac OS X and traditional UNIX systems. The book also includes many pointers to Web sites where you can get additional information: Consider the Web an extension of this book.
A Practical Guide to UNIX® for Mac OS® X Users offers these features:
This section describes the information that each chapter covers and explains how that information can help you take advantage of the power of Mac OS X. You may want to review the table of contents for more detail.
Presents background information on Mac OS X. This chapter covers the history of Mac OS X, explains the connection between OS X and open-source software including GNU and BSD software, and discusses some of OS X’s important features that distinguish it from other operating systems including other versions of UNIX.
Tip: Experienced users may want to skim Part I
If you have used a UNIX-like system before, you may want to skim or skip some or all of the chapters in Part I. All readers should take a look at “Conventions Used in This Book” (page 18), which explains the typographic conventions that this book uses, and “Getting the Facts: Where to Find Documentation” (page 27), which points you toward both local and remote sources of Mac OS X documentation.
Part I introduces UNIX on a Mac OS X system and gets you started using it from the command line.
Explains the typographic conventions that this book uses to make explanations clearer and easier to read. This chapter provides basic information and explains how to log in, display a shell prompt, give OS X commands using the shell, and find system documentation.
Explains the command line interface (CLI) and briefly introduces more than 30 command line utilities. Working through this chapter gives you a feel for UNIX and introduces some of the tools you will use day in and day out. Chapter 3 also introduces pipes, which allow you to combine utilities on the command line. The utilities covered in this chapter include
Discusses the OS X hierarchical filesystem from a UNIX perspective, covering files, filenames, pathnames, working with directories (folders), access permissions, and hard and symbolic links. This chapter also discusses extended attributes including file forks, attribute flags, type codes, creator codes, and Access Control Lists (ACLs). Understanding the filesystem allows you to organize your data so that you can find information quickly. It also enables you to share some of your files with other users while keeping other files private.
Explains how to use shell features to make your work faster and easier. All of the features covered in this chapter work with both the Bourne Again Shell (bash) and the TC Shell (tcsh). This chapter discusses
Part II covers two classic, powerful UNIX command line text editors. Mac OS X includes the vimtext editor, an “improved” version of the widely used vi editor, as well as the popular GNU emacs editor. Text editors enable you to create and modify text files that can hold programs, shell scripts, memos, and input to text formatting programs.
Starts with a tutorial on vim and then explains how to use many of the advanced features of vim, including special characters in search strings, the General-Purpose and Named buffers, parameters, markers, and execution of commands from vim. The chapter concludes with a summary of vim commands.
Opens with a tutorial and then explains many of the features of the emacs editor as well as how to use the META, ALT, and ESCAPE keys. The chapter also covers key bindings, buffers, and incremental and complete searching for both character strings and regular expressions. In addition, it details the relationship between Point, the cursor, Mark, and Region. It also explains how to take advantage of the extensive online help facilities available from emacs. Other topics covered include cutting and pasting, using multiple windows and frames, and working with emacs modes—specifically C mode, which aids programmers in writing and debugging C code. Chapter 7 concludes with a summary of emacs commands.
Part III goes into more detail about bashand introduces the TC Shell (tcsh).
Picks up where Chapter 5 leaves off, covering more advanced aspects of working with a shell. For examples it uses the Bourne Again Shell—bash, the shell used almost exclusively for system shell scripts. Chapter 8 describes how to
Describes tcsh and covers features that are common to and differ between bash and tcsh. This chapter explains how to
Discusses networks, network security, and the Internet. This chapter
Discusses core system concepts including Superuser and the use of sudo as well as system operation. This chapter
Part V covers programming under Mac OS X. It discusses the C programming environment, the use of bash as a programming language, and ways to write programs using awk and sed.
Introduces Mac OS X’s exceptional programming environment. This chapter focuses on the traditional UNIX command line development environment because this environment is the one you will likely have to work in with free software developed for UNIX systems. This chapter
Once you have mastered the basics of OS X, you can use your knowledge to build more complex and specialized programs, by using the shell as a programming language. Chapter 13 shows you how to use bash to write advanced shell scripts. It discusses
Chapter 13 poses two complete shell programming problems and then shows you how to solve them step by step. The first problem uses recursion to create a hierarchy of directories. The second problem develops a quiz program and shows you how to set up a shell script that interacts with a user and how the script processes data. (The examples in Part VI also demonstrate many features of the utilities you can use in shell scripts.)
Explains how to write programs using the powerful awk language that filter data and write reports. The advanced programming section describes the powerful getline statement, which gives you better control over bringing data into awk, and the system statement, which allows you to run external commands from within an awk program.
Describes sed, the noninteractive stream editor that finds many applications as a filter within shell scripts. This chapter discusses how to use sed’s buffers to write simple yet powerful programs and includes many examples.
Mac OS X includes hundreds of utilities. Chapters 14 and 15 as well as Part VI provide extensive examples of the use of more than 90 of the most important utilities with which you can solve problems without resorting to programming in C. If you are already familiar with UNIX, this part of the book will be a valuable, easy-to-use reference. If you are not an experienced user, it will serve as a useful supplement while you are mastering the earlier sections of the book.
Although the descriptions of the utilities in Chapters 14 and 15 and Part VI are presented in a format similar to that used by the Mac OS X manual (man) pages, they are much easier to read and understand. These utilities were chosen because you will work with them day in and day out (for example, ls and cp), because they are powerful tools that are especially useful in shell scripts (sort, paste, and test), because they help you work with your Mac OS X system (ps, kill, sysctl, and GetFileInfo), or because they enable you to communicate with other systems (ssh, scp, and ftp). Part VI also covers several utilities that were developed by Apple for OS X—they are not found on other UNIX systems (nidump, otool, launchctl, and plutil).
Each utility description includes complete explanations of its most useful options. The “Discussion” and “Notes” sections present tips and tricks for using the utility to full advantage. The “Examples” sections demonstrate how to use these utilities in real life, alone and together with other utilities to generate reports, summarize data, and extract information. Take a look at the “Examples” sections for awk (more than 20 pages, starting on page 609), ftp (page 738), and sort (page 837) to see how extensive these sections are.
Part VII includes the appendixes and the glossary.
Explains how to use regular expressions to take advantage of the hidden power of UNIX. Many utilities, including grep, sed, vim, and awk, accept regular expressions in place of simple strings of characters. A single regular expression can match many simple strings.
Details the steps typically used to solve the problems you may encounter with a Mac OS X/UNIX system. This appendix also includes many links to Web sites that offer documentation, useful UNIX information, mailing lists, and software.
This appendix is a brief guide to Mac OS X features and quirks that may be unfamiliar to users who have been using other UNIX or UNIX-like systems.
Defines more than 500 terms that pertain to the use of Mac OS X/UNIX.
The Index helps you quickly find the information you want.
Mark Sobell’s home page (www.sobell.com) contains downloadable listings of the longer programs from this book as well as pointers to many interesting and useful UNIX-related sites on the World Wide Web, a list of corrections to the book, answers to even-numbered exercises, and a solicitation for corrections, comments, and suggestions.
First and foremost I want to thank my editor at Prentice Hall, Mark L. Taub, who encouraged me and kept me on track. His comments and direction were invaluable. Thank you, Mark T.
A big “Thank You” to the folks who read through the drafts of the book and made comments that caused me to refocus parts of the book where things were not clear or were left out altogether: Thank you David Chisnall, computer scientist extraordinaire; Sean Fagan, Apple Computer; Paul M. Lambert, Apple Computer; Nicolas Roard; Stephen Worotynec, Engineering Services, Alias Systems; Gretchen Phillips, Independent Consultant, GP Enterprises; and Peggy Fenner.
Thanks to Molly Sharp of ContentWorks, the production manager who made sure the book came together as it was supposed to; Jill Hobbs, the copy editor who kept the various parts of the English language in their proper relative places; and Andrea Fox, the most amazing proofreader I have ever worked with. Thanks also to the folks at Prentice Hall who helped bring this book to life: Kim Silvestro, Publicist; Stephane Nakib, Marketing Manager; Julie Nahil, Full-Service Production Manager; Noreen Regina, Editorial Assistant; and everyone else who worked behind the scenes to make this book happen.
I am also indebted to Denis Howe, the editor of The Free On-Line Dictionary of Computing (FOLDOC). Dennis has graciously permitted me to use entries from his compilation. Be sure to visit the dictionary (www.foldoc.org).
Dr. Brian Kernighan and Rob Pike graciously allowed me to reprint the bundle script from their book, The UNIX Programming Environment (Prentice Hall, 1984).
Parts of A Practical Guide to UNIX® for Mac OS® X Users have grown from my UNIX and Linux books, and I want to thank the people who helped with those books.
Thank you to Lars Kellogg-Stedman, Harvard University; Jim A. Lola, Principal Systems Consultant, Privateer Systems, LLC; Eric S. Raymond, cofounder, Open Source Initiative; Scott Mann; Randall Lechlitner, Independent Computer Consultant; Jason Wertz, Computer Science Instructor, Montgomery County Community College; Justin Howell, Solano Community College; Ed Sawicki, The Accelerated Learning Center; David Mercer, Contechst; Jeffrey Bianchine, Advocate, Author, Journalist; John Kennedy; Chris Karr; Jim Dennis, Starshine Technical Services; Carsten Pfeiffer, Software Engineer and KDE Developer; Aaron Weber, Ximian; Matthew Miller, Boston University; Cristof Falk, Software Developer at CritterDesign; Scott Mann, IBM, Systems Management and Integration Professional; Steve Elgersma, Computer Science Department, Princeton University; Scott Dier, University of Minnesota; and Robert Haskins, Computer Net Works.
Thanks also to Dustin Puryear, Puryear Information Technology; Gabor Liptak, Independent Consultant; Bart Schaefer, Chief Technical Officer, iPost; Michael J. Jordan, Web Developer, Linux Online Inc.; Steven Gibson, owner of SuperAnt.com; John Viega, founder and Chief Scientist, Secure Software, Inc.; K. Rachael Treu, Internet Security Analyst, Global Crossing; Kara Pritchard, K & S Pritchard Enterprises, Inc.; Glen Wiley, Capitol One Finances; Karel Baloun, Senior Software Engineer, Looksmart, Ltd.; Matthew Whitworth; Dameon D. Welch-Abernathy, Nokia Systems; Josh Simon, Consultant; Stan Isaacs; and Dr. Eric H. Herrin II, Vice President, Herrin Software Development, Inc. And thanks to Doug Hughes, long-time system designer and administrator, who gave me a big hand with the sections on system administration, networks, the Internet, and programming.
More thanks go to consultants Lorraine Callahan and Steve Wampler; Ronald Hiller, Graburn Technology, Inc.; Charles A. Plater, Wayne State University; Bob Palowoda; Tom Bialaski, Sun Microsystems; Roger Hartmuller, TIS Labs at Network Associates; Kaowen Liu; Andy Spitzer; Rik Schneider; Jesse St. Laurent; Steve Bellenot; Ray W. Hiltbrand; Jennifer Witham; Gert-Jan Hagenaars; and Casper Dik.
A Practical Guide to UNIX® for Mac OS® X Users is based in part on two of my early UNIX books: UNIX System V: A Practical Guide and A Practical Guide to the UNIX System. Many people helped me with those books, and thanks here go to Pat Parseghian, Dr. Kathleen Hemenway, and Brian LaRose; Byron A. Jeff, Clark Atlanta University; Charles Stross; Jeff Gitlin, Lucent Technologies; Kurt Hockenbury; Maury Bach, Intel Israel Ltd.; Peter H. Salus; Rahul Dave, University of Pennsylvania; Sean Walton, Intelligent Algorithmic Solutions; Tim Segall, Computer Sciences Corporation; Behrouz Forouzan, DeAnza College; Mike Keenan, Virginia Polytechnic Institute and State University; Mike Johnson, Oregon State University; Jandelyn Plane, University of Maryland; Arnold Robbins and Sathis Menon, Georgia Institute of Technology; Cliff Shaffer, Virginia Polytechnic Institute and State University; and Steven Stepanek, California State University, Northridge, for reviewing the book.
I continue to be grateful to the many people who helped with the early editions of my UNIX books. Special thanks are due to Roger Sippl, Laura King, and Roy Harrington for introducing me to the UNIX system. My mother, Dr. Helen Sobell, provided invaluable comments on the original manuscript at several junctures. Also, thanks go to Isaac Rabinovitch, Professor Raphael Finkel, Professor Randolph Bentson, Bob Greenberg, Professor Udo Pooch, Judy Ross, Dr. Robert Veroff, Dr. Mike Denny, Joe DiMartino, Dr. John Mashey, Diane Schulz, Robert Jung, Charles Whitaker, Don Cragun, Brian Dougherty, Dr. Robert Fish, Guy Harris, Ping Liao, Gary Lindgren, Dr. Jarrett Rosenberg, Dr. Peter Smith, Bill Weber, Mike Bianchi, Scooter Morris, Clarke Echols, Oliver Grillmeyer, Dr. David Korn, Dr. Scott Weikart, and Dr. Richard Curtis.
We take responsibility for any errors and omissions in this book. If you find one or just have a comment, let us know (email@example.com) and we will fix it in the next printing. Mark Sobell’s home page (www.sobell.com) contains a list of errors and credits those who found them. It also offers copies of the longer scripts from the book and pointers to many interesting Mac OS X sites.
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Errata for this book is available at: http://www.sobell.com/OSX1/errata.html