Linux Command Line and Shell Scripting Bible

Introduction xxxi Part I: The Linux Command Line 1 Chapter 1: Starting with Linux Shells 3 What Is Linux? 3 Looking into the Linux kernel 4 The GNU utilities 9 The Linux desktop environment 11 Linux Distributions 17 Summary 21 Chapter 2: Getting to the Shell 23 Reaching the Command Line 23 Accessing CLI via a Linux Console Terminal 25 Accessing CLI via Graphical Terminal Emulation 28 Using the GNOME Terminal Emulator 29 Using the Konsole Terminal Emulator 35 Using the xterm Terminal Emulator 41 Summary 44 Chapter 3: Basic bash Shell Commands 47 Starting the Shell 47 Using the Shell Prompt 48 Interacting with the bash Manual 49 Navigating the Filesystem 52 Listing Files and Directories 59 Handling Files 64 Managing Directories 73 Viewing File Contents 77 Viewing parts of a file 81 Summary 83 Chapter 4: More bash Shell Commands 85 Monitoring Programs 85 Monitoring Disk Space 96 Working with Data Files 102 Summary 111 Chapter 5: Understanding the Shell 113 Exploring Shell Types 113 Exploring Parent and Child Shell Relationships 115 Understanding Shell Built-In Commands 125 Summary 132 Chapter 6: Using Linux Environment Variables 135 Exploring Environment Variables 135 Setting User-Defined Variables 138 Removing Environment Variables 142 Uncovering Default Shell Environment Variables 143 Setting the PATH Environment Variable 148 Locating System Environment Variables 150 Learning about Variable Arrays 158 Summary 159 Chapter 7: Understanding Linux File Permissions 161 Linux Security 161 Using Linux Groups 172 Decoding File Permissions 175 Changing Security Settings 179 Sharing Files 182 Summary 184 Chapter 8: Managing Filesystems 187 Exploring Linux Filesystems 187 Understanding the copy-on-write filesystems 192 Working with Filesystems 192 Managing Logical Volumes 200 Summary 210 Chapter 9: Installing Software 211 Package Management Primer 211 The Debian-Based Systems 212 The Red Hat-Based Systems 221 Installing from Source Code 228 Summary 232 Chapter 10: Working with Editors 233 Visiting the vim Editor 233 Navigating the nano Editor 240 Exploring the emacs Editor 242 Exploring the KDE Family of Editors 251 Exploring the GNOME Editor 260 Summary 265 Part II: Shell Scripting Basics 267 Chapter 11: Basic Script Building 269 Using Multiple Commands 269 Creating a Script File 270 Displaying Messages 272 Using Variables 274 Redirecting Input and Output 279 Pipes 281 Performing Math 285 Exiting the Script 292 Summary 295 Chapter 12: Using Structured Commands 297 Working with the if-then Statement 297 Exploring the if-then-else Statement 300 Nesting ifs 301 Trying the test Command 304 Considering Compound Testing 324 Working with Advanced if-then Features 325 Considering the case Command 327 Summary 329 Chapter 13: More Structured Commands 331 The for Command 331 The C-Style for Command 341 The while Command 343 The until Command 346 Nesting Loops 347 Looping on File Data 350 Controlling the Loop 351 Processing the Output of a Loop 358 Practical Examples 359 Summary 362 Chapter 14: Handling User Input 365 Passing Parameters 365 Using Special Parameter Variables 371 Being Shifty 375 Working with Options 376 Standardizing Options 387 Getting User Input 388 Summary 392 Chapter 15: Presenting Data 395 Understanding Input and Output 395 Redirecting Output in Scripts 400 Redirecting Input in Scripts 402 Creating Your Own Redirection 403 Listing Open File Descriptors 408 Suppressing Command Output 410 Using Temporary Files 411 Logging Messages 414 Practical Example 416 Summary 418 Chapter 16: Script Control 419 Handling Signals 419 Running Scripts in Background Mode 427 Running Scripts without a Hang-Up 430 Controlling the Job 432 Being Nice 436 Running Like Clockwork 438 Summary 446 Part III: Advanced Shell Scripting 447 Chapter 17: Creating Functions 449 Basic Script Functions 449 Returning a Value 453 Using Variables in Functions 456 Array Variables and Functions 461 Function Recursion 464 Following a Practical Example 470 Summary 474 Chapter 18: Writing Scripts for Graphical Desktops 477 Creating Text Menus 477 Doing Windows 484 Getting Graphic 496 Summary 504 Chapter 19: Introducing sed and gawk 505 Manipulating Text 505 Getting to know the sed editor 505 Getting to know the gawk program 509 Commanding at the sed Editor Basics 516 Using addresses 518 Deleting lines 521 Inserting and appending text 523 Changing lines 525 Transforming characters 527 Printing revisited 527 Using files with sed 530 Summary 533 Chapter 20: Regular Expressions 535 What Are Regular Expressions? 535 Defining BRE Patterns 537 Plain text 537 Special characters 539 Anchor characters 540 Extended Regular Expressions 549 Regular Expressions in Action 554 Summary 560 Chapter 21: Advanced sed 561 Looking at Multiline Commands 561 Holding Space 567 Negating a Command 569 Changing the Flow 572 Replacing via a Pattern 575 Placing sed Commands in Scripts 577 Creating sed Utilities 579 Summary 588 Chapter 22: Advanced gawk 591 Using Variables 591 Working with Arrays 600 Using Patterns 602 Structured Commands 605 Formatted Printing 610 Built-In Functions 613 User-Defined Functions 617 Working through a Practical Example 620 Summary 621 Chapter 23: Working with Alternative Shells 623 What Is the dash Shell? 623 The dash Shell Features 624 The dash command line parameters 624 The dash environment variables 625 The dash built-in commands 628 Scripting in dash 629 Creating dash scripts 629 Things that don't work 629 The zsh Shell 632 Parts of the zsh Shell 632 Shell options 632 Built-in commands 633 Scripting with zsh 638 Mathematical operations 639 Structured commands 640 Functions 641 Summary 642 Part IV: Creating Practical Scripts 643 Chapter 24 Writing Simple Script Utilities 645 Performing Archives 645 Archiving data files 645 Managing User Accounts 656 Obtaining the required functions 657 Creating the script 665 Running the script 671 Monitoring Disk Space 673 Obtaining the required functions 673 Creating the script 676 Running the script 677 Summary 678 Chapter 25: Producing Scripts for Database, Web, and E-Mail 681 Using a MySQL Database 681 Using MySQL 682 Using the database in your scripts 692 Using the Web 697 Installing Lynx 698 The lynx command line 699 The Lynx configuration file 700 Capturing data from Lynx 701 Using E-Mail 704 Summary 708 Chapter 26: Creating Fun Little Shell Scripts 709 Sending a Message 709 Understanding the required functions 709 Creating the script 712 Obtaining a Quote 720 Understanding the required functions 720 Creating the script 724 Generating an Excuse 731 Understanding the required functions 732 Creating the script 735 Summary 737 Appendix A: Quick Guide to bash Commands 739 Appendix B: Quick Guide to sed and gawk 751 Index 763