Table of Contents for
Learning Linux Shell Scripting

Version ebook / Retour

Cover image for bash Cookbook, 2nd Edition Learning Linux Shell Scripting by Ganesh Sanjiv Naik Published by Packt Publishing, 2015
  1. Cover
  2. Table of Contents
  3. Learning Linux Shell Scripting
  4. Learning Linux Shell Scripting
  5. Credits
  6. About the Author
  7. Acknowledgments
  8. About the Reviewers
  9. www.PacktPub.com
  10. Preface
  11. What you need for this book
  12. Who this book is for
  13. Conventions
  14. Reader feedback
  15. Customer support
  16. 1. Getting Started and Working with Shell Scripting
  17. Tasks done by shell
  18. Working in shell
  19. Learning basic Linux commands
  20. Our first script – Hello World
  21. Compiler and interpreter – difference in process
  22. When not to use scripts
  23. Various directories
  24. Working more effectively with shell – basic commands
  25. Working with permissions
  26. Summary
  27. 2. Drilling Deep into Process Management, Job Control, and Automation
  28. Monitoring processes using ps
  29. Process management
  30. Process monitoring tools – top, iostat, and vmstat
  31. Understanding "at"
  32. Understanding "crontab"
  33. Summary
  34. 3. Using Text Processing and Filters in Your Scripts
  35. IO redirection
  36. Pattern matching with the vi editor
  37. Pattern searching using grep
  38. Summary
  39. 4. Working with Commands
  40. Command substitution
  41. Command separators
  42. Logical operators
  43. Pipes
  44. Summary
  45. 5. Exploring Expressions and Variables
  46. Working with environment variables
  47. Working with read-only variables
  48. Working with command line arguments (special variables, set and shift, getopt)
  49. Understanding getopts
  50. Understanding default parameters
  51. Working with arrays
  52. Summary
  53. 6. Neat Tricks with Shell Scripting
  54. The here document and the << operator
  55. The here string and the <<< operator
  56. File handling
  57. Debugging
  58. Summary
  59. 7. Performing Arithmetic Operations in Shell Scripts
  60. Using the let command for arithmetic
  61. Using the expr command for arithmetic
  62. Binary, octal, and hex arithmetic operations
  63. A floating-point arithmetic
  64. Summary
  65. 8. Automating Decision Making in Scripts
  66. Understanding the test command
  67. Conditional constructs – if else
  68. Switching case
  69. Implementing simple menus with select
  70. Looping with the for command
  71. Exiting from the current loop iteration with the continue command
  72. Exiting from a loop with a break
  73. Working with the do while loop
  74. Using until
  75. Piping the output of a loop to a Linux command
  76. Running loops in the background
  77. The IFS and loops
  78. Summary
  79. 9. Working with Functions
  80. Passing arguments or parameters to functions
  81. Sharing the data by many functions
  82. Declaring local variables in functions
  83. Returning information from functions
  84. Running functions in the background
  85. Creating a library of functions
  86. Summary
  87. 10. Using Advanced Functionality in Scripts
  88. Using the trap command
  89. Ignoring signals
  90. Using traps in function
  91. Running scripts or processes even if the user logs out
  92. Creating dialog boxes with the dialog utility
  93. Summary
  94. 11. System Startup and Customizing a Linux System
  95. User initialization scripts
  96. Summary
  97. 12. Pattern Matching and Regular Expressions with sed and awk
  98. sed – noninteractive stream editor
  99. Using awk
  100. Summary
  101. Index

Preface

Shell scripts are an essential part of any modern operating system, such as UNIX, Linux, Windows, and similar. The scripting language or its syntax may vary from OS to OS; but the fundamental principles remain the same. I first encountered Linux Shell scripts during the development of embedded Linux product development. Shell scripts were initializing the complete product from the basic booting procedure until users logged in and a complete operating system was initialized. Another situation was in the automation of regular activities, such as the build and release management of source codes of very complex products, where more than 10,000 files were a part of a single project. Similarly, another very common requirement comes while using the make utility, which is used to compile and build complex product source codes.

Initially, I had learned scripts to solve practical problems and customize already existing products. This book is the summary of what I have learned over the years in Linux Shell scripting during project development work, consultancy, and corporate trainings and their Q&A sessions.

In this book, you will learn about the very basics of Shell scripting to complex, customized automation. By the end of this book, you will be able to confidently use your own Shell scripts for the real-world problems out there. The idea is to be as practical as possible and give you the look and feel of what real-world scripting looks like.

This book covers bash, the GNU Bourne-Again Shell scripting. You can use the knowledge gained by reading this book for any shell of any of the UNIX flavors or distributions. You will need to take care of a few syntax changes if you are working in other shells, such as Korn, and similar. You should be able to read this book cover to cover, or you can just pick it up and read anything that you might find interesting. But perhaps most importantly, if you have a question about how to solve a particular problem or you need a hint, you will find it easy to find the right solution or something close enough to save your time and energy.

What this book covers

Chapter 1, Getting Started and Working with Shell Scripting, you will learn different ways to write and run Shell scripts. You will also learn ways to handle files and directories, and you will learn about working with permissions.

Chapter 2, Drilling Deep into Process Management, Job Control, and Automation, you will learn about basic process management. You will learn about command ps and job management using commands such as jobs, fg, bg, kill, and pkill. Later on, you will learn about process monitoring tools: top, iostat, vmstat and sar.

Chapter 3, Using Text Processing and Filters in Your Scripts, you will learn about using more, less, head, and tail commands. You will also learn text processing tools such as, cut, paste, comm, and uniq. You will learn about standard input, output, and error. Later on, you will learn about metacharacters and pattern matching using vi and grep.

Chapter 4, Working with Commands, you will learn about how shell interprets any command entered on the command line. You will also learn command substitution, separators, and pipes in detail.

Chapter 5, Exploring Expressions and Variables, you will learn about variables—environment variables. This will include how to export environment variables, set, shift, read-only variables, command-line arguments, and about creating and handling arrays.

Chapter 6, Neat Tricks with Shell Scripting, you will learn about debugging, the here operator, interactive Shell scripts for taking input from the keyboard, and file handling.

Chapter 7, Performing Arithmetic in Shell Scripts, you will learn about doing arithmetic operations in various ways, such as using declare, let, expr, and arithmetic expressions. You will also learn about representing numbers in different bases, such as hex, octal, and binary. You will learn about using the bc utility for doing floating point or fractional arithmetic.

Chapter 8, Automating Decision Making in Scripts, you will learn about using decision making in scripts working with test, if…else, and switching case. You will also use select for loop with menu. For repeating tasks such as processing lists, you will learn about using for loop, while loop and do while. You will also learn about how to control loops using break and continue statements.

Chapter 9, Working with Functions, we will understand about functions in Shell scripts. You will learn about the definition and display of functions by removing the function from the shell. You will also learn about passing arguments to functions, sharing data between functions, declaring local variables in functions, returning results from functions, and running functions in background. You will finally learn about using source and . commands. We will use these commands to use the library of functions.

Chapter 10, Using Advanced Functionality in Scripts, you will learn about using traps and signals. You will also learn about creating menus with the help of the dialog utility.

Chapter 11, System Startup and Customizing a Linux System, you will learn about Linux system startup from power on until the user login and how to customize a Linux system environment.

Chapter 12, Pattern Matching and Regular Expressions with sed and awk, you will learn about regular expressions and using sed (stream editor) and awk for text processing. You will learn about the usage of various commands and options along with a lot of examples for using sed and awk.