Book Image

Linux Command Line and Shell Scripting Bible - Third Edition

By : Richard Blum, Christine Bresnahan
Book Image

Linux Command Line and Shell Scripting Bible - Third Edition

By: Richard Blum, Christine Bresnahan

Overview of this book

The Linux command line enables you to type specific shell commands directly into the system to manipulate files and query system resources. Command line statements can be combined into short programs called shell scripts, a practice increasing in popularity due to its usefulness in automation. Linux is a robust system with tremendous potential, and Linux Command Line and Shell Scripting Bible opens the door to new possibilities. Linux Command Line and Shell Scripting Bible is your essential Linux guide. It contains new functional examples that are fully updated to align with the latest Linux features. Beginning with command line fundamentals, the book moves into shell scripting and shows you the practical application of commands in automating frequently performed functions. This book is a complete guide providing detailed instruction and expert advice working within this aspect of Linux. Whether used as a tutorial or as a quick reference, this book contains information that every Linux user should know.
Table of Contents (34 chapters)
Part I: The Linux Command Line
Part II: Shell Scripting Basics
Part III: Advanced Shell Scripting
Part IV: Creating Practical Scripts
End User License Agreement

Array Variables and Functions

Chapter 6 discussed an advanced way of allowing a single variable to hold multiple values by using arrays. Using array variable values with functions is a little tricky, and there are some special considerations. This section describes a technique that allows you to do that.

Passing arrays to functions

The art of passing an array variable to a script function can be confusing. If you try to pass the array variable as a single parameter, it doesn't work:

$ cat badtest3
# trying to pass an array variable
function testit {
   echo "The parameters are: $@"
   echo "The received array is ${thisarray[*]}"
myarray=(1 2 3 4 5)
echo "The original array is: ${myarray[*]}"
testit $myarray
$ ./badtest3
The original array is: 1 2 3 4 5
The parameters are: 1
The received array is 1

If you try using the array variable as a function parameter, the function only picks up the first value of the array variable...