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Arrays in Linux Shell Scripting

Arrays & Their Types in Linux:


In Linux shell scripting, an array is used when we need to store more than one value in a single variable. An array is a way of storing data in an ordered manner, where we can store multiple values together in one variable. Arrays are used to make various tasks easier and more effective, especially when we need to manage multiple data points. There are two types of arrays in the Linux shell: one-dimensional and multi-dimensional arrays.

Definition of an Array: An array is a type of data structure in which multiple values of the same type can be stored. The specialty of arrays in shell scripting is that their indices start from 0.

Declaring an Array: An array can be declared using the following syntax: `array_name=(element1 element2 element3 ...)`. For example: `fruits=("apple" "banana" "cherry")`.

Types of Arrays:

One-dimensional Array: This is the most common type of array in which there are multiple elements of the same type, and each element has an index by which we can access it. Elements can be accessed using `${array_name[index]}` and modified using `array_name[index]=value`.

Multi-dimensional Array: Although shell scripting does not directly support multi-dimensional arrays, we can implement them by using arrays within arrays. This allows us to store more complex data structures. Accessing and modifying elements in a multi-dimensional array is a bit more complex.

Features and Uses of Arrays: Arrays are used for managing large amounts of data, providing quick access to data through indexing, and creating reusable data structures.

Advantages and Disadvantages of Arrays:
Advantages: Efficient for storing multiple values, easy access to elements, and provides a structured way to manage data.
Disadvantages: Fixed size (difficult to change once set), limited to a single data type, and large arrays can consume a lot of memory.

In this Chapter

Arrays in Linux Shell Scripting
Distributed System in Operating System
Real-Time System in Operating System
System Calls in Operating System
System Programs in Operating System
Structure of an Operating System
Layered Design of an Operating System Structure
UNIX in Operating System
Virtual Machine in Operating System
Kernel-Based Operating System
Process Concept in Operating System
Interacting Processes in Operating System
Threads in Operating System
Fundamentals of Scheduling in Operating System
Scheduling Criteria in Operating System
Long, Medium, and Short-Term Scheduling
Scheduling Algorithms in Operating System
Structure of a Concurrent System
Critical Region in Operating System
Critical Section in Operating System
Inter-process Communication (IPC) in Operating System
Monitors in Operating System
Semaphores in Operating System
Semaphore Implementation & Uses in Operating System
Logical and Physical Address in Operating System
Swapping in Operating System
Contiguous Allocation in Operating System
Segmentation in Operating System
Paging in Operating System
Virtual Memory using Segmentation in Operating System
Interprocess Communication Protocol in Operating System
Network Operating System
Design Issues in Distributed File System
Network Structure in Operating System
Structure of a Distributed System
File System and Coordination in Operating System
History of Linux in Operating System
Linux Commands
Programmer Interface & File Manipulation in Linux
Process Control in Linux
Kernel & Signals in Linux
File System in Linux
Blocks and Inodes in Linux
System Editors in Linux
Character Transliteration in Linux
The `ed` Line Editor in Linux
The `vi` Editor and Its Commands
Shell Scripting in Linux
Looping & Decision Making in Linux Shell Scripting
Variables & File Name Expansion in Linux
Subprograms (Functions) in Linux Shell Scripting
C Interface with Linux
Simple Shell Programs in Linux
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