BASH/C2/Array-Operations-in-BASH/English

Title of script: Array Operations In BASH

Author: Lavitha Pereira

Keywords: Video tutorial, Bash shell, Array

Visual Cue	Narration
Display Slide 1	Welcome to the spoken tutorial on Array operations in BASH
Display Slide 2 Learning Objectives	In this tutorial, we will learn how to Declare an Array and assign value to it. Initialize an Array during declaration
Display Slide 3 Learning Objectives (contd.)	* To find length of an Array and its nth element To print an Array
Display Slide 4 Prerequisites spoken-tutorial.org	To follow this tutorial, You should be familiar with the Linux Operating System. If not, for relevant tutorials please visit spoken hyphen tutorial dot org.
Display Slide 5 System Requirements	For this tutorial I am using Ubuntu Linux 12.04 OS and GNU Bash version 4.1.10 GNU Bash version 4 or above is recommended to practise this tutorial.
Display Slide 6 Array Definition	Let us start with the definition of an Array and its characteristics. An Array is a variable with multiple values. The values can be of same or different types
Display Slide 7 Array Charactristics	* There is no maximum limit for the size of an array Array members need not be consecutive Array index always starts with zero
Display Slide 8 Declare and assign values to an Array Syntax: declare -a arrayname	We will now see how to declare and assign a value to an Array. The syntax to declare an Array is - declare space hyphen `a` space arrayname
	“declare” keyword is used to declare an Array. It is a built-in command in Bash.
Display slide 8 Syntax: Name[index]='value'	The syntax to assign a value to an Array is- Name opening square bracket index closing square bracket equal to within single quotes value.
=== Display Slide 9 === Initialize an Array during declaration	Now let see how to initialize an Array during declaration. Arrays can be declared and initialized at the same time. Each element in the list is separated by a space and is within parentheses.
=== Display Slide 10 === Initialize an Array during declaration Syntax: declare -a arrayname=('element1' 'element2' 'element3')	The syntax is as shown declare space hyphen `a` space arrayname equal-to opening round bracket within single quotes 'element1' space 'element2' space 'element3' closing round bracket.
	Let us try an example.
Press Ctrl+Alt+T	Open the terminal by pressingCtrl+Alt+T keys simultaneously.
On Terminal >>Type gedit array.sh	Type: gedit space array.sh on the terminal. Now type the code as shown here into your array.sh file.
Highlight declare -a Linux=('Debian' 'Redhat' 'Ubuntu' 'Fedora')	This line declares an Array named Linux with elements - Debian, Redhat, Ubuntu and Fedora
	Here hyphen `a` is a flag. It allows us to read and assign values to an Array.
	Let us switch back to the slides.
=== Display Slide === Length of an Array and of its nth element. ${#arrayname[@]}	The length of an Array can be obtained by this code: Dollar symbol opening curly bracket hash arrayname opening square bracket At sign closing square bracket closing curly bracket
=== Display Slide (contd.) === ${#arrayname[n]}	The length of the nth element can be obtained by this code: Dollar symbol opening curly bracket hash arrayname opening square bracket index number `n` closing square bracket closing curly bracket. Here n is the element number, whose length is to be found.
=== Display Slide === Print the whole Array Syntax: ${arrayname[@]}	All the elements of the Array can be printed using this syntax. Dollar sign opening curlybracket Arrayname opening square bracket `At sign` closing square bracket closing curly bracket.
	Come back to the text editor.
[Highlight] echo -e "Total number elements in an array Linux: ${#Linux[@]} \n"	This line will display total number of elements in the Array Linux. hyphen `e` enables interpretation of backslash escapes. We have included this as we have backslash `n` at the end of the line.
echo -e "The elements of array Linux are: ${Linux[@]} \n"	Next line displays all the elements of the Array Linux.
echo -e "Third element in array Linux is: ${Linux[2]} \n"	This line displays the 3rd element of the Array Linux. Please note that an Array always starts with index zero.
echo -e "Length of third element is: ${#Linux[2]} \n"	Lastly, this line displays the number of characters present in the 3rd element.
Switch to Terminal>>Type chmod +x array.sh>> Press Enter>>	Switch to the Terminal. Let's first make the file executable by typingchmod space plus x space array.sh Press Enter.
Type ./array>> Press Enter	Now execute by typing dot slash array.sh Press Enter.
Output: [Highlight] Length of the Array Linux is: 4	The number of elements or the length of the Array `Linux`is four.
Output: [Highlight] The elements of Array Linux are: Debian Redhat Ubuntu Fedora	The elements of the Array Linux are Debian, Redhat, Ubuntu, Fedora
Output: [Highlight] Third Element in Array Linux is: Ubuntu	The 3rd element of Array Linux is Ubuntu
Output: [Highlight] Length of Third Element is: 6	And the number of characters in the third element is six, as expected. <pause>
	Let us summarize. Come back to our slides.
Display slide Summary	In this tutorial we learnt, Declare and assign values to an Array Initialize an Array during declaration How to find length of an Array and length of its nth element and To print whole Array
Display Slide 9 Assignment	As an assignment. Declare an array names of length 7 and find: the total number of elements print all the elements print the 5th element
	Watch the video available at the link shown below It summarises the Spoken Tutorial project If you do not have good bandwidth, you can download and watch it
Display Slide Spoken Tutorial Workshops	The Spoken Tutorial Project Team Conducts workshops using spoken tutorials Gives certificates to those who pass an online test For more details, please write to contact@spoken-tutorial.org
Display Slide Acknowledgement	Spoken Tutorial Project is a part of the Talk to a Teacher project It is supported by the National Mission on Education through ICT, MHRD, Government of India More information on this Mission is available at: http://spoken-tutorial.org\NMEICT-Intro
Display Slide	The script has been contributed by FOSSEE and spoken-tutorial team. This is Ashwini from IIT Bombay. Thank you for joining.

Contributors and Content Editors

Ashwini