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

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Title of script: Array Operations In BASH

Author: Lavitha Pereira

Keywords: Video tutorial, Bash shell, Array


Time Narration
00:01 Welcome to the spoken tutorial on Array operations in BASH.
00:05 In this tutorial, we will learn how to:
  • Declare an Array and assign value to it.
00:12 * Initialize an Array during declaration.
00:15 * To find length of an Array and its n'th element.
00:20 * To print an Array.
00:22 To follow this tutorial, You should be familiar with Linux Operating System.
00:27 For relevant tutorials, please visit: spoken hyphen tutorial dot org.
00:33 For this tutorial, I am using:
00:37 * Ubuntu Linux 12.04 OS
00:41 * GNU Bash version 4.1.10
00:45 GNU Bash version 4 or above is recommended for practice.
00:50 Let us start with the definition of an Array and its characteristics.
00:55 * An Array is a variable with multiple values.
01:01 * The values can be of same or different types.
01:04 * There is no maximum limit for the size of an array.
01:08 * Array members need not be consecutive.
01:12 * Array index always starts with zero.
01:16 We will now see how to declare and assign a value to an Array.
01:21 The syntax to declare an Array is-
01:24 declare hyphen `a` arrayname
01:28 “declare” keyword is used to declare an Array.
01:31 It is a built-in command in Bash.
01:35 The syntax to assign a value to an Array is-
01:38 Name within square brackets index equals to within single quotes value.
01:46 Now, let see how to initialize an Array during declaration.
01:51 * Array can be declared and initialized at the same time.
01:56 * Elements Should be separated by a space .
02:00 Each element should be within parentheses.
02:03 The syntax is declare hyphen `a` arrayname equal to within round brackets within single quotes 'element1' , 'element2' and element3 .
02:19 Let us try an example.
02:21 Open the terminal by pressing Ctrl+Alt and T keys simultaneously.
02:28 Now Type: gedit space array.sh space &
02:36 We use the ampersand to free up the prompt. Press Enter.
02:41 Type the code as shown here, in your array.sh file.
02:47 This line declares an Array named Linux with elements -
  • Debian,
  • Redhat,
  • Ubuntu and
  • Fedora.
02:57 Here hyphen `a` is a flag.
03:00 It allows us to read and assign values to an Array.
03:05 Let us switch back to the slides.
03:07 The length of an Array can be obtained by this syntax:
03:12 Dollar sign opening curly bracket hash arrayname within square bracket At sign (@) and closing curly bracket.
03:22 The length of the n'th element can be obtained by this syntax:
03:28 Dollar sign opening curly bracket hash arrayname within square brackets `n` and closing curly bracket.
03:37 Here 'n' is the element number whose length is to be found.
03:42 All the elements of the Array can be printed using this syntax.
03:48 Dollar sign opening curly bracket arrayname within square brackets `At sign` and closing curly bracket.
03:57 Now come back to the text editor.
04:00 This line will display total number of elements in the Array Linux.
04:06 hyphen `e` enables interpretation of backslash escapes.
04:11 We have included this as we have backslash `n` at the end of the line.
04:18 The next line displays all the elements of the Array Linux.
04:23 This line displays the 3rd element of the Array Linux.
04:28 Please note that an Array always starts with index zero.
04:34 Lastly, this line displays the number of characters present in the 3rd element.
04:40 Now, switch to the Terminal.
04:42 Let's first make the file executable by typing chmod space plus x space array.sh. Press Enter.
04:56 Type: dot slash array .sh. Press Enter.
05:01 The output is displayed.
05:04 The number of elements or the length of the Array `Linux` is four.
05:10 The elements of the Array Linux are Debian, Redhat, Ubuntu and Fedora.
05:18 The 3rd element of Array Linux is Ubuntu.
05:22 And the number of characters in the third element is six, as expected.
05:29 This brings us to the end of this tutorial.
05:32 Let us summarize. Come back to our slides.
05:35 In this tutorial, we learnt to:
05:40 * Declare and assign values to an Array
05:43 * Initialize an Array during declaration
05:46 * To find length of an Array and its nth element and
05:51 * To print whole Array.
05:53 As an assignment-
05:55 Declare an array names of length 7 and find:
06:00 * the total number of elements
06:02 * print all the elements
06:04 * And print the 5th element.
06:06 Watch the video available at the link shown below.
06:10 It summarizes the Spoken-Tutorial project.
06:13 If you do not have good bandwidth, you can download and watch it.
06:18 The Spoken Tutorial Project team:
06:20 Conducts workshops using spoken tutorials.
06:24 Gives certificates to those who pass an online test.
06:27 For more details, please write to contact@spoken-tutorial.org.
06:35 Spoken Tutorial Project is a part of the "Talk to a Teacher" project
06:40 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
06:47 More information on this mission is available at the link shown below.
06:52 The script has been contributed by FOSSEE and spoken-tutorial teams.
06:58 This is Ashwini Patil from IIT Bombay.
07:02 Thank you for joining.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Ranjana, Sandhya.np14