Difference between revisions of "BASH/C2/More-on-Arrays/English-timed"
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Revision as of 10:26, 16 July 2015
Title of script: More on Arrays in BASH Shell Scripting
Author: Lavitha Pereira
Keywords: video tutorial, Bash shell, Array
| Time | Narration |
|---|---|
| 00:02 | Welcome to the spoken tutorial on More on Arrays in BASH. |
| 00:07 | In this tutorial, we will learn to: |
| 00:10 | * Extract an element from an array |
| 00:13 | * Replace an element in an array |
| 00:16 | * Add an element to an array and |
| 00:19 | * Remove an element from an array. |
| 00:22 | To follow this tutorial, you should be familiar with the Linux Operating System. |
| 00:28 | If not, for relevant tutorials, please visit our website which is as shown. |
| 00:34 | For this tutorial, I am using
|
| 00:41 | * GNU Bash version 4.1.10 |
| 00:45 | GNU Bash version 4 or above is recommended for practice. |
| 00:50 | Let us see how to extract an element from an array. |
| 00:55 | The elements in an array can be extracted from any position. |
| 01:00 | Here, position is the index number. |
| 01:04 | Note that index number always starts from zero. |
| 01:09 | The syntax is as follows: |
| 01:12 | ArrayName within square bracket "At" sign colon position colon Number of elements to be extracted from the position mentioned. |
| 01:25 | Let us understand with the help of an example. |
| 01:29 | Open the terminal by pressing Ctrl+Alt and T keys simultaneously on your keyboard. |
| 01:37 | Type: gedit space array2.sh space & (ampersand sign). Press Enter. |
| 01:47 | Now type the code as shown here, in your "array2.sh" file. |
| 01:54 | Let me explain the program. |
| 01:56 | This is the Shebang line. |
| 01:59 | This "declare" command declares an array named Linux with elements- |
| 02:06 | * "Debian" |
| 02:07 | * "Redhat" |
| 02:08 | * "Ubuntu" and |
| 02:09 | * "Fedora". |
| 02:11 | This "echo" command will print the list of all the elements in the array. |
| 02:16 | The next "echo" command will print the extracted elements. |
| 02:21 | The command ${Linux[@]:1:2} will print two elements starting from index 'one' which is "Redhat". |
| 02:34 | Now switch to the Terminal. |
| 02:36 | First, let's make the file executable by typing chmod space plus x space array2.sh. Press Enter. |
| 02:50 | Type: dot slash array2.sh press Enter. |
| 02:56 | We get the output - "Original elements in an array Linux: Debian Redhat Ubuntu Fedora". |
| 03:06 | "The two elements starting from index one(Redhat): Redhat Ubuntu". |
| 03:12 | Let us switch back to the slides. |
| 03:15 | We will see how to replace an element in an array . |
| 03:19 | An existing element in an array can be replaced using the following syntax. |
| 03:25 | ArrayName within square brackets 'n' equals to within single quote NewWord. |
| 03:34 | Here 'n' is the index number or element number. |
| 03:38 | Come back to our text editor. |
| 03:41 | Linux[2]='Mandriva' . |
| 03:45 | This command will replace the third element "Ubuntu" with "Mandriva". |
| 03:51 | This echo command will display all elements of array Linux after replacement. |
| 03:58 | Come back to our Terminal. |
| 04:01 | Let's execute again. |
| 04:04 | This displays- "All elements after replacement : Debian Redhat Mandriva Fedora" . |
| 04:12 | Now, switch to the slides. |
| 04:14 | We will see how to add an element to an array. |
| 04:18 | ArrayName equal to opening round bracket within double quotes dollar sign opening curly bracket ArrayName opening square bracket "At" sign closing square bracket closing curly bracket
space within double quotes New_Word_1 space within double quotes New_Word_2 and closing round bracket. |
| 04:45 | Let us understand this with the help of one example. |
| 04:50 | Switch to the code file. |
| 04:52 | The highlighted command will append a new element "Suse" to the array Linux. |
| 04:59 | Then we will echo all the elements after appending "Suse". |
| 05:05 | Switch to the terminal. |
| 05:07 | Let me clear the prompt. |
| 05:09 | We will execute the program again. |
| 05:12 | The output is displayed: All elements after appending Suse : Debian Redhat Mandriva Fedora and Suse. |
| 05:22 | Now, come back to our slides. |
| 05:24 | We will see how to remove an element from an array. |
| 05:29 | An element can be removed from an array by using the following syntax - |
| 05:35 | unset space ArrayName opening square bracket index number closing square bracket. |
| 05:44 | Let us switch to the code file. |
| 05:46 | Here, we are using the unset command. |
| 05:50 | And we will remove the third element Mandriva from the array Linux. |
| 05:56 | Then we will echo all the elements again after the removal of Mandriva. |
| 06:02 | Now switch to the terminal. |
| 06:04 | We will execute the program. |
| 06:07 | Here is the list of elements after removing Mandriva. |
| 06:12 | Debian Redhat Fedora and Suse |
| 06:16 | This brings us to the end of this tutorial. |
| 06:19 | Come back to our slides. |
| 06:21 | Let us summarize. |
| 06:23 | In this tutorial, we learned to: |
| 06:25 | * Extract an element from an array |
| 06:28 | * Replace an element in an array |
| 06:30 | * Add element to an array and |
| 06:32 | * Remove element from an array. |
| 06:36 | As an assignment- |
| 06:37 | # Declare an array names of length 7 and perform following operations. |
| 06:44 | * Extract three elements, starting from index two. |
| 06:48 | * Replace third element with Debian and display. |
| 06:55 | Append any new name at the end of array. |
| 06:58 | Watch the video available at the link shown below. |
| 07:01 | It summarizes the Spoken Tutorial project. |
| 07:04 | If you do not have good bandwidth, you can download and watch it. |
| 07:09 | The Spoken Tutorial Project team: |
| 07:12 | * Conducts workshops using spoken tutorials. |
| 07:15 | * Gives certificates to those who pass an online test. |
| 07:19 | For more details, please write to contact@spoken-tutorial.org |
| 07:27 | Spoken Tutorial Project is a part of the Talk to a Teacher project. |
| 07:31 | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
| 07:38 | More information on this mission is available at the link shown below. |
| 07:44 | The script has been contributed by FOSSEE and spoken-tutorial teams. |
| 07:50 | This is Ashwini Patil from IIT Bombay, signing off. |
| 07:55 | Thank you for joining. |
