Difference between revisions of "BASH/C2/Arithmetic-Comparison/English-timed"

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'''Title of script:''' '''Arithmetic comparison in BASH'''
 
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'''Author:''' Ashwini Patil
 
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'''Keywords: video tutorial, Bash shell, -eq, -ne, -gt, -ge, -lt, -le'''
 
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{| border=1  
 
{| border=1  
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!Time  
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|'''Time'''
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!Narration  
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|'''Narration'''
  
 
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|-
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|-
 
|-
 
|  00:09
 
|  00:09
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| * '''equal to'''
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| '''equal to (-eq)''' '''not equal to (-ne)'''
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+
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|-
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|  00:10
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| * '''not equal to'''
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|-
 
|-
 
|  00:12
 
|  00:12
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|* '''less than'''
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| '''less than (-lt)''''''less than equal to (-le)'''
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|-
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|  00:13
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|* '''less than equal to'''
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|-
 
|-
 
|  00:15
 
|  00:15
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|* '''greater than''' and
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| '''greater than (-gt)''' and'''greater than equal to (-ge)''' '''commands'''.
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|-
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|  00:16
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|* '''greater than equal to''' '''commands'''.
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| 00:26  
 
| 00:26  
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| * '''Ubuntu Linux 12.04''' Operating System   
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| '''Ubuntu Linux 12.04''' Operating System   
  
 
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| 00:30  
 
| 00:30  
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| *'''GNU BASH''' version '''4.1.10'''
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| '''GNU BASH''' version '''4.1.10'''
  
 
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|-
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|-
 
|  02:00  
 
|  02:00  
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| So, this '''statement''' counts the words in a given file.
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| So, this statement counts the words in a given file.
  
 
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|  02:16   
 
|  02:16   
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| If the condition is '''True,''' we will print a message '''“File has zero words”.'''
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| If the condition is '''True,''' we will print a message '''"File has zero words”.'''
  
 
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|-
 
|  02:22   
 
|  02:22   
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| '''fi''' is the end of first '''if''' condition.
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| '''"fi"''' is the end of first '''if''' condition.
  
 
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|  02:40
 
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| '''$ (dollar) x''' will give the word count.
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| '''$x (dollar x)''' will give the word count.
  
 
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|  02:48
 
|  02:48
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| Let us '''execute''' our '''program.'''
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| Let us '''execute''' our program.
  
 
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| 03:26  
 
| 03:26  
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| '''Enter filename: ''' is displayed.
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| '''"Enter filename:" ''' is displayed.
  
 
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| 03:28  
 
| 03:28  
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| Type:
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| Type: '''list.txt'''
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'''list.txt'''
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| 03:31  
 
| 03:31  
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| The output is displayed as: '''list.txt has 3 words'''.
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| The output is displayed as: '''"list.txt has 3 words"'''.
  
 
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| 03:46  
 
| 03:46  
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|  Please open a file in your '''editor''' and name it as '''example2.sh'''
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|  Please open a file in your '''editor''' and name it as "example2.sh".
  
 
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|-
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|   03:52
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|03:52
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| Now type the code as shown here in your ''' example2.sh''' file.
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|Now type the code as shown here, in your "example2.sh" file.
  
 
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| 03:58  
 
| 03:58  
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| Let me explain the code.
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|Let me explain the code.
  
 
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|-
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| 04:00
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|04:00
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| This program will check whether the word count is-  
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|This program will check whether the word count is-  
  
 
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|  04:04
 
|  04:04
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| * greater or less than one
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| greater or less than one
  
 
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| 04:07
 
| 04:07
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| * Between one and hundred or above hundred.
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| Between one and hundred or above hundred.
  
 
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|  04:37
 
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| '''fi''' ends the '''if condition.'''
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| '''"fi"''' ends the '''if condition.'''
  
 
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|  04:45
 
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| First, the '''- (hyphen) gt''' command checks whether word count is greater than one.
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| First, '''- (hyphen) gt''' command checks whether word count is greater than one.
  
 
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|  04:51
 
|  04:51
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| If yes, then this '''echo statement ''' will be executed.
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| If 'yes' then this '''echo statement ''' will be executed.
  
 
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| 05:01
 
| 05:01
 
| Here, in this '''if''':
 
| Here, in this '''if''':
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* '''- (hyphen) ge '''command checks whether word count is greater than or equal to one and
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'''- (hyphen) ge '''command checks whether word count is greater than or equal to one and
  
 
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|-
 
| 05:09
 
| 05:09
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|* '''- (hyphen) le '''command checks whether word count is less than or equal to hundred.
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| '''- (hyphen) le '''command checks whether word count is less than or equal to hundred.
  
 
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| 05:21
 
| 05:21
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| '''Number of characters ranges between 1 and 100.'''
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| '''"Number of characters ranges between 1 and 100".'''
  
 
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|-
 
| 05:25
 
| 05:25
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| Please note that both '''conditions''' should be true to satisfy the entire '''if condition'''.  
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| Please note that both '''conditions''' should be '''True''' to satisfy the entire '''if condition'''.  
  
 
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| 05:39
 
| 05:39
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| '''fi''' is the end of this '''if statement'''.
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| '''"fi"''' is the end of this '''if statement'''.
  
 
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|  05:53   
 
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| If the condition is satisfied, we print '''Number of characters is above hundred.'''
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| If the condition is satisfied, we print '''"Number of characters is above hundred".'''
  
 
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|  06:00   
 
|  06:00   
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| '''fi '''is the end of '''if statement.'''
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| '''"fi" '''is the end of '''if statement.'''
  
 
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|  06:25  
 
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|  The '''output''' is displayed as '''list.txt has more than one character'''.
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|  The '''output''' is displayed as '''"list.txt has more than one character"'''.
  
 
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| 06:31  
 
| 06:31  
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| '''Number of characters ranges between one and hundred'''.
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| '''"Number of characters ranges between one and hundred"'''.
  
 
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|-
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| 06:51
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|06:51
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| In this tutorial we learnt:
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|In this tutorial we learnt:
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* '''equal to'''
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'''equal to'''
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* '''not equal to'''
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'''not equal to'''
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* '''less than'''
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'''less than'''
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* '''less than equal to'''
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'''less than equal to'''
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* '''greater than''' and
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'''greater than''' and
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* '''greater than equal to''' '''commands'''.
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'''greater than equal to''' '''commands'''.
  
 
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|-
 
|  07:03     
 
|  07:03     
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|  As an assignment, write a program to demonstrate the use of '''not equal to''' operator.
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|  As an assignment, write a program to demonstrate the use of '''not equal to''' '''operator'''.
  
 
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|-
 
|  07:09     
 
|  07:09     
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| Hint: '''- (hyphen) ne'''
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| Hint: '''- (hyphen) ne'''.
  
 
|-
 
|-

Latest revision as of 16:09, 23 March 2017

Time Narration
00:01 Welcome to the spoken tutorial on Arithmetic Comparison in BASH.
00:07 In this tutorial, we will learn:
00:09 equal to (-eq) not equal to (-ne)
00:12 less than (-lt)'less than equal to (-le)'
00:15 greater than (-gt) andgreater than equal to (-ge) commands.
00:19 We will do this with the help of some examples.
00:23 For this tutorial, I am using:
00:26 Ubuntu Linux 12.04 Operating System
00:30 GNU BASH version 4.1.10
00:34 GNU Bash version 4 or above is recommended for practice.
00:39 I already have a working example of arithmetic operators.
00:43 Let me switch to it.
00:45 I have named the file example1.sh.
00:50 Open a file in any editor of your choice and type the code as shown.
00:56 You must be familiar how to do so, by now.
01:00 In this program, we will check whether a given file is empty or not.
01:06 Let me explain the code.
01:08 This is the shebang line.
01:10 First of all, “Enter filename” will be printed on the console.
01:15 read command reads one line of data from the standard input.
01:20 This command is enclosed within backticks.
01:24 Backtick has a very special meaning.
01:27 Everything you type between backtick is evaluated.
01:32 cat command will display the content of the file.
01:37 wc will print newline, word and byte counts for each file.
01:43 - (hyphen) w will print the word count.
01:47 What will happen is -
01:49 First the cat command will read the file.
01:53 This is the input file
01:55 which is then piped or sent to the wc command.
02:00 So, this statement counts the words in a given file.
02:05 The output is stored in variable x.
02:08 This is the if statement.
02:10 - (hyphen) eq command checks whether word count is equal to zero.
02:16 If the condition is True, we will print a message "File has zero words”.
02:22 "fi" is the end of first if condition.
02:26 Here is another if condition.
02:28 Here, - (hyphen) ne command checks whether word count is not equal to zero.
02:35 If the condition is True, we print “File has so-and-so words”.
02:40 $x (dollar x) will give the word count.
02:43 This is the end of 2nd if condition.
02:46 Save your program file.
02:48 Let us execute our program.
02:51 Open the terminal.
02:53 First let's create a file list.txt.
02:57 Type: touch list.txt.
03:01 Now, let's add a line in the file.
03:04 Type:

echo within double quotes “How are you” after the double quotes greater than sign list.txt.

03:13 Now let's make our script executable.
03:16 Type:

chmod plus x example1 dot sh

03:21 Now, type: dot slash example1.sh
03:26 "Enter filename:" is displayed.
03:28 Type: list.txt
03:31 The output is displayed as: "list.txt has 3 words".
03:36 Now let's learn about another set of operators.
03:40 Let me switch to another file.
03:43 This is example2.sh .
03:46 Please open a file in your editor and name it as "example2.sh".
03:52 Now type the code as shown here, in your "example2.sh" file.
03:58 Let me explain the code.
04:00 This program will check whether the word count is-
04:04 greater or less than one
04:07 Between one and hundred or above hundred.
04:11 We have our shebang line here.
04:14 read statement takes input as filename from the user.
04:19 Here, - (hyphen) c command is used to print the byte counts.
04:24 In the if statement, - (hyphen) lt command checks whether word count is less than one.
04:31 If the condition is True then we print “No characters present in the file”.
04:37 "fi" ends the if condition.
04:40 The next if statement contains a nested if statement.
04:45 First, - (hyphen) gt command checks whether word count is greater than one.
04:51 If 'yes' then this echo statement will be executed.
04:56 There are multiple conditions within this if statement.
05:01 Here, in this if:

- (hyphen) ge command checks whether word count is greater than or equal to one and

05:09 - (hyphen) le command checks whether word count is less than or equal to hundred.
05:17 If both the conditions are satisfied then it prints:
05:21 "Number of characters ranges between 1 and 100".
05:25 Please note that both conditions should be True to satisfy the entire if condition.
05:33 This is because we have included ampersand in-between both the conditions.
05:39 "fi" is the end of this if statement.
05:43 Then the next if statement will be evaluated.
05:47 - (hyphen) gt command checks whether word count is greater than hundred.
05:53 If the condition is satisfied, we print "Number of characters is above hundred".
06:00 "fi" is the end of if statement.
06:04 Here we end the 2nd if statement.
06:07 Now come back to our terminal.
06:10 Let us execute the program.
06:13 chmod plus x example2 dot sh
06:18 dot slash example2 dot sh
06:22 Type list.txt .
06:25 The output is displayed as "list.txt has more than one character".
06:31 "Number of characters ranges between one and hundred".
06:36 Now, add or remove characters to the list.txt file.
06:40 Then observe which if statement gets executed.
06:46 This brings us to the end of this tutorial.
06:49 Let us summarize.
06:51 In this tutorial we learnt:

equal to not equal to less than less than equal to greater than and greater than equal to commands.

07:03 As an assignment, write a program to demonstrate the use of not equal to operator.
07:09 Hint: - (hyphen) ne.
07:12 Watch the video available at the link shown below.
07:15 It summarizes the Spoken-Tutorial project.
07:18 If you do not have good bandwidth, you can download and watch it.
07:23 The Spoken Tutorial Project team:
07:25 Conducts workshops using spoken tutorials.
07:28 Gives certificates to those who pass an online test.
07:32 For more details, please write to contact@spoken-tutorial.org
07:40 Spoken Tutorial project is a part of the Talk to a Teacher project.
07:43 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
07:51 More information on this mission is available at the link shown below.
07:56 The script has been contributed by FOSSEE and spoken-tutorial team.
08:02 This is Ashwini Patil from IIT Bombay, signing off.
08:06 Thank you for joining.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Ranjana, Sandhya.np14

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