Difference between revisions of "BASH/C3/More-on-functions/English-timed"

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(Created page with " {|border=1 |'''Time''' |'''Narration''' |- | 00:01 |Welcome to the spoken tutorial on '''More on functions ''' |- | 00:06 | In this tutorial, we will learn |- |00:09 |To...")
 
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|Welcome to the spoken tutorial on '''More on functions '''
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|Welcome to the '''spoken tutorial''' on '''More on functions.'''
  
 
|-
 
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| 00:06
 
| 00:06
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| In this tutorial, we will learn
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| In this tutorial, we will learn:
  
 
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|00:09
 
|00:09
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|To pass an '''argument''' to a '''function '''
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|* To pass an '''argument''' to a '''function''';
  
 
|-
 
|-
 
|00:11
 
|00:11
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|Define '''local variable''' within a '''function''' and
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|* To define '''local variable''' within a '''function''' and
  
 
|-
 
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| 00:16
 
| 00:16
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|Define '''global variable''' in a '''function'''
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|* To define '''global variable''' in a '''function'''
  
 
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| 00:19
 
| 00:19
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|With the help of some examples  
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|with the help of some examples.
  
 
|-
 
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| 00:23
 
| 00:23
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| To follow this tutorial you should have knowledge of '''Shell Scripting''' in''' BASH.'''
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| To follow this tutorial, you should have knowledge of '''Shell Scripting''' in''' BASH.'''
  
 
|-
 
|-
 
| 00:28
 
| 00:28
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|If not, for relevant tutorials please visit our website which is as shown,'''(http://www.spoken-tutorial.org)'''
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|If not, for relevant tutorials, please visit our website which is as shown: '''(http://www.spoken-tutorial.org)'''
  
 
|-
 
|-
 
| 00:35
 
| 00:35
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| For this tutorial I am using''' '''
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| For this tutorial, I am using:
  
 
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|00:37
 
|00:37
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|'''Ubuntu Linux''' 12.04''' '''Operating System
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|* '''Ubuntu Linux''' 12.04 '''Operating System'''
  
 
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|00:42
 
|00:42
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|'''GNU BASH''' version 4.2
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|* '''GNU BASH''' version 4.2.
  
 
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| 00:45
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|Please note,''' GNU Bash''' '''version 4''' or above is recommended to practice this tutorial.
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|Please note,''' GNU Bash''' version 4 or above is recommended to practice this tutorial.
  
 
|-
 
|-
 
| 00:52
 
| 00:52
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| Let us first learn how to pass an '''argument''' to a '''function,''' and its usage.
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| Let us first learn how to pass an '''argument''' to a '''function''' and its usage.
  
 
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| 00:59
 
| 00:59
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| Let me open a file ''''function_(underscore) parameters.sh''''
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| Let me open a file''' 'function_(underscore) parameters.sh' '''.
  
 
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| Our '''function name''' is '''say_(underscore)welcome'''
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| Our '''function''' name is '''say_(underscore)welcome'''.
  
 
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| 01:13
 
| 01:13
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|Open curly bracket opens the '''function definition.'''
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|Open curly bracket opens the '''function''' definition.
  
 
|-  
 
|-  
 
|01:18
 
|01:18
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| '''$(Dollar)1 '''is the first '''positional parameter'''
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| '''$(Dollar)1 '''is the first '''positional parameter'''.
  
 
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| 01:22
 
| 01:22
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|'''$(Dollar)2 '''is the second '''postional parameter'''
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|'''$(Dollar)2 '''is the second '''positional parameter'''.
  
 
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|-  
 
|01:26
 
|01:26
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| Close curly bracket closes the''' function definition.'''
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| Close curly bracket closes the''' function''' definition.
  
 
|-  
 
|-  
 
|01:30
 
|01:30
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| Here, the function ''''say_welcome'''' is called with '''arguments'''.
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| Here, the function''' 'say_welcome' '''is called with '''arguments'''.
  
 
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|01:35
 
|01:35
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|The syntax is, '''function name''' i.e. '''say welcome ''' '''...'''followed by the '''arguments '''within double quotes, i.e. '''Bash''' and '''learning.'''
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|The syntax is- '''function''' name i.e. "say_welcome" followed by the '''arguments '''within double quotes, i.e. "Bash" and "learning".
  
 
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|01:49
 
|01:49
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| In a similar manner, I will call the same '''function''' with a different set of '''arguments. '''So, I have'''say_welcome space''' within double quote '''functions in''' space and within double quote '''Bash'''.
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| In a similar manner, I will '''call''' the same '''function''' with a different set of '''arguments'''. So, I have'''say_welcome''' space within double quotes '''functions in''' space and within double quotes '''Bash'''.
  
 
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| Save the file and go to the terminal.
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| '''Save''' the file and go to the '''terminal'''.
  
 
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| Type '''chmod space plus x space function underscore parameters dot sh'''
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| Type: '''chmod space plus x space function underscore parameters dot sh'''.
  
 
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| Type '''dot slash function underscore parameters dot sh'''
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| Type: '''dot slash function underscore parameters dot sh'''.
  
 
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| '''Dollar 1($1) '''was substituted by the string''' Bash''' and '''Dollar 2($2) '''with''' learning.'''
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| Dollar 1($1) was substituted by the '''string''' "Bash" and Dollar 2($2) with "learning".
  
 
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| Then again, '''Dollar 1($1) '''was substituted by''' functions in''' and '''Dollar 2($2) ''' with '''Bash.'''
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| Then again, Dollar 1($1) was substituted by "functions in" and Dollar 2($2) with "Bash".
  
 
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| It's value will be valid within the '''function''' in which it is defined.
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| Its value will be valid within the '''function''' in which it is defined.
  
 
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| '''Local variables''' are declared using keyword '''local'''
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| '''Local variables''' are declared using keyword '''local'''.
  
 
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| '''Global variable'''
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| '''Global variable''':
  
 
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| The value of a '''global variable''' can be accessed throughout a '''Bash '''script.
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| The value of a '''global variable''' can be accessed throughout a '''Bash script'''.
  
 
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| Let me open a file named '''function_(undescore)local.sh''''
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| Let me open a file named '''function_(underscore)local.sh''''.
  
 
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| Function name is '''say_(underscore) hello'''
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| '''Function''' name is '''say_(underscore) hello'''.
  
 
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|03:43
 
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| Here, '''variable''' '''first_name '''is declared with '''keyword''' '''local.'''
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| Here, '''variable''' '''first_name '''is declared with '''keyword''' '''local'''
  
 
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|Which means, its value will be valid within the function '''say_hello '''only.
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|which means its value will be valid within the function '''say_hello '''only.
  
 
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| A '''variable '''declared without any keyword,is treated as a '''global variable'''.
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| A '''variable '''declared without any keyword is treated as a '''global variable'''.
  
 
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|So, the '''variable last_name '''can be accessed throughout the script.
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|So, the '''variable last_name '''can be accessed throughout the '''script'''.
  
 
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|And '''last_name'''
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|and '''last_name'''.
  
 
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| Once again, we will call the '''function '''here.
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| Once again, we will '''call''' the '''function '''here.
  
 
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| 04:34
 
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| We pass two '''arguments''' to this''' function call''', namely, '''“Pratik” '''and''' “Patil”.'''
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| We pass two '''arguments''' to this''' function call''', namely- “Pratik” and “Patil”.
  
 
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| These '''echo statements''' will display the value of variables  
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| These '''echo statements''' will display the value of '''variables'''
  
 
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| '''$middle_name '''and '''$last_name'''
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| '''$middle_name '''and '''$last_name'''.
  
 
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| Save the file and go to the '''terminal.'''
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| '''Save''' the file and go to the '''terminal.'''
  
 
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| Type '''chmod space plus x space function underscore local dot sh'''
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| Type: '''chmod space plus x space function underscore local dot sh'''.
  
 
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| Type '''dot slash function underscore local dot sh'''
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| Type: '''dot slash function underscore local dot sh'''
  
 
|-
 
|-

Revision as of 11:49, 6 July 2015

Time Narration
00:01 Welcome to the spoken tutorial on More on functions.
00:06 In this tutorial, we will learn:
00:09 * To pass an argument to a function;
00:11 * To define local variable within a function and
00:16 * To define global variable in a function
00:19 with the help of some examples.
00:23 To follow this tutorial, you should have knowledge of Shell Scripting in BASH.
00:28 If not, for relevant tutorials, please visit our website which is as shown: (http://www.spoken-tutorial.org)
00:35 For this tutorial, I am using:
00:37 * Ubuntu Linux 12.04 Operating System
00:42 * GNU BASH version 4.2.
00:45 Please note, GNU Bash version 4 or above is recommended to practice this tutorial.
00:52 Let us first learn how to pass an argument to a function and its usage.
00:59 Let me open a file 'function_(underscore) parameters.sh' .
01:05 This is the shebang line.
01:08 Our function name is say_(underscore)welcome.
01:13 Open curly bracket opens the function definition.
01:18 $(Dollar)1 is the first positional parameter.
01:22 $(Dollar)2 is the second positional parameter.
01:26 Close curly bracket closes the function definition.
01:30 Here, the function 'say_welcome' is called with arguments.
01:35 The syntax is- function name i.e. "say_welcome" followed by the arguments within double quotes, i.e. "Bash" and "learning".
01:49 In a similar manner, I will call the same function with a different set of arguments. So, I havesay_welcome space within double quotes functions in space and within double quotes Bash.
02:05 Save the file and go to the terminal.
02:08 Type: chmod space plus x space function underscore parameters dot sh.
02:17 Press Enter.
02:19 Type: dot slash function underscore parameters dot sh.
02:26 Press Enter.
02:28 We see that the positional parameters were substituted by the arguments passed to a function.
02:36 Dollar 1($1) was substituted by the string "Bash" and Dollar 2($2) with "learning".
02:45 Then again, Dollar 1($1) was substituted by "functions in" and Dollar 2($2) with "Bash".
02:55 In Bash, variables can be declared as local variables and global variables.
03:01 Local variable:
03:03 Its value will be valid within the function in which it is defined.
03:10 Local variables are declared using keyword local.
03:15 Global variable:
03:17 The value of a global variable can be accessed throughout a Bash script.
03:24 Let us learn these 2 ways to declare a variable within a function.
03:29 Let me open a file named function_(underscore)local.sh'.
03:35 This is the shebang line.
03:39 Function name is say_(underscore) hello.
03:43 Here, variable first_name is declared with keyword local
03:49 which means its value will be valid within the function say_hello only.
03:55 A variable declared without any keyword is treated as a global variable.
04:01 So, the variable last_name can be accessed throughout the script.
04:08 In this echo line, we will display the value of variables
04:12 first_name,
04:14 middle_name
04:15 and last_name.
04:17 After this, we close the function.
04:21 Now, here the variable middle_name is declared without keyword. So, its value will be global throughout the script.
04:30 Once again, we will call the function here.
04:34 We pass two arguments to this function call, namely- “Pratik” and “Patil”.
04:41 These echo statements will display the value of variables
04:45 $first_name,
04:46 $middle_name and $last_name.
04:51 Please keep in mind that variable first_name is a local variable.
04:57 Save the file and go to the terminal.
05:00 Type: chmod space plus x space function underscore local dot sh.
05:09 Press Enter.
05:11 Type: dot slash function underscore local dot sh
05:16 Press Enter.
05:18 The first line of output displays the message Hello Pratik K Patil.
05:25 Here, the variable first_name that contains value Pratik is local.
05:31 Which means the value is limited to the function.
05:35 Now, let us see how the local variable behaves outside the function.
05:41 Here, nothing is displayed in first_name.
05:44 This is because the value of first_name is local to the function. And it is not available outside the function.
05:53 middle_name and last_name are printed as they are global variables.
05:59 Hope the difference is clear to you.
06:02 Let us now summarise.
06:04 In this tutorial, we learnt
06:07 To pass arguments to a function .To declare Local variable in a function
06:14 To declare Global variable in a function. with the help of a few examples
06:20 As an assignment.
06:22 Write a program,
06:23 Where the function accepts two arguments. The function should multiply the two arguments.
06:31 Make 3 function calls with arguments (1, 2), (2, 3) and (3, 4)
06:39 Watch the video available at the link shown below.
06:43 It summarises the Spoken Tutorial project.If you do not have good bandwidth, you can download and watch it.
06:51 The Spoken Tutorial Project Team.Conducts workshops using spoken tutorials. Gives certificates to those who pass an online test
07:00 For more details, please write to contact@spoken-tutorial.org
07:07 Spoken Tutorial Project is a part of the Talk to a Teacher project.
07:11 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
07:26 The script has been contributed by FOSSEE and Spoken-Tutorial teams.
07:31 This is Ashwini Patil from IIT Bombay signing off.Thank you for joining.

Contributors and Content Editors

Pratik kamble, Sandhya.np14

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