BASH/C2/Basics-of-Shell-Scripting/English-timed - Revision history

PoojaMoolya at 06:01, 12 May 2017

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Pratik kamble at 09:55, 23 March 2017

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PoojaMoolya at 06:18, 22 February 2017

2017-02-22T06:18:02Z

Pratik kamble at 10:50, 20 February 2017

2017-02-20T10:50:25Z

Sandhya.np14 at 10:13, 9 July 2015

2015-07-09T10:13:59Z

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Sandhya.np14 at 02:59, 2 July 2015

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Sandhya.np14 at 02:56, 2 July 2015

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Pratik kamble: Created page with " {| Border=1 |'''Time''' |'''Narration''' |- | 00:01 | Welcome to the spoken tutorial on '''Basics of Shell Scripting.''' |- | 00:05 | In this tutorial, we will learn about..."

2014-11-18T11:31:37Z

Created page with " {| Border=1 |'''Time''' |'''Narration''' |- | 00:01 | Welcome to the spoken tutorial on '''Basics of Shell Scripting.''' |- | 00:05 | In this tutorial, we will learn about..."

New page

{| Border=1
|'''Time'''
|'''Narration'''

|-
| 00:01
| Welcome to the spoken tutorial on '''Basics of Shell Scripting.'''

|-
| 00:05
| In this tutorial, we will learn about

|-
| 00:09
|* '''System variables'''

|-
| 00:11
|* '''User defined variables''' and

|-
| 00:13
|* Accepting user input via keyboard

|-
| 00:16
| To follow this tutorial you should be familiar with '''Linux Operating System'''

|-
| 00:23
|If not, for relevant tutorials please visit our website which is as shown

|-
| 00:29
| For this tutorial I am using

|-
| 00:32
|* '''Ubuntu Linux 12.04''' Operating System and

|-
| 00:35
|* '''GNU Bash''' version '''4.1.10'''

|-
| 00:40
| Please Note'''GNU Bash '''version '''4''' or above is recommended for practice.

|-
|00:46
| Let us start with a introduction to variables

|-
|00:49
| * '''Bash variables''' provide temporary storage for information

|-
| 00:55
|* These '''variables''' can be used within the lifespan of the program.

|-
| 01:01
|* There are two types of variables
# '''System variables'''
# '''User defined variables '''

|-
| 01:07
| '''System variables''', These are created and maintained by '''Linux Bash Shell''' itself.

|-
| 01:14
|They are defined by Capital letters.

|-
| 01:17
|Commonly used '''system variables '''are

|-
| 01:20
|* '''BASH_VERSION, '''

|-
| 01:21
|* '''HOSTNAME, '''

|-
| 01:23
|* '''HOME etc'''

|-
| 01:25
| Let us open the terminal by pressing '''Ctrl Alt and T''' keys simultaneously on your keyboard.

|-
| 01:33
| Now type '''set''' and press '''Enter.'''

|-
| 01:38
|This will display all the '''system variables'''.

|-
| 01:42
| Alternately, you can type '''env''' or '''printenv,''' to view all the '''system variables.'''

|-
|01:53
|Let me clear the prompt

|-
| 01:55
| Now, type '''echo''' space within double quotes '''dollar sign''' '''HOSTNAME'''

|-
| 02:01
|and Now press '''Enter.'''

|-
| 02:04
|The '''hostname''' of the system will be displayed.

|-
| 02:07
| Now let's find out the full path of '''home'''directory.

|-
| 02:11
| Type '''echo''' space within double quotes '''dollar sign HOME'''(in Capital)

|-
| 02:18
| Press '''Enter.'''

|-
| 02:21
|The full path of user's '''home''' directory will be displayed.

|-
|02:26
| Now, type

|-
| 02:27
|'''echo''' space within double quotes '''HOME''' (in capital)

|-
| 02:32
|Press '''Enter.'''

|-
| 02:34
|This will display only the '''HOME''' not the value of '''HOME''' variable.

|-
|02:39
|So it is neccessary to use '''dollar sign( '$') '''at the beginning of every variable, to display its value.

|-
|02:48
|Let us switch back to our slides

|-
| 02:51
|'''User Defined Variables'''

|-
| 02:53
|* These '''variables''' are created and maintained by users.

|-
| 02:57
|* It is always a good idea to avoid '''uppercase''' for the names of '''user defined variables'''.

|-
| 03:05
|* This makes it easy to differentiate between '''user defined '''and '''system variables'''.

|-
|03:12
| Switch back to our terminal

|-
| 03:14
| Type '''username equal to sign sunita'''

|-
| 03:20
|Please note that there should not be any blank space between '''username''', '''equal to '''sign and '''sunita'''.

|-
| 03:29
|Now press '''Enter.'''

|-
| 03:30
| To display the value of variable '''username'''

|-
| 03:33
|Type '''echo''' space within double quotes '''dollar sign username'''

|-
|03:40
| press '''Enter'''

|-
| 03:42
|This will display '''sunita '''on your '''terminal.'''

|-
| 03:46
| The value of a variable can be unset,

|-
|03:50
|Let us switch back to our slide

|-
|03:52
|'''unset''', the value of variable can be unset by using the '''unset''' command

|-
|03:59
|The syntax for this is '''unset variablename'''

|-
| 04:03
| Let's use the previous example where '''username '''is our variable.

|-
| 04:08
| Switch to the '''Terminal'''. Now type '''unset space username''' press '''Enter'''

|-
| 04:18
|Let us check Type '''echo''' space within double quotes '''dollar sign username ''' press '''Enter.'''

|-
| 04:28
|Nothing will be displayed on the '''terminal'''.

|-
| 04:30
|This means that the value of '''variable username''' has been removed.

|-
|04:36
|Now switch back to our slide

|-
| 04:39
|'''Global''' and '''local variables.'''

|-
|04:42
| * In '''Shell '''script,''' user defined variables''' can be declared '''globally''' or '''locally. '''

|-
| 04:49
|* By default, all '''variables''' are '''global.'''

|-
| 04:52
|* This means, their values remains the same inside and outside the '''function'''.

|-
| 04:59
| Let us learn how to declare '''variables''' '''globally''' and '''locally.'''

|-
| 05:04
| Switch to the '''terminal '''and type

|-
| 05:07
|'''gedit''' '''space g_(underscore)variable.sh space &''' (ampersand sign)

|-
|05:16
|'''gedit''' is the text editor '''g_'''(underscore) '''variable.sh''' is our file name

|-
|05:23
|and & (ampersand) is use to free up the prompt.

|-
| 05:28
| press''' Enter.'''

|-
| 05:30
| Type the code as shown here, in your''' g_(underscore)variable.sh '''file.

|-
| 05:35
| Let me explain the code now.

|-
| 05:38
| The first line, with the '''hash '''and '''exclamation '''symbol, is a '''shebang''' or a '''bang''' line.

|-
| 05:44
| '''username=sunita '''is the '''userdefined variable '''and it is declared '''globally.'''

|-
| 05:51
| '''echo '''will display the string '''outside function: ''' And

|-
| 05:55
|'''dollar username''' will print the value of the variable '''username.'''

|-
| 06:00
|This is how we defined a '''function''' in '''BASH''' script.

|-
| 06:04
|We will discuss about''' functions '''in detail, in later tutorials.

|-
| 06:09
| This is the body of the '''function'''.

|-
| 06:12
|Here another message '''inside function '''will be displayed, along with the value of '''username.'''

|-
| 06:19
| Here, we call the function

|-
| 06:21
|This is our code. Now let's execute it.

|-
| 06:23
| Come back to our '''Terminal. '''

|-
|06:26
|Let me clear the prompt

|-
| 06:28
|First we need to make our file executable.

|-
| 06:31
|Type '''chmod''' '''space plus x space g_(underscore)variable.sh''' press '''Enter'''

|-
|06:39
|Now type '''dot slash g_(Underscore)variable.sh'''

|-
| 06:45
|Press '''Enter'''

|-
| 06:47
| Observe the output.

|-
| 06:48
|Outside the function, '''username '''takes the value '''sunita.'''

|-
| 06:53
|Inside the function also, '''username''' takes the same value '''sunita'''.

|-
| 06:59
| This is because '''username''' was declared '''globally '''outside the function.

|-
| 07:04
| Next, let us learn how to declare a variable '''locally'''.

|-
|07:09
| Type '''gedit''' '''space l_(Underscore)variable.sh space &''' (ampersand sign)

|-
| 07:18
| Press''' Enter.'''

|-
| 07:20
| Type the code as shown here, in your '''l_(underscore)variable.sh '''file.

|-
| 07:25
| Let me explain the code.

|-
| 07:28
| The code is the same as before, except for an extra line of code inside the function.

|-
|07:36
| Inside the '''function''' block, we have a line,'''local''' '''space username equals to jack'''

|-
| 07:41
| This assigns a new value for the variable '''username locally'''.

|-
| 07:48
| Now switch to the '''Terminal. '''

|-
| 07:50
|Let's make file executable

|-
| 07:52
|By Typing '''chmod''' '''space plus x space l_variable.sh'''

|-
| 08:00
| Press '''Enter.'''

|-
| 08:02
|Type '''dot slash l_variable.sh'''

|-
| 08:07
|Press '''Enter.'''

|-
|08:08
|The output is displayed

|-
| 08:10
| Outside the '''function''', '''username''' takes the value '''sunita.'''

|-
| 08:15
|Whereas inside the '''function''', '''username''' takes the value '''jack'''.

|-
| 08:20
|This is because '''username''' is assigned this value '''locally,''' within the function.

|-
| 08:26
| Now let us quickly see how to get user input via keyboard.

|-
| 08:31
|The '''read''' command is used to accept input from the keyboard.

|-
| 08:36
|It can also be used to assign an input value to a '''user defined variable'''.

|-
| 08:41
| The syntax of '''read '''command is

|-
| 08:44
|'''read space hyphen p space within double quotes PROMPT '''

|-
| 08:50
|Please note that '''PROMPT''' is just a string, that waits for user input.

|-
| 08:55
|You may replace it with your own string.

|-
| 08:58
| Now Switch to the '''terminal '''

|-
| 09:00
|Type'''gedit''' '''space read.sh space & ''' (ampersand sign)

|-
| 09:08
|Press '''Enter.'''

|-
| 09:09
| Type the code as shown, in your''' read.sh '''file.

|-
| 09:14
| Let me explain the code.

|-
| 09:16
| In this example, input is given from the keyboard by the user.

|-
| 09:21
| This is the '''bang''' line.

|-
| 09:23
| Here '''-p '''displays the prompt, without a newline and takes input from the keyboard.

|-
| 09:31
|The user input will be stored in the variable '''username'''.

|-
| 09:36
| '''echo '''command displays the message

|-
| 09:38
|'''Hello''' and the name entered by the user, via the keyboard.

|-
| 09:43
|So, let us execute the programme.

|-
|09:45
| Come back to our terminal

|-
| 09:49
|Type '''chmod''' '''space plus x space read.sh'''

|-
| 09:55
| press '''Enter.'''

|-
| 09:56
| Type'''dot slash read.sh''' press '''Enter.'''

|-
| 10:01
| Here it is displayed '''Enter username: '''

|-
| 10:04
|I will type '''ashwini''' press '''Enter.'''

|-
| 10:08
| The message''' Hello ashwini''' is displayed.

|-
| 10:13
|'''ashwini''' was assigned as an input value to the user defined variable '''username.'''

|-
|10:20
|Let us go back to our slide and summarise.

|-
| 10:23
| In this tutorial we learnt,

|-
| 10:26
|* '''System variables '''

|-
| 10:27
|* '''User defined variables'''

|-
| 10:29
|* Accepting user input via keyboard

|-
| 10:33
| As an assignment

|-
|10:34
| Write a simple '''Bash''' program to get the following system variables

|-
| 10:38
|* '''pwd ''' and * '''logname'''

|-
| 10:41
| Write a simple '''Bash''' program

|-
| 10:43
|* To ask '''username''' from user''' '''

|-
| 10:46
|* To exit the program, if user does not enter anything, within 10 seconds

|-
| 10:51
|* {Hint: '''read -(Hyphen)t 10 -(Hyphen)p}'''

|-
| 10:56
| Watch the video available at the link shown below.

|-
| 10:59
|It summarises the Spoken Tutorial project

|-
| 11:02
|If you do not have good bandwidth, you can download and watch it

|-
| 11:07
| The Spoken Tutorial Project Team Conducts workshops using spoken tutorials Gives certificates to those who pass an online test

|-
| 11:16
|For more details, please write to contact@spoken-tutorial.org

|-
|11:23
| Spoken Tutorial Project is a part of the Talk to a Teacher project

|-
| 11:27
|It is supported by the National Mission on Education through ICT, MHRD, Government of India

|-
| 11:34
|More information on this Mission is available at the link shown below http://spoken-tutorial.org\NMEICT-Intro

|-
| 11:40
| The script has been contributed by FOSSEE and Spoken Tutorial Teams.

|-
| 11:44
| This is Ashwini Patil from IIT Bombay.Signing off.Thank you for joining.

|}

@@ Line 510: / Line 510: @@
 |-
 | 09:55
-| press '''Enter.'''
+| press '''Enter.'''  Type: '''dot slash read.sh'''  press '''Enter.'''
-−
-|-
-| 09:56
-| Type: '''dot slash read.sh'''  press '''Enter.'''
 |-

@@ Line 134: / Line 134: @@
 |-
 |02:26
-| Now, type:
+| Now, type:'''echo''' space within double quotes '''HOME''' (in capital).
-−
-|-
-| 02:27
-|'''echo''' space within double quotes '''HOME''' (in capital).
 |-
@@ Line 186: / Line 182: @@
 |-
 | 03:29
-|Now, press '''Enter.'''
+|Now, press '''Enter.''' To display the '''value''' of '''variable''' '''username''',
-−
-|-
-| 03:30
-| To display the '''value''' of '''variable''' '''username''',
 |-

@@ Line 62: / Line 62: @@
 |-
 | 01:01
-| There are two types of variables:
+| There are two types of variables: '''System variables''','''User defined variables '''.
 '''System variables'''
 '''User defined variables '''.
 |-
@@ Line 80: / Line 78: @@
 |-
 | 01:20
-| '''BASH_VERSION '''
+| '''BASH_VERSION '''. '''HOSTNAME '''
-−
-|-
-| 01:21
-| '''HOSTNAME '''
 |-
@@ Line 364: / Line 358: @@
 |-
 | 06:47
-| Observe the '''output'''.
+| Observe the '''output'''. Outside the function, '''username '''takes the value '''sunita.'''
-−
-|-
-| 06:48
-|Outside the function, '''username '''takes the value '''sunita.'''
 |-
@@ Line 432: / Line 422: @@
 |-
 | 08:07
-|Press '''Enter.'''
+|Press '''Enter.'''The '''output''' is displayed.
-−
-|-
-|08:08
-|The '''output''' is displayed.
 |-
@@ Line 488: / Line 474: @@
 |-
 | 09:08
-|Press '''Enter.'''
+|Press '''Enter.''' Type the code as shown here in your  "read.sh" file.
-−
-|-
-| 09:09
-| Type the code as shown here in your  "read.sh" file.
 |-
@@ Line 568: / Line 550: @@
 |-
 | 10:26
-|'''System variables '''
+|'''System variables ''', '''User defined variables''' and
-−
-|-
-| 10:27
-| '''User defined variables''' and
 |-
@@ Line 580: / Line 558: @@
 |-
 | 10:33
-|  As an assignment-
+|  As an assignment- Write a simple '''Bash''' program to get the following '''system variables'''.
-−
-|-
-|10:34
-| Write a simple '''Bash''' program to get the following '''system variables'''.
 |-

@@ Line 14: / Line 14: @@
 |-
 | 00:09
-|* '''System variables'''
+|'''System variables'''
 |-
 | 00:11
-|* '''User defined variables''' and
+| '''User defined variables''' and
 |-
 | 00:13
-|* Accepting user input via keyboard.
+| Accepting user input via keyboard.
 |-
@@ Line 38: / Line 38: @@
 |-
 | 00:32
-|* '''Ubuntu Linux 12.04''' Operating System and
+| '''Ubuntu Linux 12.04''' Operating System and
 |-
 | 00:35
-|* '''GNU Bash''' version '''4.1.10'''
+| '''GNU Bash''' version '''4.1.10'''
 |-
@@ Line 63: / Line 63: @@
 | 01:01
 | There are two types of variables:
-# '''System variables'''
+'''System variables'''
-# '''User defined variables '''.
+'''User defined variables '''.
 |-
@@ Line 80: / Line 80: @@
 |-
 | 01:20
-|* '''BASH_VERSION '''
+| '''BASH_VERSION '''
 |-
 | 01:21
-|* '''HOSTNAME '''
+| '''HOSTNAME '''
 |-
 | 01:23
-|* '''HOME etc.'''
+| '''HOME etc.'''
 |-
@@ Line 568: / Line 568: @@
 |-
 | 10:26
-|* '''System variables '''
+|'''System variables '''
 |-
 | 10:27
-|* '''User defined variables''' and
+| '''User defined variables''' and
 |-
 | 10:29
-|* Accepting user input via keyboard.
+| Accepting user input via keyboard.
 |-
@@ Line 588: / Line 588: @@
 |-
 | 10:38
-|* '''pwd ''' and * '''logname'''.
+| '''pwd ''' and * '''logname'''.
 |-
 | 10:41
-|* Write a simple '''Bash''' program
+| Write a simple '''Bash''' program
 |-
@@ Line 621: / Line 621: @@
 | 11:07
 | The Spoken Tutorial Project team:
-* Conducts workshops using spoken tutorials.
+Conducts workshops using spoken tutorials.Gives certificates to those who pass an online test.
-* Gives certificates to those who pass an online test.
 |-

@@ Line 604: / Line 604: @@
 |-
 | 10:51
-|* {Hint: '''read -(Hyphen)t 10 -(Hyphen)p}'''
+| {Hint: '''read -(Hyphen)t 10 -(Hyphen)p'''}
 |-