Difference between revisions of "BASH/C3/Here-document-and-Here-string/English-timed"

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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
  
 
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|* '''Ubuntu Linux''' 12.04''' '''Operating System  
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|'''Ubuntu Linux''' 12.04''' '''Operating System  
  
 
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|* '''GNU BASH''' version 4.2
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|'''GNU BASH''' version 4.2
  
 
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|  Let us learn about '''Here document'''.
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|  Let us learn about ''''Here' document'''.
  
 
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|* It is a special purpose block of text or code.  
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|It is a special purpose '''block''' of '''text''' or '''code'''.  
  
 
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|* It is a form of I/O redirect.
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| It is a form of '''I/O redirect'''.
  
 
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|* It feeds a command list to an interactive program or command line.
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|It feeds a command list to an interactive program or '''command line'''.
  
 
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|* It can be treated as a separate file.
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|It can be treated as a separate file.
  
 
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|* It can also be treated as multiple line input redirected to a '''shell script'''.
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|It can also be treated as multiple line '''input''' redirected to a '''shell script'''.
  
 
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|  Syntax is-
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|  Syntax is-'''command space less than less than space HERE'''.
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|'''command space less than less than space HERE'''.
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| '''wc''' represents word count.  
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| 'wc' represents '''word count'''.  
  
 
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|The block of code or text until the second occurrence of '''HERE''' will be treated as a file.  
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|The '''block''' of code or '''text''' until the second occurrence of '''HERE''' will be treated as a file.  
  
 
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|  '''HERE''' acts as a '''delimiter''' for '''wc hyphen w''' command while reading multi-line input.
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|  '''HERE''' acts as a '''delimiter''' for '''wc hyphen w''' command while reading '''multi-line input'''.
  
 
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|If we try to '''execute''' the same command in the '''terminal''', we should get ''''4'''' as an output.
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|If we try to '''execute''' the same command in the '''terminal''', we should get '4' as an output.
  
 
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|This is because we have passed four words to the command ''''wc hyphen w''''.  
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|This is because we have passed four words to the command '''wc hyphen w'''.  
  
 
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|that is, number of words in '''Here document '''is '''4.'''
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|that is, number of words in ''''Here' document '''is 4.
  
 
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|  Come back to the program.
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|  Come back to our program.
  
 
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|Let us add two more words here at the beginning of the text.
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|Let us add two more words here, at the beginning of the text.
  
 
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|  We can also pass an '''argument''' to the '''Here document.'''
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|  We can also pass an '''argument''' to the '''Here''' document.
  
 
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|  Here we have to close the '''document''' using the same '''delimiter''', '''this.'''
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|  Here we have to close the '''document''' using the same '''delimiter''' '''this.'''
  
 
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|  '''Save''' the file.
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|  '''Save''' the file. Let us now '''execute''' the program.
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|  Let us now '''execute''' the program.
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|'''1st argument is: Sunday'''
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|'''"1st argument is: Sunday"'''
  
 
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|'''2nd argument is: Monday '''.
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|'''"2nd argument is: Monday" '''.
  
 
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|* '''Here string '''is used for '''input redirection''' from '''text''' or a '''variable'''.
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|'''Here''' string is used for '''input redirection''' from '''text''' or a '''variable'''.
  
 
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|* The '''input''' is mentioned in the same line within single quotes.
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|The '''input''' is mentioned in the same line within single quotes.
  
 
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|Number of words in '''here document''' is '''6''' and number of words in '''here string''' is''' 4.'''
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|Number of words in '''here''' document is 6 and number of words in '''here''' string is 4.
  
 
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|  Likewise, you can write your own '''Here strings.'''
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|  Likewise, you can write your own '''Here''' strings.
  
 
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|* '''HERE document'''
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|'''HERE''' document
  
 
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|* '''HERE string'''.  
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|'''HERE''' string.  
  
 
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|* '''Here document'''
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|'''Here document''''''Here string'''.
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|* '''Here string'''.
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|  The Spoken Tutorial project team: Conducts workshops using spoken tutorials.
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|  The Spoken Tutorial project team:   Conducts workshops using spoken tutorials.
  
 
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|This is Ashwini Patil from IIT Bombay. signing off
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|This is Ashwini Patil from IIT Bombay, signing off.
  
 
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Latest revision as of 17:24, 23 March 2017

Time Narration
00:01 Dear friends, welcome to the spoken tutorial on HERE document and strings.
00:08 In this tutorial, we will learn about
00:11 special-purpose redirection called Here documents and Here strings
00:17 with the help of some examples.
00:20 To follow this tutorial, you should have knowledge of Shell Scripting in BASH.
00:26 If not, for relevant tutorials, please visit our website which is as shown. http://www.spoken-tutorial.org
00:32 For this tutorial, I am using:
00:34 Ubuntu Linux 12.04 Operating System
00:39 GNU BASH version 4.2
00:42 Please note, GNU Bash version 4 or above is recommended for practice.
00:49 Let us learn about 'Here' document.
00:52 It is a special purpose block of text or code.
00:56 It is a form of I/O redirect.
01:00 It feeds a command list to an interactive program or command line.
01:06 It can be treated as a separate file.
01:10 It can also be treated as multiple line input redirected to a shell script.
01:17 Syntax is-command space less than less than space HERE.
01:24 After this, on the next line, we can give the text inputs.
01:29 It can consist of any number of lines.
01:33 Here, text1, text2, textN are the text inputs.
01:40 After the text inputs, on the next line, we type the keyword HERE again.
01:46 It denotes the closing of HERE document.
01:50 Let us understand this with an example.
01:53 I will open a file named here dot sh .
01:59 The first line of code is the shebang line.
02:04 Let me put a block of code after this line.
02:09 'wc' represents word count.
02:12 wc hyphen w counts the number of words in the HERE document.
02:20 The block of code or text until the second occurrence of HERE will be treated as a file.
02:28 The content present in HERE document is an input to the command wc hyphen w.
02:36 HERE acts as a delimiter for wc hyphen w command while reading multi-line input.
02:47 If we try to execute the same command in the terminal, we should get '4' as an output.
02:55 This is because we have passed four words to the command wc hyphen w.
03:03 Now click on Save to save the file.
03:06 Let us switch to the Terminal using Ctrl, Alt and T keys simultaneously on your keyboard.
03:15 Type: chmod space plus x space here dot sh
03:22 Press Enter.
03:24 Type: dot slash here dot sh
03:27 Press Enter.
03:30 We can see the output as 4
03:33 that is, number of words in 'Here' document is 4.
03:38 Come back to our program.
03:41 Let us add two more words here, at the beginning of the text.
03:47 Hello and welcome to Bash learning.
03:52 Click on Save.
03:54 Let us execute the program again.
03:57 On the terminal, type: dot slash here dot sh
04:04 Press Enter.
04:06 Now the output is 6 because we added two more words to our text.
04:13 We can also pass an argument to the Here document.
04:18 Let us see how to do this with an example.
04:22 Let me open a file named hereoutput dot sh.
04:28 The command cat will concatenate files and print the standard output.
04:35 Note that we have used the string "this" instead of "HERE".
04:41 It’s not necessary that you always have to use the delimiter HERE.
04:47 You can use any other delimiter also.
04:51 This line will display the 0th (zeroth) argument.
04:55 The 0th (zeroth) argument, by default, is the filename.
05:00 This line will display the 1st argument passed to the program.
05:05 And this line will display the 2nd argument passed to the program.
05:09 Here we have to close the document using the same delimiter this.
05:17 Save the file. Let us now execute the program.
05:21 On the terminal, type: chmod space plus x space hereoutput dot sh.
05:29 Press Enter
05:32 Type: dot slash hereoutput dot sh space Sunday space Monday
05:40 The output is displayed as:
05:43 "0'th argument is: dot salsh hereoutput dot sh" which is the filename.
05:49 "1st argument is: Sunday"
05:51 "2nd argument is: Monday" .
05:55 Let us learn about "Here" string now.
05:59 Here string is used for input redirection from text or a variable.
06:06 The input is mentioned in the same line within single quotes.
06:12 The syntax is- command space three 'less than symbols' space within single quotes write string
06:22 Let us understand this with an example.
06:25 I will open the same file here dot sh.
06:30 Here at the end, I will type: wc space hyphen w three less than symbols space within single quotes Welcome to Bash learning.
06:44 This will redirect the string within quotes to the command wc hyphen w.
06:52 Now click on Save to save the changes.
06:55 We will switch to the Terminal.
06:58 Now type: dot slash here dot sh.
07:03 We can see the output as 6 and 4.
07:08 Number of words in here document is 6 and number of words in here string is 4.
07:15 Likewise, you can write your own Here strings.
07:20 This brings us to the end of this tutorial.
07:23 Let us summarize.
07:25 In this tutorial, we learnt about:
07:27 HERE document
07:29 HERE string.
07:31 As an assignment, convert a string to uppercase using:
07:36 'Here document'Here string.
07:39 Hint: tr space a hyphen z space capital A hyphen capital Z.
07:47 This is the command to convert characters from lower to upper case.
07:54 Watch the video available at the link shown below.
07:57 It summarizes the Spoken-Tutorial project.
08:01 If you do not have good bandwidth, you can download and watch it.
08:06 The Spoken Tutorial project team: Conducts workshops using spoken tutorials.
08:12 Gives certificates to those who pass an online test.
08:17 For more details, please write to contact@spoken-tutorial.org
08:25 Spoken Tutorial Project is a part of the Talk to a Teacher project.
08:29 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
08:38 More information on this mission is available at the link shown below.

http://spoken-tutorial.org\NMEICT-Intro

08:44 The script has been contributed by FOSSEE and Spoken-Tutorial teams.
08:50 This is Ashwini Patil from IIT Bombay, signing off.
08:54 Thank you for joining.

Contributors and Content Editors

Gaurav, PoojaMoolya, Pratik kamble, Sandhya.np14

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