BOSS-Linux/C3/More-on-sed-command/English-timed

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Time Narration
00:01 Welcome to the spoken tutorial on More on sed.
00:06 In this tutorial, we will learn some More on sed commands, through some examples.
00:13 To record this tutorial, I am using
00:15 *Ubuntu Linux version 12.04 Operating System and
00:20 *GNU BASH version 4.2.24
00:24 Please note, GNU Bash version 4 or above is recommended to practice this tutorial.
00:32 As prerequisites,
00:34 You should know basics of Linux terminal.
00:37 You should be aware of sed tool.
00:40 For relevant tutorials please visit our website which as shown: http://spoken-tutorial.org
00:46 The major use of sed is substitution.
00:49 Replacing some pattern in the input with something else.
00:55 Let's first look at the original file seddemo.txt
01:01 Notice the word Kumar occurs two times in the fourth line and once in the sixth line.
01:10 If you want to replace all occurrences of ‘Kumar’ with ‘Roy’
01:16 Type on the terminal
01:18 sed space within single quote 's front slash / opening square bracket small k capital K closing square bracket umar slash Roy slash' after the single quotes space seddemo.txt
01:40 Press Enter.
01:43 Notice the fourth line.
01:46 Only the first occurrence of Kumar is changed to Roy, not the second one.
01:52 Sixth line had one occurrence of the word Kumar and this is replaced now.
01:57 So, we see only the first entry of the lines has been changed.
02:03 This is because, by default, the first matched entry of any line is substituted.
02:11 To substitute all the matched entries we need to use the flag g option.
02:17 Let me clear the prompt.
02:20 Type:
sed space within single quotes 's front slash opening square bracket small k capital K closing square bracket umar slash Roy slash g' after the single quote space seddemo.txt Press Enter
02:43 Now, both entries of the fourth line are replaced.
02:48 We can make multiple substitutions in one go as well.
02:53 Say we want to replace the words electronics with the word electrical
02:58 And civil with metallurgy in the file seddemo.txt
03:04 Let me clear the prompt
03:07 Type:
sed space  hyphen e space within single quotes ‘s front slash electronics slash electrical slash g’  after the single quote space hyphen e space within single quotes  ‘s front slash civil slash metallurgy slash g’ after the single quotes space seddemo.txt
03:37 And press Enter.
03:39 You can see that the words are replaced.
03:43 Now we want to change the stream of Anirban from computers to mathematics.
03:49 In such case we would need to type:
03:54 sed space within single quotes 'front slash Anirban slash s slash computers slash mathematics slash g' after the single quotes space seddemo.txt
04:11 Press Enter.
04:14 We see that the stream is changed.
04:17 Let us understand what this is.
04:21 First we write sed then in single quotes we write the pattern to be matched.
04:28 This is Anirban.
04:30 Now after the slash comes the operation.
04:34 This is s that stands for substitution, as we have already seen.
04:41 Then we mention the pattern to be replaced which is computers.
04:47 Then the new word that would be substituted, which is mathematics.
04:53 We can also use sed to add or delete lines in the file.
05:00 Say we want to select those lines which do not have stream as electronics.
05:06 For that, we have the d flag.
05:10 Type:
sed space within single quotes front slash electronics slash d after the single quotes space seddemo.txt space greater than sign space nonelectronics.txt
05:31 Press Enter.
05:33 To see the contents, type: cat space nonelectronics.txt
05:43 Say, at the start of the file we want to add a line Student Information.
05:49 For that we have the i action.
05:54 We need to type: sed space in single quotes '1i space Student Information' after the quote seddemo.txt
06:10 And press Enter.
06:13 You can see the output.
06:15 In fact, we can enter multiple lines like this.
06:20 Say, we want to add the two lines we would do it in a similar way.
06:26 Along with Student Information we also want to add academics in the next year.
06:33 So in that case we would write
sed space in single quotes 1i space Student Information slash n 2013' after the quotes seddemo.txt 
06:55 Press Enter
06:57 Notice slash n between the string ‘Information’ and ‘2013’.
07:05 slash n prints 2013 in the next line after ‘Student Information’
07:12 This brings me to the end of this tutorial.
07:14 Let us summarize,
07:17 In this tutorial we learnt,
07:19 Substitution
07:20 Replacement
07:21 And Insertion
07:24 As an assignment, Use the same text file seddemo.txt
07:30 And try to replace or substitute name Ankit with Ashish
07:35 Watch the video available at the link shown below http://spoken-tutorial.org/What_is_a_Spoken Tutorial
07:39 It summarises the Spoken Tutorial project
07:42 If you do not have good bandwidth, you can download and watch it
07:47 The Spoken Tutorial Project Team Conducts workshops using spoken tutorials
07:53 Gives certificates to those who pass an online test
07:57 For more details, please write to contact@spoken-tutorial.org
08:04 Spoken Tutorial Project is a part of the Talk to a Teacher project
08:09 It is supported by the National Mission on Education through ICT, MHRD, Government of India
08:16 More information on this Mission is available at the link shown below: http://spoken-tutorial.org\NMEICT-Intro
08:22 The script has been contributed by Anirban and Sachin.
08:28 This is Ashwini PAtil from IIT bombay signing off.

Thank you for joining.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Sandhya.np14