Difference between revisions of "BOSS-Linux/C3/More-on-sed-command/English-timed"

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Revision as of 12:37, 24 March 2017

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 Linux Operating System and
00:20 GNU BASH version 4.2.24
00:23 Please note, GNU Bash version 4 or above is recommended to practice this tutorial.
00:30 As prerequisites,
00:33 you should know basics of Linux terminal.
00:36 You should be aware of sed tool.
00:39 For relevant tutorials, please visit our website which is as shown: http://spoken-tutorial.org
00:45 The major use of sed is substitution.
00:49 Replacing some pattern in the input with something else.
00:54 Let's first look at the original file seddemo.txt.
01:00 Notice that 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’,
01:15 type on the terminal:
01:17 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.
01:39 Press Enter.
01:42 Notice the fourth line.
01:45 Only the first occurrence of Kumar is changed to Roy, not the second one.
01:51 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.
02:02 This is because, by default, the first matched entry of any line is substituted.
02:10 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.
02:47 We can make multiple substitutions in one go as well.
02:52 Say, we want to replace the word "electronics" with the word "electrical"
02:57 and "civil" with "metallurgy" in the file seddemo.txt.
03:04 Let me clear the prompt.
03:06 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
03:35 press Enter.
03:38 You can see that the words are replaced.
03:41 Now we want to change the stream of "Anirban" from "computers" to "mathematics".
03:49 In such case, we would need to type:
03:52 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.
04:13 We see that the stream is changed.
04:17 Let us understand what this is.
04:20 First we write sed, then in single quotes we write the pattern to be matched.
04:27 This is "Anirban".
04:29 Now after the slash comes the operation.
04:33 This is s that stands for substitution as we have already seen.
04:40 Then we mention the pattern to be replaced which is "computers".
04:46 Then the new word that would be substituted which is "mathematics".
04:52 We can also use sed to add or delete lines in the file.
04:59 Say, we want to select those lines which do not have stream as "electronics".
05:05 For that, we have the d flag.
05:09 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
05:30 Press Enter.
05:32 To see the contents, type: cat space nonelectronics.txt.
05:41 Say, at the start of the file we want to add a line Student Information.
05:49 For that we have the i action.
05:53 We need to type: sed space in single quotes '1i space Student Information' after the quote seddemo.txt
06:09 press Enter.
06:12 You can see the output.
06:14 In fact, we can enter multiple lines like this.
06:19 Say, we want to add the two lines we would do it in a similar way.
06:25 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 backslash n 2013' after the quotes seddemo.txt.
06:54 press Enter.
06:56 Notice backslash n between the string ‘Information’ and ‘2013’.
07:04 backslash n prints 2013 in the next line after ‘Student Information’.
07:10 This brings us to the end of this tutorial.
07:14 Let us summarize.
07:16 In this tutorial, we learnt:
07:18 * Substitution
07:19 * Replacement and
07:20 * Insertion.
07:23 As an assignment, use the same text file seddemo.txt
07:29 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 summarizes the Spoken Tutorial project.
07:41 If you do not have good bandwidth, you can download and watch it.
07:46 The Spoken Tutorial Project team: Conducts workshops using spoken tutorials.
07:52 Gives certificates to those who pass an online test.
07:56 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.
08:07 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