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Revision as of 12:54, 12 February 2015
| 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 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 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 words 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 | And 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 | And 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 slash n 2013' after the quotes seddemo.txt |
| 06:54 | Press Enter |
| 06:56 | Notice slash n between the string ‘Information’ and ‘2013’. |
| 07:04 | slash n prints 2013 in the next line after ‘Student Information’ |
| 07:10 | This brings me to the end of this tutorial. |
| 07:14 | Let us summarize, |
| 07:16 | In this tutorial we learnt, |
| 07:18 | Substitution |
| 07:19 | Replacement |
| 07:20 | And 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 summarises 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. |
