Linux/C3/More-on-sed-command/English-timed
From Script | Spoken-Tutorial
| 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 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", |
| 01:16 | 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 word "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 | 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 space 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 us to the end of this tutorial. |
| 07:14 | Let us summarize, |
| 07:17 | In this tutorial we learnt: |
| 07:19 | Substitution 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 summarizes 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. |
