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

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