Linux/C3/More-on-grep-command/English-timed

Time	Narration
00:01	Welcome to the spoken tutorial on More on grep.
00:05	In this tutorial we will learn
00:07	some more grep commands
00:10	through some examples.
00:13	To record this tutorial, I am using
00:16	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.
00:31	As prerequisites:
00:33	You should know Basics of Linux terminal.
00:36	You should be aware of 'grep'.
00:39	For relevant tutorials, please visit our website which is as shown: http://spoken-tutorial.org
00:45	We can match more than one patterns as well.
00:49	Then we have to use the hyphen e option.
00:53	I will use the same file 'grepdemo.txt'.
00:58	Say, we want to find information for those who are either in civil or electronics.
01:05	We need to type on the terminal:
01:07	grep space hyphen e space within double quotes electronics after the quotes space hyphen e space in double quotes civil after the quotes space grepdemo.txt
01:24	Press Enter.
01:25	The output is displayed.
01:28	Say, you need to look into people whose title is 'choudhury'.
01:33	The problem is, different people spell their titles in different way.
01:38	So what is the solution?.
01:42	In such cases we can use hyphen e option with hyphen i.
01:48	Type: grep space hyphen ie space in double quotes chaudhury after the quotes space hyphen ie space in double quotes chowdhari after the quotes space grepdemo.txt
02:12	Press Enter.
02:14	The output is displayed.
02:16	But there can be many other ways in which we can write the names.
02:23	How many hyphen e options can we give?
02:26	Obviously there needs to be a better way and that way is through Regular expressions.
02:33	A regular expression provides a concise and flexible means for matching strings of text
02:41	such as particular characters, words or patterns of characters.
02:47	There are a number of regular expression characters.
02:52	Let us see them one by one.
02:55	The character class:
02:57	It allows us to specify a group of characters within a pair of square brackets .
03:03	Only one out of this group of characters is matched.
03:08	Eg. [abc] would mean that this regular expression matches either a or b or c.
03:18	To match 'chaudhury', we may type at the prompt:
03:23	grep space hyphen i space within double quotes ch opening square bracket ao closing square bracket opening square bracket uw closing square bracket dh opening square bracket ua closing square bracket r opening square bracket yi closing square bracket after the double quotes space grepdemo.txt
03:54	Press Enter.
03:56	The output is displayed.
03:59	It still does not match 'choudhuree' with double 'e'.
04:03	If we want to specify a large range then we write:
04:08	First letter dash last letter of the range
04:13	Suppose we like to match any digit we simply write [0-9].
04:20	One out of this group of characters is matched.
04:24	The Asterisk: The asterisk refers to 0 or more occurrences of the immediately preceding character.
04:33	For example ab asterisk can match a, ab, abb, abbb etc.
04:44	So, to match the student's name whose name is Mira,
04:48	we type at the prompt:
04:51	grep space hyphen i space within double quotes m opening square bracket ei closing square bracket asterisk r a a asterisk after the quotes space grepdemo.txt
05:12	Press Enter.
05:14	The output is displayed.
05:16	The dot regular expression matches any one character.
05:21	Say, we want to search any words that are 4 letters long and starts with M.
05:29	We would simply type:
05:31	grep space within double quotes M... space after the quotes space grepdemo.txt
05:44	Press Enter.
05:46	The output is displayed.
05:48	Here, the 'space' within the quotes is important as it would match 5 or more letter words.
05:56	We may be specific about where in the line we want to search for our pattern.
06:01	It may be at the beginning of the line.
06:04	For that we have the caret sign.
06:07	Now if we want to get those entries whose roll numbers start with A.
06:14	We know that roll is the first field in the file.
06:19	We type at the prompt: grep within double quotes caret sign A after the quotes grepdemo.txt
06:29	Press Enter.
06:32	The output is displayed.
06:35	Similarly to match a pattern at the end of the file, we have the dollar sign.
06:41	To find stipends between 7000 to 8999 we have to write:
06:50	grep space within double quotesopening square bracket 78 closing square bracket ...dollar sign after the quotes space grepdemo.txt
07:06	Press Enter .
07:08	The output is displayed.
07:11	This brings us to the end of this tutorial.
07:13	Let us summarize.
07:16	In this tutorial we learnt:
07:18	* To match more than one pattern
07:20	* To check a word that has different spelling
07:24	* Character class
07:25	* The use of asterisk
07:28	* To match any one character using dot
07:32	* To match a pattern at the beginning of the file
07:35	* To match a pattern at the end of the file.
07:40	As an assignment, list those entries that are 5 letters long and starts with Y.
07:48	Watch the video available at the link shown below.
07:51	It summarizes the Spoken Tutorial project.
07:54	If you do not have good bandwidth, you can download and watch it.
07:59	The Spoken Tutorial Project Team conducts workshops using spoken tutorials,
08:05	gives certificates to those who pass an online test.
08:08	For more details, please write to contact@spoken-tutorial.org
08:15	Spoken Tutorial Project is a part of the Talk to a Teacher project.
08:20	It is supported by the National Mission on Education through ICT, MHRD, Government of India.
08:26	More information on this Mission is available at the link shown below : http://spoken-tutorial.org\NMEICT-Intro
08:32	The script has been contributed by Anirban and Sachin.
08:36	This is Ashwini Patil from IIT Bombay, signning off. Thank you for joining.

Contributors and Content Editors

Gaurav, Madhurig, PoojaMoolya, Sandhya.np14