View source for BOSS-Linux/C3/The-grep-command/English-timed

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|'''Time''' 
|'''Narration''' 

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|00:01
|Welcome to the spoken tutorial on '''grep''' command

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|00:05
|In this tutorial we will learn '''grep command'''.

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|00:09
|We will do this with the help of some examples.

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|00:12
|To record this tutorial, I am using

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|00:15
|*''' Linux''' ''' Operating System''' 

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|00:18
| and *'''GNU BASH''' version 4.2.24

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|00:22
|Please note,''' GNU bash''' version 4 or above is recommended to practise this tutorial.

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|00:30
|As prerequisites You should know basics of '''Linux terminal'''

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|00:34
|For relevant tutorials, please visit our website which is as shown.

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|00:39
|First let us know about regular expressions.

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|00:43
|*Regular expressions are pattern matching techniques.

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|00:47
|*When we have to find out whether a pattern exist in a line, paragraph or a file.

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|00:54
|For ex. If you want to search a phone number in the telephone directory 
 
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| 01:01
|  Or  To find a keyword in a paragraph or a line, we use '''grep command'''
Let us move on to '''grep'''.

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|01:08
|'''grep''' searches for one or more patterns in one or more line, paragraph or a file.

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|01:15
|If filename is not mentioned,''' grep''' search for the patterns in the standard input.

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|01:22
|If filename is missing, '''grep''' searches for the patterns in the standard input.

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|01:28
|I will demonstrate usage of '''grep''' using a demo file called '''grepdemo.txt'''

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|01:35
|Let us see the content of the file.

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|01:37
|This is a file that has 13 entries. 

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|01:41
|Each entry has 6 fields roll number, name, stream, marks, and stipend amount. 

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|01:50
|The fields are separated by a bar, which is called a '''delimiter'''.

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|01:55
|Let us see how '''grep''' works.

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|01:58
|Say we want to use '''grep command''', to see who are the students in the '''computers''' stream.

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|02:04
|For this we have to open the '''terminal'''.

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|02:07
|Now type on the '''terminal''':

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|02:09
|'''grep space (within double quotes) computers after the double quotes space  grepdemo .txt'''

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|Press Enter

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|02:20
|This would enlist those entries where stream is '''computers'''.

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|02:25
|Now compare the result with the original file. 

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|02:29
|Come back to our text editor.

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|02:31
|We see that the entry for ''' Zubin''' is not enlisted.

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|02:37
|Why this is so?

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|02:38
|This is because '''grep''' searched for the pattern '''“computers”''' with small '''c''' 

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|02:43
|While for '''Zubin''', the stream is “Computers” with a capital '''C'''.

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|02:48
|The pattern matching is '''case sensitive'''.

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|02:51
|To make it '''case''' insensitive, we need to use the '''minus i ''' option with '''grep'''.

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|02:58
|Come back to our terminal Now Type:
'''grep space (minus) i  space (within double quotes) “'''computers”''' after the '''double quotes space grepdemo.txt'''

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|03:12
|Press ''' Enter.'''

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|03:13
|This will now enlist all the four entries.

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|03:17
|So we saw, '''grep''' enlists only those lines of files that match a given pattern.

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|03:23
|We may do the reverse.

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|03:26
|It is possible to make '''grep''' enlist only those lines that '''do not''' match the pattern.

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|03:32
|For that we have the '''minus v''' option.

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|03:35
|Say, we want to enlist those entries of students who have not passed.

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|03:40
|We can also store this result in another file

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|03:43
|For this type:
'''grep space minus iv space''' Within double quotes '''pass after the double quotes space grepdemo.txt space greater than sign space notpass.txt '''

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|04:02
|Press '''Enter.'''

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|04:04
|To see the content of file, type: '''cat space notpass.txt '''

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|04:11
|Press '''Enter'''.

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|04:12
|The output is displayed.

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|04:15
|Now at the '''prompt''' type:

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|04:17
|''grep space minus i space''' within double quotes '''fail''' after the double quotes space '''grepdemo.txt'''

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|04:28
|And Press '''Enter.'''

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|04:30
|This is different.
  
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|04:32
|This will include those students who are failed but their result is incomplete.

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|04:37
|If we want to see the line number in the file at which the enlisted entries are, we have the '''minus n''' option

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|04:46
|Let us clear the '''prompt'''. 

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|04:49
|  Now type "'''grep space -in space within double quote "fail" after the double quotes space grepdemo.txt'''

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|05:01
|Press '''Enter'''.

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|05:03
|The line number is displayed.

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|05:06
|The patterns so far have been of single word.

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|05:10
|We may have multiword patterns as well. 

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|05:13
|But the entire pattern must be within '''quotes'''.

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|05:17
|So type: '''grep space minus i space'''within double quotes '''ankit space saraf after the double quotes space grepdemo.txt '''

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|05:29
|Press '''Enter'''.

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|05:31
|We see that '''Ankit Saraf''''s record is displayed.

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|05:35
|We can also find patterns in multiple files.

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|05:39
|For this Type:
'''grep space minus i space''' within double quotes '''fail after double quotes space grepdemo.txt space notpass.txt''' 

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|05:55
|'''Press Enter'''.

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|05:57
|The output is displayed.

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|05:59
|With multiple files, '''grep''' will write the name of the file in which the entry was found.'''grepdemo.txt''' and '''notpass.txt'''

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|06:10
|These are the records from '''notpass.txt''' file and these are the records from '''grepdemo.txt''' file.

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|06:18
|Suppose we may only want to know the '''number of matches '''or '''count''' .

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|06:23
|For that, we have the '''minus c''' option

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|06:27
| So Type: '''grep space minus c space'''within double quotes '''Fail  with a capital F after the quotes space grepdemo.txt'''

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|06:40
|Press '''Enter'''.

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|06:42
|This will give us the '''count''' of number of lines matched.

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|06:46
|This brings us to the end of this tutorial.

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|06:51
|Let us summarize.

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| 06:53
| In this tutorial we learnt,

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|06:55
|*To see the content of a file
**eg. '''cat filename'''
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|06:59
|*To list the entries of a particular stream
**eg. '''grep “computers” grepdemo.txt'''

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|07:06
|*To ignore cases
**eg. '''grep -i “computers” grepdemo.txt'''

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|07:14
|*Lines that do not match the pattern
**eg. '''grep -iv “pass” grepdemo.txt'''

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|07:22
|*To list the line numbers with the entries
**eg.''' grep -in “fail” grepdemo.txt'''

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|07:31
|*To store the result in another file
**eg. '''grep -iv “pass” grepdemo.txt > notpass.txt'''

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|07:41
|And*To know the count
**eg.''' grep -c “Fail” grepdemo.txt'''

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|07:48
|As an assignment,

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|07:50
|Explore some other commands like '''-E, + and ?'''

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|07:56
|Watch the video available at the link shown below.

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|07:58
|It summarises the Spoken Tutorial project.

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|08:01
|If you do not have good bandwidth, you can download and watch it.

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|08:05
|The Spoken Tutorial Project Team

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|08:07
|*Conducts workshops using spoken tutorials

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|08:11
|*Gives certificates to those who pass an online test

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|08:14
|For more details, please write to
'''contact@spoken-tutorial.org'''

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|08:21
|Spoken Tutorial Project is a part of the Talk to a Teacher project

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|08:25
|It is supported by the National Mission on Education through ICT, MHRD, Government of India

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|08:32
|More information on this Mission is available at: http://spoken-tutorial.org\NMEICT-Intro

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|08:36
|This is Ashwini Patil from IIT Bombay signning off. Thank you for joining.

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