Linux/C3/More-on-grep-command/English
Title of script: More on grep command
Author : Sachin Patil
Keywords:Search,Pattern,regular expressions,extended regular expression
Visual Cue | Narration |
Display Slide 1
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Welcome to the spoken tutorial on more on grep command |
Display Slide 2 | In this tutorial we will learn some more grep commands.
Through some examples |
Display Slide 3 | To record this tutorial, I am using
Ubuntu Linux 12.04 Operating System and GNU BASH version 4.2.24 Please note, GNU bash version 4 or above is recommended to practice this tutorial. |
Display Slide 4 | As prerequisites
You should know Basics of linux terminal. You should be aware of grep. For relevant tutorials please visit our website: |
At the prompt type
“grep -e “electronics” -e “civil” grepdemo.txt” [enter] |
We can match more than one patterns as well.
Then we have to use the -e option. I will use the same example grepdemo.txt Say we want to find information for those who are either in civil or electronics.
grep space hyphen e space in double quotes electronics space hyphen e space in double quotes civil space grepdemo.txt Press Enter. The output is displayed. |
At the prompt type
“grep -ie “choudhury” -ie “chowdhari” grepdemo.txt” [enter] |
Say you need to look into people whose title is choudhury.
So what is the solution?.
Press Enter. The output is displayed. But there can be many other ways in which we can write the name.
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Display Slide 5 | A regular expression provides a concise and flexible means for matching strings of text.
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There are a number of regular expression characters.
Let us see them one by one. | |
Display Slide 6 | The character class.
It allows us to specify a group of characters within a pair of square brackets .
Eg. [abc] would mean that this regular expression matches either a or b or c. |
At the prompt
grep -i “ch[ao][uw]dh[ua]r[yi]” grepdemo.txt [enter] |
To match choudhury we may type at the prompt
The output is displayed. It still does not match choudhuree with double e. |
Display Slide 7 | If we want to specify a large range then write:
first letter dash last letter of the range
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Display Slide 8
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The * refers to 0 or more occurrences of the immediately preceding character.
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At the prompt
grep -i “m[ei]*raa*” grepdemo.txt
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So to match the students name whose name is Mira
We write at the prompt:
The output is displayed. |
The dot “.”
This regular expression matches any one character. | |
At the prompt
grep “M...” grepdemo.txt
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Say we want to search any words that are 4 letters long and start with M.
Press Enter. The output is displayed.
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Display Slide 10 | We may be specific about where in the line we want to search for our pattern.
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At the prompt
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Now if we want those entries whose roll numbers start with A.
We know that roll is the first field in the file. We write at the prompt:
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Display Slide 11
grep “[78]...$ ” grepdemo.txt
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Similarly to match a pattern at the end of the file, we have the dollar sign.
grep space in double quotes [78]...dolar sign space grepdemo.txt Press Enter The output is displayed. This brings me to the end of this tutorial. Let us summarize. |
Display Slide 12
Summary |
In this tutorial we learnt,
eg. grep -e “electronics” -e “civil” grepdemo.txt
eg. grep -ie “choudhury” -ie “chowdhari” grepdemo.txt
eg. grep -i “ch[ao][uw]dh[ua]r[yi]” grepdemo.txt
eg. grep -i “m[ei]*raa*” grepdemo.txt
eg. grep “M...” grepdemo.txt
eg. grep “^A” grepdemo.txt
eg. grep “[78]...$ ” grepdemo.txt
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Display Slide 13 | As an assignment,
List those entries that are 5 letters long and starts with Y. |
Display Slide 14
Acknowledgement Slide |
Watch the video available at the link shown below
It summarises the Spoken Tutorial project If you do not have good bandwidth, you can download and watch it |
Display Slide 15
Spoken Tutorial Workshops |
The Spoken Tutorial Project Team
Conducts workshops using spoken tutorials Gives certificates to those who pass an online test For more details, please write to contact@spoken-tutorial.org |
Display Slide 16
Acknowledgement |
Spoken Tutorial Project is a part of the Talk to a Teacher project
It is supported by the National Mission on Education through ICT, MHRD, Government of India More information on this Mission is available at: http://spoken-tutorial.org\NMEICT-Intro |
No Last Slide for tutorials created at IITB
Display the previous slide only and narrate this line. |
The script has been contributed by Sachin Patil.
This is Ashwini Patil from IIT Bombay signning off. Thank you for joining. |