cse15l-lab-reports

Lab Report 3 - Researching Commands

Yangyang Liu
CSE 15L Section B02
PID: A17360266

Researching Commands

I have chosen do research on the grep command.

I will be using the files and directories in ./technical to show my examples. It is found here.

   

1. -i (Case-insensitive Search)

This grep command option allows you to make a search for a pattern, regardless of the letter case.

 

Example 1:

$ grep -i "CrEaTiVe" ./technical/911report/*.txt
./technical/911report/chapter-3.txt: creative as possible in their thinking" about preventing a Bin Ladin attack on U.S.

This command searches for the text “CrEaTiVe” in all .txt files in ./technical/911report/,ignoring the case of each letter.
It is useful when searching for words that have inconsistent capitalization.

 

Example 2:

$ grep -i "ERROR" ./technical/plos/journal.pbio.0020047.txt
      painful is the fact that this book is filled with factual errors, glib and misleading
      accurately later in the book, but that is a weak excuse for this early error.

This command searches for the text “ERROR” in ./technical/plos/journal.pbio.0020047.txt, ignoring the case of each letter.
Again, it’s useful if you want to found a keyword that may be capitalized differently throughout the files.    

Source used: https://www.geeksforgeeks.org/grep-command-in-unixlinux/

 

2. -c (Display Match Count)

This grep command option allows you to search for the number of lines that matches the pattern.

 

Example 1:

$ grep -c "file" ./technical/911report/*.txt
./technical/911report/chapter-1.txt:1
./technical/911report/chapter-10.txt:1
./technical/911report/chapter-11.txt:0
./technical/911report/chapter-12.txt:2
./technical/911report/chapter-13.1.txt:0
./technical/911report/chapter-13.2.txt:50
./technical/911report/chapter-13.3.txt:12
./technical/911report/chapter-13.4.txt:15
./technical/911report/chapter-13.5.txt:15
./technical/911report/chapter-2.txt:0
./technical/911report/chapter-3.txt:4
./technical/911report/chapter-5.txt:1
./technical/911report/chapter-6.txt:1
./technical/911report/chapter-7.txt:1
./technical/911report/chapter-8.txt:2
./technical/911report/chapter-9.txt:1
./technical/911report/preface.txt:0

This command displays the number of lines in each .txt file in the ./technical/911report/ that contains the pattern “file”.
This is useful if you want to get a quick overview of how many matches are found.

 

Example 2:

$ grep -c "report" ./technical/biomed/rr74.txt
14

This command displays the number of lines in rr74.txt located in the ./technical/biomed/ directory. Again, this is useful if you want to know how many lines in a file contain the word you are looking for.    

Source used: https://www.geeksforgeeks.org/grep-command-in-unixlinux/

 

3. -C[num] (Before and After Lines)

This grep command option prints the searched line and num before and after the result.

 

Example 1:

$ grep -C1 "expression" ./technical/biomed/rr74.txt
        following sever hypoxia has been reported in rats [ 4, 13,
        14, 15, 16]. Less is certain about the expression of NOS in
        the murine lung following hypoxia, with previous reports [
-- 
        determined using 18 S rRNA primers/probes (Applied
        Biosystems) and eNOS, iNOS and nNOS expression determined
        using the primer/probe sequences shown in Table 1.
--
...

This command displays all the lines in the file rr74.txt located in the ./technical/biomed/ directory along with the line before and after the matching lines. This is useful to for getting context of any particular matched line.

 

Example 2:

* grep -C2 "creative" ./technical/911report/*.txt
./technical/911report/chapter-3.txt-    dedicated to trying "to evaluate the threat of a terrorist attack in the United
./technical/911report/chapter-3.txt-    States by the Usama bin Ladin network."107The CSG members were "urged to be as
./technical/911report/chapter-3.txt:    creative as possible in their thinking" about preventing a Bin Ladin attack on U.S.
./technical/911report/chapter-3.txt-    territory. Participants noted that while the FBI had been given additional resources
./technical/911report/chapter-3.txt-    for such efforts, both it and the CIA were having problems exploting leads by

This command displays all the lines in the .txt files located in the ./technical/911report/ directory along with two lines before and after the matching lines. In this case, only one line in the .txt files located in ./technical/911report/ contains the pattern “creative”. Again, this is useful to get the context of a matched line.    

Source used: https://www.geeksforgeeks.org/grep-command-in-unixlinux/

 

4. -v (Inverting Pattern Match)

This grep option displays the lines that do not contain the specified pattern.

 

Example 1:

$ grep -v "a" ./technical/government/Media/Wingates_winds.txt




BY BRAD BENNETT
is strong enough.
funded by Sept. 30, 2003.
million.




// The empty lines are actually lines in the .txt file

This command displays the lines in the file Wingates_winds.txt located in `./technical/government/Media” that do not contain the letter “a”. This is possibly useful when you want to find lines where you don’t want a certain word.

 

Example 2:

$ grep -v "a" ./technical/biomed/rr74.txt




        Introduction
        immunohistochemistry.
        
        
        
            Mice
            
            
            Exposure environments
        ...

This command finds all the lines in the file rr74.txt lcoated in ./technical/biomed/ that do not contain the letter “a”. Again, this is possibly useful when you want to find lines where you don’t want a certain word or character.    

Source used: https://www.geeksforgeeks.org/grep-command-in-unixlinux/

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