grep (Global Regular Expression Parser) Command in Unix

• Search file(s) for specific text. 
• By default, grep displays the matching lines. 
• Search pattern allows regular expression

Syntax : $grep [options] [find pattern] [filename]

Options	Descriptions
-v	Print all lines that dont match pattern
-n	Print the matched line and its line number
-l	Print only the names of files with matching lines
-c	Print only the count of matching lines
-i	Match either upper or lowercase
-w	Print the lines which is matched exact given word
-r	Recursive search folder and sub-folder

Example:

file name : sample.dat

applas11i13

sunday is holiday

monday

tuesday

wednesday

thursday

friday

saturday

Sunday SUCCESS

SUNDAY 1234

SUUNDAY

this

$ grep "Sunday" sample.dat

Sunday SUCCESS

This is used to find the line in which the word ‘Sunday’ in a file ‘sample.dat’ occurs  . This is also case sensitive.

$ grep -i "Sunday" sample.dat

sunday is holiday

Sunday SUCCESS

SUNDAY 1234

This is used to find the line in which the word ‘Sunday’ in a file ’sample.dat’ occurs. This is ignoring the case sensitive.

$ grep -v "Sunday" sample.dat

applas11i13

sunday is holiday

monday

tuesday

wednesday

thursday

friday

saturday

SUNDAY 1234

SUUNDAY

this

This is used to find all the line except the word ‘Sunday’  in a file ‘sample.dat’. This is also case sensitive.

$ grep -iv "Sunday" sample.dat

applas11i13

monday

tuesday

wednesday

thursday

friday

saturday

SUUNDAY

this

  This is used to find all the line except the word ‘Sunday’ in a file ‘sample.dat’. This is ignoring case sensitive.

$ grep -w "is" sample.dat

sunday is holiday

           This is used to find the line in which the word ‘is’ occurs  in a file ‘sample.dat’. This is also case sensitive.

$ grep  "is" sample.dat

sunday is holiday

this 

       This is used to find the line in which  the  word ‘is’ occurs in a file ‘sample.dat’. This is also case sensitive.