Use of grep command

grep : grep command is used to search a string and regular expression from a given file.
                                      Syntax:$grep <string/pattern> filename
Ex :$grep india demo
It prints then line containing india.

Ex :$grep india demo demo1 demo2
It search india string from demp,demo1 & demo2 files and print lines having india.

Ex :$grep india *
It searches the india string from the current directory of all files.

Ex :$grep "indian politics" demo

Use of grep command with options:

a)Syntax :$grep -i "String" <filename>
Ex :$grep -i "India" demo
This command ignores case sensitive.

b)Syntax :$grep -c "String" <filename>
Ex :$grep -c "india" demo
This command counts number of lines having string india.

c)Syntax :$grep -n "String" <filename>
Ex :$grep -n "india" demo
This command counts lines with line numbers having string india.

d)Syntax :$grep -v "String" <filename>
Ex :$grep -v "india" demo
This command displays the lines do not having string india.

e)Syntax :$grep -o "String" <filename>
Ex :$grep -o "india" demo
This command prints only pattern containing india.