Makefile-tutorial/shell/grep.txt

Grep:
(Global regular expression print)
-----------------------------------

Purpose:
	The purpose of grep is to search for text within file.


To use grep:

	Print the content of the file using cat command and pipe it
	to grep command.

	cat <filename> | grep <string-pattern>

	Pass the string pattern as an argument to search for it in the file.

	* To search for anything except the <string-pattern>

		cat <filename> | grep -v <string-pattern>

		-v : excluding the <string-pattern> and searching everything else.

* To search using grep without using cat command.

	Use command:

		grep <string-pattern> <file-location>

	This gives same output as it will show if we use it with cat command.

* To mention the line number for each <string-pattern> searched and found in the file.

	Use command:

		grep -n <string-pattern> <file-location>

* To get only the count of the occurences of the <string-pattern> in the <file>

	Use command:

		grep -c <string-pattern> <file-location>


NOTE:

Grep is case sensitive for the <string-pattern> we use for searching.


* To Ignore the case sensitivity.

	Use command:

		grep -i <string-pattern> <file-location>

* To look through every file in the given directory where grep is executed.

	Use command:
		
		grep  <string-pattern> * 

* To know where the particular pattern are present without knowing the particular file
  and directory.

	Use command:
		
		grep -r <string-pattern> <path>