grep added

shell/grep.txt

@@ -0,0 +1,67 @@
+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>