add: new input scanning exercises

23-input-scanning/exercises/04-grep/main.go

@@ -0,0 +1,29 @@
+package main
+
+// ---------------------------------------------------------
+// EXERCISE: Grep Clone
+//
+//  Create a grep clone. grep is a command-line utility for
+//  searching plain-text data for lines that match a specific
+//  pattern.
+//
+//  1. Feed the shakespeare.txt to your program.
+//
+//  2. Accept a command-line argument for the pattern
+//
+//  3. Only print the lines that contains that pattern
+//
+//  4. If no pattern is provided, print all the lines
+//
+//
+// EXPECTED OUTPUT
+//
+//  go run main.go come < shakespeare.txt
+//
+//    come night come romeo come thou day in night
+//    come gentle night come loving black-browed night
+//
+// ---------------------------------------------------------
+
+func main() {
+}