A simple grep clone that also shows line numbers.

grope.cs

using System;

namespace grope
{
	class MainClass
	{
		public static void Main (string[] args)
		{
			if (args.Length == 0) {
				Console.WriteLine ("Usage: grope searchTerm\nReceives input from stdin.");
				return;
			}

			int lineNumber = 1;
			if (args.Length == 1) {
				string line;
				while ((line = Console.ReadLine ()) != null) {
					if (line.Contains (args [0]))
						Console.WriteLine (lineNumber + " " + line.Trim ());
					lineNumber++;
				}
			}
		}
	}
}