File access is made simple with C# (Mono) on FreeBSD.

Reading a text file with C# (Mono)

To read a file, use a StreamReader object. However, it is easy if you don’t do a new StreamWriter("File.txt") but instead use File.OpenText("File.txt") to create the StreamReader. Once you have the stream, you just need to run the stream’s ReadToEnd() function.

Here is a snippet to read a text file as a string.

// Open the file into a StreamReader
StreamReader file = File.OpenText("SomeFile.txt");
// Read the file into a string
string s = file.ReadToEnd();

Now that you have the text file as a string, you can manipulate the string as you desire.

Writing to a text file with C# (Mono)

To write a text file, use StreamWriter.

string str = "Some text";
// Hook a write to the text file.
StreamWriter writer = new StreamWriter("SomeFile.txt");
// Rewrite the entire value of s to the file
writer.Write(str);

You can also just add a line to the end of the file as follows:

string str = "Some text";
// Hook a write to the text file.
StreamWriter writer = new StreamWriter("SomeFile.txt");
// Rewrite the entire value of s to the file
writer.WriteLine(str);

Example for learning

An example of these in a little project file made with MonoDevelop.

using System;
using System.IO;

namespace FileAccess
{
	class MainClass
	{
		public static void Main (string[] args)
		{
			string FileName="TestFile.txt";

			// Open the file into a StreamReader
			StreamReader file = File.OpenText(FileName);
			// Read the file into a string
			string s = file.ReadToEnd();
			// Close the file so it can be accessed again.
			file.Close();

			// Add a line to the text
			s  += "A new line.\n";

			// Hook a write to the text file.
			StreamWriter writer = new StreamWriter(FileName);
			// Rewrite the entire value of s to the file
			writer.Write(s);

			// Add a single line
			writer.WriteLine("Add a single line.");

			// Close the writer
			writer.Close();
		}
	}
}

Well, this should get you started.