try
{
    Console.WriteLine("———————————————————————————————————————————");
    Console.WriteLine("Program to perform the operations on a file");
    Console.WriteLine("———————————————————————————————————————————");
    FileStream f = new FileStream("/home/kodingwindow/Trial.txt", FileMode.Append);
    //"Hi There!" text is present in Trial.txt
    StreamWriter w = new StreamWriter(f);
    w.WriteLine("Welcome to Kodingwindow!");
    w.Close();
    f.Close();

    FileStream fs = new FileStream("/home/kodingwindow/Trial.txt", FileMode.Open);
    StreamReader r = new StreamReader(fs);
    string line = "";
    while ((line = r.ReadLine()) != null)
    {
        Console.WriteLine(line);
    }
    r.Close();
    fs.Close();
    Console.WriteLine("———————————————————————————————————————————");
}
catch (FileNotFoundException)
{
    Console.WriteLine("File not found");
}
catch (Exception e)
{
    Console.WriteLine(e);
}
finally
{
    Thread.Sleep(5000);
}

kodingwindow@kw:~/csharp$ dotnet run
———————————————————————————————————————————
Program to perform the operations on a file
———————————————————————————————————————————
Hi There!
Welcome to Kodingwindow!
———————————————————————————————————————————
kodingwindow@kw:~/csharp$