Redirecting Text Output to a File from a Console Application

Introduction

I decided to write this article after being unable to find any example code on how to redirect console output to a file. There were examples of writing to a memory stream but I needed to output to a file because I was worried about the potential size of the memory stream required to do what I wanted. I had much help from my friend Armand so I would like to have him credited as a major contributor.

Background

I was experiencing errors when I used the redirection within the arguments sent to the process.

My code was written to back up a MySQL database using the tool mysqldump.exe but it should be easily changed to work with other console applications.

Using the Code

The sample is quite small. I have used comments to describe the process.

StreamWriter _outputStream;

// Called asynchronously with a line of data
private void OnDataReceived(object Sender, DataReceivedEventArgs e)
{
    if ((e.Data != null)&&(_outputStream != null))
        _outputStream.WriteLine(e.Data);
}

public void BackupLocalDatabase(string DatabaseName, string UserID, string Password,
    string OutputFilename)
{
#region BackupLocalDatabase
    string fnName = "BackupLocalDatabase";
    try
    {
        _outputStream = new StreamWriter(OutputFilename);
        try
        {
            // --databases to force CREATE DATABASE
            // --hex-blob to force output of blobs as hex strings
            string _args = string.Format(
                " --databases {0} --user={1} --password={2} --hex-blob",
                DatabaseName, UserID, Password);

            // Info object
            ProcessStartInfo _info = new ProcessStartInfo("mysqldump");
            _info.Arguments = _args;
            _info.UseShellExecute = false;
            _info.RedirectStandardError = true;
            _info.RedirectStandardOutput = true;

            // Process object
            Process _process = new Process();
            _process.StartInfo = _info;

            // Set up the event handler to call back with
            // each line of output
            _process.OutputDataReceived += new DataReceivedEventHandler(OnDataReceived);
            _process.Start();
            _process.BeginOutputReadLine();
            _process.WaitForExit();

            //TODO error checks here

        }
        finally
        {
            _outputStream.Flush();
            _outputStream.Close();
        }
    }
    catch (Exception e)
    {
        LogException(fnName, e);
        throw e;
    }
#endregion
}// function

History

2008-06-16 Written