How do I select a .Net application configuration file from a command line parameter?

Question

I would like to override the use of the standard app.config by passing a command line parameter. How do I change the default application configuration file so that when I a

Answer 1

This is not exactly what you are wanting... to redirect the actual ConfigurationManager static object to point at a different path. But I think it is the right solution to your problem. Check out the OpenExeConfiguration method on the ConfigurationManager class.

If the above method is not what you are looking for I think it would also be worth taking a look at using the Configuration capabilities of the Enterprise Library framework (developed and maintained by the Microsoft Patterns & Practices team).

Specifically take a look at the FileConfigurationSource class.

Here is some code that highlights the use of the FileConfigurationSource from Enterprise Library, I believe this fully meets your goals. The only assembly you need from Ent Lib for this is Microsoft.Practices.EnterpriseLibrary.Common.dll.

static void Main(string[] args)
{
    //read from current app.config as default
    AppSettingsSection ass = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None).AppSettings;

    //if args[0] is a valid file path assume it's a config for this example and attempt to load
    if (args.Length > 0 && File.Exists(args[0]))
    {
        //using FileConfigurationSource from Enterprise Library
        FileConfigurationSource fcs = new FileConfigurationSource(args[0]);
        ass = (AppSettingsSection) fcs.GetSection("appSettings");
    }

    //print value from configuration
    Console.WriteLine(ass.Settings["test"].Value);
    Console.ReadLine(); //pause
}