C#:
Writing to standard error

How to:

In C#, writing to standard error can be achieved using the Console.Error stream. This stream is used specifically for error messages and diagnostics. Here’s a basic example:

Console.Error.WriteLine("Error: Failed to process the request.");

Sample output (to stderr):

Error: Failed to process the request.

For scenarios where you might be using a third-party library that offers advanced logging capabilities, like Serilog or NLog, you can configure these libraries to write error logs to stderr. While these examples focus on simple console redirection, remember that in production applications, logging frameworks offer much more robust error handling and output options. Here’s a simple example with Serilog:

First, install the Serilog package and its Console sink:

Install-Package Serilog
Install-Package Serilog.Sinks.Console

Then, configure Serilog to write to stderr:

using Serilog;

Log.Logger = new LoggerConfiguration()
    .WriteTo.Console(standardErrorFromLevel: Serilog.Events.LogEventLevel.Error)
    .CreateLogger();

Log.Information("This is a normal message.");
Log.Error("This is an error message.");

Sample output (to stderr for the error message):

[15:04:20 ERR] This is an error message.

Note: The standardErrorFromLevel configuration in Serilog’s console sink redirects all log events at the specified level (Error, in this case) or higher to the standard error stream, while lower-level messages like Information are written to the standard output stream.